Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
Wed, Apr 04, 2018 at 03:04:26AM CEST, dsah...@gmail.com wrote: >On 4/3/18 9:42 AM, Jiri Pirko wrote: >>> >>> There are other use cases that want to hide a device from userspace. I >> >> What usecases do you have in mind? > >As mentioned in a previous response some kernel drivers create control >netdevs. Just as in this case users should not be mucking with it, and virtio_net. Any other drivers? >S/W like lldpd should ignore it. It's just a matter of identification of the netdevs, so the user knows what to do. > >> >>> would prefer a better solution than playing games with name prefixes and >>> one that includes an API for users to list all devices -- even ones >>> hidden by default. >> >> Netdevice hiding feels a bit scarry for me. This smells like a workaround >> for userspace issues. Why can't the netdevice be visible always and >> userspace would know what is it and what should it do with it? >> >> Once we start with hiding, there are other things related to that which >> appear. Like who can see what, levels of visibility etc... >> > >I would not advocate for any API that does not allow users to have full >introspection. The intent is to hide the netdev by default but have an >option to see it. As an administrator, I want to see all by default. I think it is reasonable requirements. Again, this awfully smells like a workaround... ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v30 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT
On 04/04/2018 02:47 AM, Michael S. Tsirkin wrote:
On Wed, Apr 04, 2018 at 12:10:03AM +0800, Wei Wang wrote:
+static int add_one_sg(struct virtqueue *vq, unsigned long pfn, uint32_t len)
+{
+ struct scatterlist sg;
+ unsigned int unused;
+
+ sg_init_table(&sg, 1);
+ sg_set_page(&sg, pfn_to_page(pfn), len, 0);
+
+ /* Detach all the used buffers from the vq */
+ while (virtqueue_get_buf(vq, &unused))
+ ;
+
+ /*
+* Since this is an optimization feature, losing a couple of free
+* pages to report isn't important. We simply return without adding
+* the page hint if the vq is full.
why not stop scanning of following pages though?
Because continuing to send hints is a way to deliver the maximum
possible hints to host. For example, host may have a delay in taking
hints at some point, and then it resumes to take hints soon. If the
driver does not stop when the vq is full, it will be able to put more
hints to the vq once the vq has available entries to add.
+* We are adding one entry each time, which essentially results in no
+* memory allocation, so the GFP_KERNEL flag below can be ignored.
+* Host works by polling the free page vq for hints after sending the
+* starting cmd id, so the driver doesn't need to kick after filling
+* the vq.
+* Lastly, there is always one entry reserved for the cmd id to use.
+*/
+ if (vq->num_free > 1)
+ return virtqueue_add_inbuf(vq, &sg, 1, vq, GFP_KERNEL);
+
+ return 0;
+}
+
+static int virtio_balloon_send_free_pages(void *opaque, unsigned long pfn,
+ unsigned long nr_pages)
+{
+ struct virtio_balloon *vb = (struct virtio_balloon *)opaque;
+ uint32_t len = nr_pages << PAGE_SHIFT;
+
+ /*
+* If a stop id or a new cmd id was just received from host, stop
+* the reporting, and return 1 to indicate an active stop.
+*/
+ if (virtio32_to_cpu(vb->vdev, vb->cmd_id_use) != vb->cmd_id_received)
+ return 1;
+
this access to cmd_id_use and cmd_id_received without locks
bothers me. Pls document why it's safe.
OK. Probably we could add below to the above comments:
cmd_id_use and cmd_id_received don't need to be accessed under locks
because the reporting does not have to stop immediately before
cmd_id_received is changed (i.e. when host requests to stop). That is,
reporting more hints after host requests to stop isn't an issue for this
optimization feature, because host will simply drop the stale hints next
time when it needs a new reporting.
+ return add_one_sg(vb->free_page_vq, pfn, len);
+}
+
+static int send_start_cmd_id(struct virtio_balloon *vb, uint32_t cmd_id)
+{
+ struct scatterlist sg;
+ struct virtqueue *vq = vb->free_page_vq;
+
+ vb->cmd_id_use = cpu_to_virtio32(vb->vdev, cmd_id);
+ sg_init_one(&sg, &vb->cmd_id_use, sizeof(vb->cmd_id_use));
+ return virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
+}
+
+static int send_stop_cmd_id(struct virtio_balloon *vb)
+{
+ struct scatterlist sg;
+ struct virtqueue *vq = vb->free_page_vq;
+
+ sg_init_one(&sg, &vb->stop_cmd_id, sizeof(vb->cmd_id_use));
why the inconsistency?
Thanks, will make it consistent.
Best,
Wei
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
On Tue, Apr 3, 2018 at 8:42 AM, Jiri Pirko wrote: > Sun, Apr 01, 2018 at 06:11:29PM CEST, dsah...@gmail.com wrote: >>On 4/1/18 3:13 AM, Si-Wei Liu wrote: >>> Hidden netdevice is not visible to userspace such that >>> typical network utilites e.g. ip, ifconfig and et al, >>> cannot sense its existence or configure it. Internally >>> hidden netdev may associate with an upper level netdev >>> that userspace has access to. Although userspace cannot >>> manipulate the lower netdev directly, user may control >>> or configure the underlying hidden device through the >>> upper-level netdev. For identification purpose, the >>> kobject for hidden netdev still presents in the sysfs >>> hierarchy, however, no uevent message will be generated >>> when the sysfs entry is created, modified or destroyed. >>> >>> For that end, a separate namescope needs to be carved >>> out for IFF_HIDDEN netdevs. As of now netdev name that >>> starts with colon i.e. ':' is invalid in userspace, >>> since socket ioctls such as SIOCGIFCONF use ':' as the >>> separator for ifname. The absence of namescope started >>> with ':' can rightly be used as the namescope for >>> the kernel-only IFF_HIDDEN netdevs. >>> >>> Signed-off-by: Si-Wei Liu >>> --- >>> include/linux/netdevice.h | 12 ++ >>> include/net/net_namespace.h | 2 + >>> net/core/dev.c | 281 >>> ++-- >>> net/core/net_namespace.c| 1 + >>> 4 files changed, 263 insertions(+), 33 deletions(-) >>> >> >>There are other use cases that want to hide a device from userspace. I > > What usecases do you have in mind? Hope you're not staring at me and shouting. :) I think we had discussed a lot, and if the common goal is to merge two drivers rather than diverge, there's no better way than to hide the lower devices from all existing userspace management utiliies (NetworManager, cloud-init). This does not mean loss of visibility as we can add new API or CLI later on to get those missing ones exposed as needed, in a way existing userspace apps don't break while new apps aware of the feature know where to get it. This requirement is critical to cloud providers, which I wouldn't repeat enough why it drove me crazy if not seeing this resolved. Thanks, -Siwei > >>would prefer a better solution than playing games with name prefixes and >>one that includes an API for users to list all devices -- even ones >>hidden by default. > > Netdevice hiding feels a bit scarry for me. This smells like a workaround > for userspace issues. Why can't the netdevice be visible always and > userspace would know what is it and what should it do with it? > > Once we start with hiding, there are other things related to that which > appear. Like who can see what, levels of visibility etc... > > >> >>https://github.com/dsahern/linux/commit/48a80a00eac284e58bae04af10a5a932dd7aee00 >> >>https://github.com/dsahern/iproute2/commit/7563f5b26f5539960e99066e34a995d22ea908ed >> >>Also, why are you suggesting that the device should still be visible via >>/sysfs? That leads to inconsistent views of networking state - /sys >>shows a device but a link dump does not. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v30 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT
On Wed, Apr 04, 2018 at 12:10:03AM +0800, Wei Wang wrote:
> Negotiation of the VIRTIO_BALLOON_F_FREE_PAGE_HINT feature indicates the
> support of reporting hints of guest free pages to host via virtio-balloon.
>
> Host requests the guest to report free page hints by sending a new cmd
> id to the guest via the free_page_report_cmd_id configuration register.
>
> When the guest starts to report, the first element added to the free page
> vq is the cmd id given by host. When the guest finishes the reporting
> of all the free pages, VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID is added
> to the vq to tell host that the reporting is done. Host polls the free
> page vq after sending the starting cmd id, so the guest doesn't need to
> kick after filling an element to the vq.
>
> Host may also requests the guest to stop the reporting in advance by
> sending the stop cmd id to the guest via the configuration register.
>
> Signed-off-by: Wei Wang
> Signed-off-by: Liang Li
> Cc: Michael S. Tsirkin
> Cc: Michal Hocko
> ---
> drivers/virtio/virtio_balloon.c | 257
> +++-
> include/uapi/linux/virtio_balloon.h | 4 +
> 2 files changed, 225 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index dfe5684..18d24a4 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -51,9 +51,22 @@
> static struct vfsmount *balloon_mnt;
> #endif
>
> +enum virtio_balloon_vq {
> + VIRTIO_BALLOON_VQ_INFLATE,
> + VIRTIO_BALLOON_VQ_DEFLATE,
> + VIRTIO_BALLOON_VQ_STATS,
> + VIRTIO_BALLOON_VQ_FREE_PAGE,
> + VIRTIO_BALLOON_VQ_MAX
> +};
> +
> struct virtio_balloon {
> struct virtio_device *vdev;
> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
> +
> + /* Balloon's own wq for cpu-intensive work items */
> + struct workqueue_struct *balloon_wq;
> + /* The free page reporting work item submitted to the balloon wq */
> + struct work_struct report_free_page_work;
>
> /* The balloon servicing is delegated to a freezable workqueue. */
> struct work_struct update_balloon_stats_work;
> @@ -63,6 +76,13 @@ struct virtio_balloon {
> spinlock_t stop_update_lock;
> bool stop_update;
>
> + /* The new cmd id received from host */
> + uint32_t cmd_id_received;
> + /* The cmd id that is in use */
> + __virtio32 cmd_id_use;
> + /* Buffer to store the stop sign */
> + __virtio32 stop_cmd_id;
> +
> /* Waiting for host to ack the pages we released. */
> wait_queue_head_t acked;
>
> @@ -320,17 +340,6 @@ static void stats_handle_request(struct virtio_balloon
> *vb)
> virtqueue_kick(vq);
> }
>
> -static void virtballoon_changed(struct virtio_device *vdev)
> -{
> - struct virtio_balloon *vb = vdev->priv;
> - unsigned long flags;
> -
> - spin_lock_irqsave(&vb->stop_update_lock, flags);
> - if (!vb->stop_update)
> - queue_work(system_freezable_wq, &vb->update_balloon_size_work);
> - spin_unlock_irqrestore(&vb->stop_update_lock, flags);
> -}
> -
> static inline s64 towards_target(struct virtio_balloon *vb)
> {
> s64 target;
> @@ -347,6 +356,34 @@ static inline s64 towards_target(struct virtio_balloon
> *vb)
> return target - vb->num_pages;
> }
>
> +static void virtballoon_changed(struct virtio_device *vdev)
> +{
> + struct virtio_balloon *vb = vdev->priv;
> + unsigned long flags;
> + s64 diff = towards_target(vb);
> +
> + if (diff) {
> + spin_lock_irqsave(&vb->stop_update_lock, flags);
> + if (!vb->stop_update)
> + queue_work(system_freezable_wq,
> +&vb->update_balloon_size_work);
> + spin_unlock_irqrestore(&vb->stop_update_lock, flags);
> + }
> +
> + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
> + virtio_cread(vdev, struct virtio_balloon_config,
> + free_page_report_cmd_id, &vb->cmd_id_received);
> + if (vb->cmd_id_received !=
> + VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID) {
> + spin_lock_irqsave(&vb->stop_update_lock, flags);
> + if (!vb->stop_update)
> + queue_work(vb->balloon_wq,
> +&vb->report_free_page_work);
> + spin_unlock_irqrestore(&vb->stop_update_lock, flags);
> + }
> + }
> +}
> +
> static void update_balloon_size(struct virtio_balloon *vb)
> {
> u32 actual = vb->num_pages;
> @@ -421,42 +458,163 @@ static void update_balloon_size_func(struct
> work_struct *work)
>
> static int init_vqs(struct virtio_balloon *vb)
> {
> - struct virtqueue *vqs[3];
> - vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, sta
Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
On Sun, 1 Apr 2018 05:13:09 -0400 Si-Wei Liu wrote: > Hidden netdevice is not visible to userspace such that > typical network utilites e.g. ip, ifconfig and et al, > cannot sense its existence or configure it. Internally > hidden netdev may associate with an upper level netdev > that userspace has access to. Although userspace cannot > manipulate the lower netdev directly, user may control > or configure the underlying hidden device through the > upper-level netdev. For identification purpose, the > kobject for hidden netdev still presents in the sysfs > hierarchy, however, no uevent message will be generated > when the sysfs entry is created, modified or destroyed. > > For that end, a separate namescope needs to be carved > out for IFF_HIDDEN netdevs. As of now netdev name that > starts with colon i.e. ':' is invalid in userspace, > since socket ioctls such as SIOCGIFCONF use ':' as the > separator for ifname. The absence of namescope started > with ':' can rightly be used as the namescope for > the kernel-only IFF_HIDDEN netdevs. > > Signed-off-by: Si-Wei Liu > --- I understand the use case. I proposed using . as a prefix before but that ran into resistance. Using colon seems worse. Rather than playing with names and all the issues that can cause, why not make it an attribute flag of the device in netlink. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
Sun, Apr 01, 2018 at 06:11:29PM CEST, dsah...@gmail.com wrote: >On 4/1/18 3:13 AM, Si-Wei Liu wrote: >> Hidden netdevice is not visible to userspace such that >> typical network utilites e.g. ip, ifconfig and et al, >> cannot sense its existence or configure it. Internally >> hidden netdev may associate with an upper level netdev >> that userspace has access to. Although userspace cannot >> manipulate the lower netdev directly, user may control >> or configure the underlying hidden device through the >> upper-level netdev. For identification purpose, the >> kobject for hidden netdev still presents in the sysfs >> hierarchy, however, no uevent message will be generated >> when the sysfs entry is created, modified or destroyed. >> >> For that end, a separate namescope needs to be carved >> out for IFF_HIDDEN netdevs. As of now netdev name that >> starts with colon i.e. ':' is invalid in userspace, >> since socket ioctls such as SIOCGIFCONF use ':' as the >> separator for ifname. The absence of namescope started >> with ':' can rightly be used as the namescope for >> the kernel-only IFF_HIDDEN netdevs. >> >> Signed-off-by: Si-Wei Liu >> --- >> include/linux/netdevice.h | 12 ++ >> include/net/net_namespace.h | 2 + >> net/core/dev.c | 281 >> ++-- >> net/core/net_namespace.c| 1 + >> 4 files changed, 263 insertions(+), 33 deletions(-) >> > >There are other use cases that want to hide a device from userspace. I What usecases do you have in mind? >would prefer a better solution than playing games with name prefixes and >one that includes an API for users to list all devices -- even ones >hidden by default. Netdevice hiding feels a bit scarry for me. This smells like a workaround for userspace issues. Why can't the netdevice be visible always and userspace would know what is it and what should it do with it? Once we start with hiding, there are other things related to that which appear. Like who can see what, levels of visibility etc... > >https://github.com/dsahern/linux/commit/48a80a00eac284e58bae04af10a5a932dd7aee00 > >https://github.com/dsahern/iproute2/commit/7563f5b26f5539960e99066e34a995d22ea908ed > >Also, why are you suggesting that the device should still be visible via >/sysfs? That leads to inconsistent views of networking state - /sys >shows a device but a link dump does not. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH] vhost-net: add limitation of sent packets for tx polling
On Tue, Apr 03, 2018 at 12:29:47PM +, haibinzhang(张海斌) wrote: > > >On Tue, Apr 03, 2018 at 08:08:26AM +, haibinzhang wrote: > >> handle_tx will delay rx for a long time when tx busy polling udp packets > >> with small length(e.g. 1byte udp payload), because setting VHOST_NET_WEIGHT > >> takes into account only sent-bytes but no single packet length. > >> > >> Tests were done between two Virtual Machines using netperf(UDP_STREAM, > >> len=1), > >> then another machine pinged the client. Result shows as follow: > >> > >> Packet# Ping-Latency(ms) > >> min avg max > >> Origin 3.319 18.489 57.503 > >> 64 1.643 2.021 2.552 > >> 128 1.825 2.600 3.224 > >> 256 1.997 2.710 4.295 > >> 512*1.860 3.171 4.631 > >> 10242.002 4.173 9.056 > >> 20482.257 5.650 9.688 > >> 40962.093 8.508 15.943 > >> > >> 512 is selected, which is multi-VRING_SIZE > > > >There's no guarantee vring size is 256. > > > >Could you pls try with a different tx ring size? > > > >I suspect we want: > > > >#define VHOST_NET_PKT_WEIGHT(vq) ((vq)->num * 2) > > > > > >> and close to VHOST_NET_WEIGHT/MTU. > > > >Puzzled by this part. Does tweaking MTU change anything? > > The MTU of ethernet is 1500, so VHOST_NET_WEIGHT/MTU equals 0x8/1500=350. We should include the 12 byte header so it's a bit lower. > Then sent-bytes cannot reach VHOST_NET_WEIGHT in one handle_tx even with > 1500-bytes > frame if packet# is less than 350. So packet# must be bigger than 350. > 512 meets this condition What you seem to say is this: imagine MTU sized buffers. With these we stop after 350 packets. Thus adding another limit > 350 will not slow us down. Fair enough but won't apply with smaller packet sizes, will it? I still think a simpler argument carries more weight: ring size is a hint from device about a burst size it can tolerate. Based on benchmarks, we tweak the limit to 2 * vq size as that seems to perform a bit better, and is still safer than no limit on # of packets as is done now. but this needs testing with another ring size. Could you try that please? > and is also DEFAULT VRING_SIZE aligned. Neither Linux nor virtio have a default vring size. It's a historical construct that exists in qemu for qemu compatibility reasons. > > > >> To evaluate this change, another tests were done using netperf(RR, TX) > >> between > >> two machines with Intel(R) Xeon(R) Gold 6133 CPU @ 2.50GHz. Result as > >> follow > >> does not show obvious changes: > >> > >> TCP_RR > >> > >> size/sessions/+thu%/+normalize% > >>1/ 1/ -7%/-2% > >>1/ 4/ +1%/ 0% > >>1/ 8/ +1%/-2% > >> 64/ 1/ -6%/ 0% > >> 64/ 4/ 0%/+2% > >> 64/ 8/ 0%/ 0% > >> 256/ 1/ -3%/-4% > >> 256/ 4/ +3%/+4% > >> 256/ 8/ +2%/ 0% > >> > >> UDP_RR > >> > >> size/sessions/+thu%/+normalize% > >>1/ 1/ -5%/+1% > >>1/ 4/ +4%/+1% > >>1/ 8/ -1%/-1% > >> 64/ 1/ -2%/-3% > >> 64/ 4/ -5%/-1% > >> 64/ 8/ 0%/-1% > >> 256/ 1/ +7%/+1% > >> 256/ 4/ +1%/+1% > >> 256/ 8/ +2%/+2% > >> > >> TCP_STREAM > >> > >> size/sessions/+thu%/+normalize% > >> 64/ 1/ 0%/-3% > >> 64/ 4/ +3%/-1% > >> 64/ 8/ +9%/-4% > >> 256/ 1/ +1%/-4% > >> 256/ 4/ -1%/-1% > >> 256/ 8/ +7%/+5% > >> 512/ 1/ +1%/ 0% > >> 512/ 4/ +1%/-1% > >> 512/ 8/ +7%/-5% > >> 1024/ 1/ 0%/-1% > >> 1024/ 4/ +3%/ 0% > >> 1024/ 8/ +8%/+5% > >> 2048/ 1/ +2%/+2% > >> 2048/ 4/ +1%/ 0% > >> 2048/ 8/ -2%/ 0% > >> 4096/ 1/ -2%/ 0% > >> 4096/ 4/ +2%/ 0% > >> 4096/ 8/ +9%/-2% > >> > >> Signed-off-by: Haibin Zhang > >> Signed-off-by: Yunfang Tai > >> Signed-off-by: Lidong Chen > >> --- > >> drivers/vhost/net.c | 8 +++- > >> 1 file changed, 7 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > >> index 8139bc70ad7d..13a23f3f3ea4 100644 > >> --- a/drivers/vhost/net.c > >> +++ b/drivers/vhost/net.c > >> @@ -44,6 +44,10 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero > >> Copy TX;" > >> * Using this limit prevents one virtqueue from starving others. */ > >> #define VHOST_NET_WEIGHT 0x8 > >> > >> +/* Max number of packets transferred before requeueing the job. > >> + * Using this limit prevents one virtqueue from starving rx. */ > >> +#define VHOST_NET_PKT_WEIGHT 512 > >> + > >> /* MAX number of TX used buffers for outstanding
Re: [RFC PATCH 1/3] qemu: virtio-bypass should explicitly bind to a passthrough device
On Sun, Apr 01, 2018 at 05:13:08AM -0400, Si-Wei Liu wrote:
> @@ -896,6 +898,68 @@ void qmp_device_del(const char *id, Error **errp)
> }
> }
>
> +int pci_get_busdevfn_by_id(const char *id, uint16_t *busnr,
> + uint16_t *devfn, Error **errp)
> +{
> +uint16_t busnum = 0, slot = 0, func = 0;
> +const char *pc, *pd, *pe;
> +Error *local_err = NULL;
> +ObjectClass *class;
> +char value[1024];
> +BusState *bus;
> +uint64_t u64;
> +
> +if (!(pc = strchr(id, ':'))) {
> +error_setg(errp, "Invalid id: backup=%s, "
> + "correct format should be backup="
> + "':[.]'", id);
> +return -1;
> +}
> +get_opt_name(value, sizeof(value), id, ':');
> +if (pc != id + 1) {
> +bus = qbus_find(value, errp);
> +if (!bus)
> +return -1;
> +
> +class = object_get_class(OBJECT(bus));
> +if (class != object_class_by_name(TYPE_PCI_BUS) &&
> +class != object_class_by_name(TYPE_PCIE_BUS)) {
> +error_setg(errp, "%s is not a device on pci bus", id);
> +return -1;
> +}
> +busnum = (uint16_t)pci_bus_num(PCI_BUS(bus));
> +}
pci_bus_num is almost always a bug if not done within
a context of a PCI host, bridge, etc.
In particular this will not DTRT if run before guest assigns bus
numbers.
> +
> +if (!devfn)
> +goto out;
> +
> +pd = strchr(pc, '.');
> +pe = get_opt_name(value, sizeof(value), pc + 1, '.');
> +if (pe != pc + 1) {
> +parse_option_number("slot", value, &u64, &local_err);
> +if (local_err) {
> +error_propagate(errp, local_err);
> +return -1;
> +}
> +slot = (uint16_t)u64;
> +}
> +if (pd && *(pd + 1) != '\0') {
> +parse_option_number("function", pd, &u64, &local_err);
> +if (local_err) {
> +error_propagate(errp, local_err);
> +return -1;
> +}
> +func = (uint16_t)u64;
> +}
> +
> +out:
> +if (busnr)
> +*busnr = busnum;
> +if (devfn)
> +*devfn = ((slot & 0x1F) << 3) | (func & 0x7);
> +return 0;
> +}
> +
> BlockBackend *blk_by_qdev_id(const char *id, Error **errp)
> {
> DeviceState *dev;
> --
> 1.8.3.1
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [RFC PATCH 3/3] virtio_net: make lower netdevs for virtio_bypass hidden
On Sun, Apr 01, 2018 at 05:13:10AM -0400, Si-Wei Liu wrote:
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index aa40664..0827b7e 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -80,6 +80,8 @@ struct virtio_net_config {
> __u16 max_virtqueue_pairs;
> /* Default maximum transmit unit advice */
> __u16 mtu;
> + /* Device at bus:slot.function backed up by virtio_net */
> + __u16 bsf2backup;
> } __attribute__((packed));
I'm not sure this is a good interface. This isn't unique even on some
PCI systems, not to speak of non-PCI ones.
> /*
> --
> 1.8.3.1
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH] vhost-net: add limitation of sent packets for tx polling
On Tue, Apr 03, 2018 at 08:08:26AM +, haibinzhang(张海斌) wrote:
> handle_tx will delay rx for a long time when tx busy polling udp packets
> with small length(e.g. 1byte udp payload), because setting VHOST_NET_WEIGHT
> takes into account only sent-bytes but no single packet length.
>
> Tests were done between two Virtual Machines using netperf(UDP_STREAM, len=1),
> then another machine pinged the client. Result shows as follow:
>
> Packet# Ping-Latency(ms)
> min avg max
> Origin 3.319 18.489 57.503
> 64 1.643 2.021 2.552
> 128 1.825 2.600 3.224
> 256 1.997 2.710 4.295
> 512*1.860 3.171 4.631
> 10242.002 4.173 9.056
> 20482.257 5.650 9.688
> 40962.093 8.508 15.943
>
> 512 is selected, which is multi-VRING_SIZE
There's no guarantee vring size is 256.
Could you pls try with a different tx ring size?
I suspect we want:
#define VHOST_NET_PKT_WEIGHT(vq) ((vq)->num * 2)
> and close to VHOST_NET_WEIGHT/MTU.
Puzzled by this part. Does tweaking MTU change anything?
> To evaluate this change, another tests were done using netperf(RR, TX) between
> two machines with Intel(R) Xeon(R) Gold 6133 CPU @ 2.50GHz. Result as follow
> does not show obvious changes:
>
> TCP_RR
>
> size/sessions/+thu%/+normalize%
>1/ 1/ -7%/-2%
>1/ 4/ +1%/ 0%
>1/ 8/ +1%/-2%
> 64/ 1/ -6%/ 0%
> 64/ 4/ 0%/+2%
> 64/ 8/ 0%/ 0%
> 256/ 1/ -3%/-4%
> 256/ 4/ +3%/+4%
> 256/ 8/ +2%/ 0%
>
> UDP_RR
>
> size/sessions/+thu%/+normalize%
>1/ 1/ -5%/+1%
>1/ 4/ +4%/+1%
>1/ 8/ -1%/-1%
> 64/ 1/ -2%/-3%
> 64/ 4/ -5%/-1%
> 64/ 8/ 0%/-1%
> 256/ 1/ +7%/+1%
> 256/ 4/ +1%/+1%
> 256/ 8/ +2%/+2%
>
> TCP_STREAM
>
> size/sessions/+thu%/+normalize%
> 64/ 1/ 0%/-3%
> 64/ 4/ +3%/-1%
> 64/ 8/ +9%/-4%
> 256/ 1/ +1%/-4%
> 256/ 4/ -1%/-1%
> 256/ 8/ +7%/+5%
> 512/ 1/ +1%/ 0%
> 512/ 4/ +1%/-1%
> 512/ 8/ +7%/-5%
> 1024/ 1/ 0%/-1%
> 1024/ 4/ +3%/ 0%
> 1024/ 8/ +8%/+5%
> 2048/ 1/ +2%/+2%
> 2048/ 4/ +1%/ 0%
> 2048/ 8/ -2%/ 0%
> 4096/ 1/ -2%/ 0%
> 4096/ 4/ +2%/ 0%
> 4096/ 8/ +9%/-2%
>
> Signed-off-by: Haibin Zhang
> Signed-off-by: Yunfang Tai
> Signed-off-by: Lidong Chen
> ---
> drivers/vhost/net.c | 8 +++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 8139bc70ad7d..13a23f3f3ea4 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -44,6 +44,10 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy
> TX;"
> * Using this limit prevents one virtqueue from starving others. */
> #define VHOST_NET_WEIGHT 0x8
>
> +/* Max number of packets transferred before requeueing the job.
> + * Using this limit prevents one virtqueue from starving rx. */
> +#define VHOST_NET_PKT_WEIGHT 512
> +
> /* MAX number of TX used buffers for outstanding zerocopy */
> #define VHOST_MAX_PEND 128
> #define VHOST_GOODCOPY_LEN 256
> @@ -473,6 +477,7 @@ static void handle_tx(struct vhost_net *net)
> struct socket *sock;
> struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
> bool zcopy, zcopy_used;
> + int sent_pkts = 0;
>
> mutex_lock(&vq->mutex);
> sock = vq->private_data;
> @@ -580,7 +585,8 @@ static void handle_tx(struct vhost_net *net)
> else
> vhost_zerocopy_signal_used(net, vq);
> vhost_net_tx_packet(net);
> - if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
> + if (unlikely(total_len >= VHOST_NET_WEIGHT) ||
> + unlikely(++sent_pkts >= VHOST_NET_PKT_WEIGHT)) {
> vhost_poll_queue(&vq->poll);
> break;
> }
> --
> 2.12.3
>
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH] drm/virtio: fix vq wait_event condition
Wait until we have enough space in the virt queue to actually queue up
our request. Avoids the guest spinning in case we have a non-zero
amount of free entries but not enough for the request.
Cc: sta...@vger.kernel.org
Reported-by: Alain Magloire
Signed-off-by: Gerd Hoffmann
---
drivers/gpu/drm/virtio/virtgpu_vq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c
b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 48e4f1df6e..020070d483 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -293,7 +293,7 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct
virtio_gpu_device *vgdev,
ret = virtqueue_add_sgs(vq, sgs, outcnt, incnt, vbuf, GFP_ATOMIC);
if (ret == -ENOSPC) {
spin_unlock(&vgdev->ctrlq.qlock);
- wait_event(vgdev->ctrlq.ack_queue, vq->num_free);
+ wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= outcnt +
incnt);
spin_lock(&vgdev->ctrlq.qlock);
goto retry;
} else {
@@ -368,7 +368,7 @@ static int virtio_gpu_queue_cursor(struct virtio_gpu_device
*vgdev,
ret = virtqueue_add_sgs(vq, sgs, outcnt, 0, vbuf, GFP_ATOMIC);
if (ret == -ENOSPC) {
spin_unlock(&vgdev->cursorq.qlock);
- wait_event(vgdev->cursorq.ack_queue, vq->num_free);
+ wait_event(vgdev->cursorq.ack_queue, vq->num_free >= outcnt);
spin_lock(&vgdev->cursorq.qlock);
goto retry;
} else {
--
2.9.3
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH v30 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT
Negotiation of the VIRTIO_BALLOON_F_FREE_PAGE_HINT feature indicates the
support of reporting hints of guest free pages to host via virtio-balloon.
Host requests the guest to report free page hints by sending a new cmd
id to the guest via the free_page_report_cmd_id configuration register.
When the guest starts to report, the first element added to the free page
vq is the cmd id given by host. When the guest finishes the reporting
of all the free pages, VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID is added
to the vq to tell host that the reporting is done. Host polls the free
page vq after sending the starting cmd id, so the guest doesn't need to
kick after filling an element to the vq.
Host may also requests the guest to stop the reporting in advance by
sending the stop cmd id to the guest via the configuration register.
Signed-off-by: Wei Wang
Signed-off-by: Liang Li
Cc: Michael S. Tsirkin
Cc: Michal Hocko
---
drivers/virtio/virtio_balloon.c | 257 +++-
include/uapi/linux/virtio_balloon.h | 4 +
2 files changed, 225 insertions(+), 36 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index dfe5684..18d24a4 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -51,9 +51,22 @@
static struct vfsmount *balloon_mnt;
#endif
+enum virtio_balloon_vq {
+ VIRTIO_BALLOON_VQ_INFLATE,
+ VIRTIO_BALLOON_VQ_DEFLATE,
+ VIRTIO_BALLOON_VQ_STATS,
+ VIRTIO_BALLOON_VQ_FREE_PAGE,
+ VIRTIO_BALLOON_VQ_MAX
+};
+
struct virtio_balloon {
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
+
+ /* Balloon's own wq for cpu-intensive work items */
+ struct workqueue_struct *balloon_wq;
+ /* The free page reporting work item submitted to the balloon wq */
+ struct work_struct report_free_page_work;
/* The balloon servicing is delegated to a freezable workqueue. */
struct work_struct update_balloon_stats_work;
@@ -63,6 +76,13 @@ struct virtio_balloon {
spinlock_t stop_update_lock;
bool stop_update;
+ /* The new cmd id received from host */
+ uint32_t cmd_id_received;
+ /* The cmd id that is in use */
+ __virtio32 cmd_id_use;
+ /* Buffer to store the stop sign */
+ __virtio32 stop_cmd_id;
+
/* Waiting for host to ack the pages we released. */
wait_queue_head_t acked;
@@ -320,17 +340,6 @@ static void stats_handle_request(struct virtio_balloon *vb)
virtqueue_kick(vq);
}
-static void virtballoon_changed(struct virtio_device *vdev)
-{
- struct virtio_balloon *vb = vdev->priv;
- unsigned long flags;
-
- spin_lock_irqsave(&vb->stop_update_lock, flags);
- if (!vb->stop_update)
- queue_work(system_freezable_wq, &vb->update_balloon_size_work);
- spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-}
-
static inline s64 towards_target(struct virtio_balloon *vb)
{
s64 target;
@@ -347,6 +356,34 @@ static inline s64 towards_target(struct virtio_balloon *vb)
return target - vb->num_pages;
}
+static void virtballoon_changed(struct virtio_device *vdev)
+{
+ struct virtio_balloon *vb = vdev->priv;
+ unsigned long flags;
+ s64 diff = towards_target(vb);
+
+ if (diff) {
+ spin_lock_irqsave(&vb->stop_update_lock, flags);
+ if (!vb->stop_update)
+ queue_work(system_freezable_wq,
+ &vb->update_balloon_size_work);
+ spin_unlock_irqrestore(&vb->stop_update_lock, flags);
+ }
+
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
+ virtio_cread(vdev, struct virtio_balloon_config,
+free_page_report_cmd_id, &vb->cmd_id_received);
+ if (vb->cmd_id_received !=
+ VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID) {
+ spin_lock_irqsave(&vb->stop_update_lock, flags);
+ if (!vb->stop_update)
+ queue_work(vb->balloon_wq,
+ &vb->report_free_page_work);
+ spin_unlock_irqrestore(&vb->stop_update_lock, flags);
+ }
+ }
+}
+
static void update_balloon_size(struct virtio_balloon *vb)
{
u32 actual = vb->num_pages;
@@ -421,42 +458,163 @@ static void update_balloon_size_func(struct work_struct
*work)
static int init_vqs(struct virtio_balloon *vb)
{
- struct virtqueue *vqs[3];
- vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request
};
- static const char * const names[] = { "inflate", "deflate", "stats" };
- int err, nvqs;
+ struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];
+ vq_callback_t *callbacks[V
[PATCH v30 4/4] virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON
The VIRTIO_BALLOON_F_PAGE_POISON feature bit is used to indicate if the
guest is using page poisoning. Guest writes to the poison_val config
field to tell host about the page poisoning value in use.
Signed-off-by: Wei Wang
Suggested-by: Michael S. Tsirkin
Cc: Michael S. Tsirkin
Cc: Michal Hocko
Cc: Andrew Morton
---
drivers/virtio/virtio_balloon.c | 10 ++
include/uapi/linux/virtio_balloon.h | 3 +++
2 files changed, 13 insertions(+)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 18d24a4..6de9339 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -699,6 +699,7 @@ static struct dentry *balloon_mount(struct file_system_type
*fs_type,
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
+ __u32 poison_val;
int err;
if (!vdev->config->get) {
@@ -744,6 +745,11 @@ static int virtballoon_probe(struct virtio_device *vdev)
vb->stop_cmd_id = cpu_to_virtio32(vb->vdev,
VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID);
INIT_WORK(&vb->report_free_page_work, report_free_page_func);
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
+ memset(&poison_val, PAGE_POISON, sizeof(poison_val));
+ virtio_cwrite(vb->vdev, struct virtio_balloon_config,
+ poison_val, &poison_val);
+ }
}
vb->nb.notifier_call = virtballoon_oom_notify;
@@ -862,6 +868,9 @@ static int virtballoon_restore(struct virtio_device *vdev)
static int virtballoon_validate(struct virtio_device *vdev)
{
+ if (!page_poisoning_enabled())
+ __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
+
__virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
return 0;
}
@@ -871,6 +880,7 @@ static int virtballoon_validate(struct virtio_device *vdev)
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
VIRTIO_BALLOON_F_FREE_PAGE_HINT,
+ VIRTIO_BALLOON_F_PAGE_POISON,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h
b/include/uapi/linux/virtio_balloon.h
index b2d86c2..8b93581 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -35,6 +35,7 @@
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM2 /* Deflate balloon on OOM */
#define VIRTIO_BALLOON_F_FREE_PAGE_HINT3 /* VQ to report free pages */
+#define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -47,6 +48,8 @@ struct virtio_balloon_config {
__u32 actual;
/* Free page report command id, readonly by guest */
__u32 free_page_report_cmd_id;
+ /* Stores PAGE_POISON if page poisoning is in use */
+ __u32 poison_val;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
--
1.8.3.1
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH v30 3/4] mm/page_poison: expose page_poisoning_enabled to kernel modules
In some usages, e.g. virtio-balloon, a kernel module needs to know if
page poisoning is in use. This patch exposes the page_poisoning_enabled
function to kernel modules.
Signed-off-by: Wei Wang
Cc: Andrew Morton
Cc: Michal Hocko
Cc: Michael S. Tsirkin
Acked-by: Andrew Morton
---
mm/page_poison.c | 6 ++
1 file changed, 6 insertions(+)
diff --git a/mm/page_poison.c b/mm/page_poison.c
index e83fd44..762b472 100644
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -17,6 +17,11 @@ static int early_page_poison_param(char *buf)
}
early_param("page_poison", early_page_poison_param);
+/**
+ * page_poisoning_enabled - check if page poisoning is enabled
+ *
+ * Return true if page poisoning is enabled, or false if not.
+ */
bool page_poisoning_enabled(void)
{
/*
@@ -29,6 +34,7 @@ bool page_poisoning_enabled(void)
(!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
debug_pagealloc_enabled()));
}
+EXPORT_SYMBOL_GPL(page_poisoning_enabled);
static void poison_page(struct page *page)
{
--
1.8.3.1
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH v30 0/4] Virtio-balloon: support free page reporting
This patch series is separated from the previous "Virtio-balloon Enhancement" series. The new feature, VIRTIO_BALLOON_F_FREE_PAGE_HINT, implemented by this series enables the virtio-balloon driver to report hints of guest free pages to the host. It can be used to accelerate live migration of VMs. Here is an introduction of this usage: Live migration needs to transfer the VM's memory from the source machine to the destination round by round. For the 1st round, all the VM's memory is transferred. From the 2nd round, only the pieces of memory that were written by the guest (after the 1st round) are transferred. One method that is popularly used by the hypervisor to track which part of memory is written is to write-protect all the guest memory. This feature enables the optimization by skipping the transfer of guest free pages during VM live migration. It is not concerned that the memory pages are used after they are given to the hypervisor as a hint of the free pages, because they will be tracked by the hypervisor and transferred in the subsequent round if they are used and written. * Tests - Test Environment Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz Guest: 8G RAM, 4 vCPU Migration setup: migrate_set_speed 100G, migrate_set_downtime 2 second - Test Results - Idle Guest Live Migration Time (results are averaged over 10 runs): - Optimization v.s. Legacy = 271ms vs 1769ms --> ~86% reduction - Guest with Linux Compilation Workload (make bzImage -j4): - Live Migration Time (average) Optimization v.s. Legacy = 1265ms v.s. 2634ms --> ~51% reduction - Linux Compilation Time Optimization v.s. Legacy = 4min56s v.s. 5min3s --> no obvious difference ChangeLog: v29->v30: - mm/walk_free_mem_block: add cond_sched() for each order v28->v29: - mm/page_poison: only expose page_poison_enabled(), rather than more changes did in v28, as we are not 100% confident about that for now. - virtio-balloon: use a separate buffer for the stop cmd, instead of having the start and stop cmd use the same buffer. This avoids the corner case that the start cmd is overridden by the stop cmd when the host has a delay in reading the start cmd. v27->v28: - mm/page_poison: Move PAGE_POISON to page_poison.c and add a function to expose page poison val to kernel modules. v26->v27: - add a new patch to expose page_poisoning_enabled to kernel modules - virtio-balloon: set poison_val to 0x, instead of 0xaa v25->v26: virtio-balloon changes only - remove kicking free page vq since the host now polls the vq after initiating the reporting - report_free_page_func: detach all the used buffers after sending the stop cmd id. This avoids leaving the detaching burden (i.e. overhead) to the next cmd id. Detaching here isn't considered overhead since the stop cmd id has been sent, and host has already moved formard. v24->v25: - mm: change walk_free_mem_block to return 0 (instead of true) on completing the report, and return a non-zero value from the callabck, which stops the reporting. - virtio-balloon: - use enum instead of define for VIRTIO_BALLOON_VQ_INFLATE etc. - avoid __virtio_clear_bit when bailing out; - a new method to avoid reporting the some cmd id to host twice - destroy_workqueue can cancel free page work when the feature is negotiated; - fail probe when the free page vq size is less than 2. v23->v24: - change feature name VIRTIO_BALLOON_F_FREE_PAGE_VQ to VIRTIO_BALLOON_F_FREE_PAGE_HINT - kick when vq->num_free < half full, instead of "= half full" - replace BUG_ON with bailing out - check vb->balloon_wq in probe(), if null, bail out - add a new feature bit for page poisoning - solve the corner case that one cmd id being sent to host twice v22->v23: - change to kick the device when the vq is half-way full; - open-code batch_free_page_sg into add_one_sg; - change cmd_id from "uint32_t" to "__virtio32"; - reserver one entry in the vq for the driver to send cmd_id, instead of busywaiting for an available entry; - add "stop_update" check before queue_work for prudence purpose for now, will have a separate patch to discuss this flag check later; - init_vqs: change to put some variables on stack to have simpler implementation; - add destroy_workqueue(vb->balloon_wq); v21->v22: - add_one_sg: some code and comment re-arrangement - send_cmd_id: handle a cornercase For previous ChangeLog, please reference https://lwn.net/Articles/743660/ Wei Wang (4): mm: support reporting free page blocks virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT mm/page_poison: expose page_poisoning_enabled to kernel modules virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON drivers/virtio/virtio_balloon.c | 267 +
[PATCH v30 1/4] mm: support reporting free page blocks
This patch adds support to walk through the free page blocks in the
system and report them via a callback function. Some page blocks may
leave the free list after zone->lock is released, so it is the caller's
responsibility to either detect or prevent the use of such pages.
One use example of this patch is to accelerate live migration by skipping
the transfer of free pages reported from the guest. A popular method used
by the hypervisor to track which part of memory is written during live
migration is to write-protect all the guest memory. So, those pages that
are reported as free pages but are written after the report function
returns will be captured by the hypervisor, and they will be added to the
next round of memory transfer.
Signed-off-by: Wei Wang
Signed-off-by: Liang Li
Cc: Michal Hocko
Cc: Andrew Morton
Cc: Michael S. Tsirkin
Acked-by: Michal Hocko
---
include/linux/mm.h | 6
mm/page_alloc.c| 97 ++
2 files changed, 103 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ccac106..8141e99 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1942,6 +1942,12 @@ extern void free_area_init_node(int nid, unsigned long *
zones_size,
unsigned long zone_start_pfn, unsigned long *zholes_size);
extern void free_initmem(void);
+extern int walk_free_mem_block(void *opaque,
+ int min_order,
+ int (*report_pfn_range)(void *opaque,
+ unsigned long pfn,
+ unsigned long num));
+
/*
* Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
* into the buddy system. The freed pages will be poisoned with pattern
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4ea0182..83e50fd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4912,6 +4912,103 @@ void show_free_areas(unsigned int filter, nodemask_t
*nodemask)
show_swap_cache_info();
}
+/*
+ * Walk through a free page list and report the found pfn range via the
+ * callback.
+ *
+ * Return 0 if it completes the reporting. Otherwise, return the non-zero
+ * value returned from the callback.
+ */
+static int walk_free_page_list(void *opaque,
+ struct zone *zone,
+ int order,
+ enum migratetype mt,
+ int (*report_pfn_range)(void *,
+ unsigned long,
+ unsigned long))
+{
+ struct page *page;
+ struct list_head *list;
+ unsigned long pfn, flags;
+ int ret = 0;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ list = &zone->free_area[order].free_list[mt];
+ list_for_each_entry(page, list, lru) {
+ pfn = page_to_pfn(page);
+ ret = report_pfn_range(opaque, pfn, 1 << order);
+ if (ret)
+ break;
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ return ret;
+}
+
+/**
+ * walk_free_mem_block - Walk through the free page blocks in the system
+ * @opaque: the context passed from the caller
+ * @min_order: the minimum order of free lists to check
+ * @report_pfn_range: the callback to report the pfn range of the free pages
+ *
+ * If the callback returns a non-zero value, stop iterating the list of free
+ * page blocks. Otherwise, continue to report.
+ *
+ * Please note that there are no locking guarantees for the callback and
+ * that the reported pfn range might be freed or disappear after the
+ * callback returns so the caller has to be very careful how it is used.
+ *
+ * The callback itself must not sleep or perform any operations which would
+ * require any memory allocations directly (not even GFP_NOWAIT/GFP_ATOMIC)
+ * or via any lock dependency. It is generally advisable to implement
+ * the callback as simple as possible and defer any heavy lifting to a
+ * different context.
+ *
+ * There is no guarantee that each free range will be reported only once
+ * during one walk_free_mem_block invocation.
+ *
+ * pfn_to_page on the given range is strongly discouraged and if there is
+ * an absolute need for that make sure to contact MM people to discuss
+ * potential problems.
+ *
+ * The function itself might sleep so it cannot be called from atomic
+ * contexts.
+ *
+ * In general low orders tend to be very volatile and so it makes more
+ * sense to query larger ones first for various optimizations which like
+ * ballooning etc... This will reduce the overhead as well.
+ *
+ * Return 0 if it completes the reporting. Otherwise, return the non-zero
+ * value returned from the callback.
+ */
+int walk_free_mem_block(void *opaque,
+ int min_order,
+ int (*report_pfn_range)(void *opaque
Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
On Sun, Apr 1, 2018 at 9:11 AM, David Ahern wrote: > On 4/1/18 3:13 AM, Si-Wei Liu wrote: >> Hidden netdevice is not visible to userspace such that >> typical network utilities e.g. ip, ifconfig and et al, >> cannot sense its existence or configure it. Internally >> hidden netdev may associate with an upper level netdev >> that userspace has access to. Although userspace cannot >> manipulate the lower netdev directly, user may control >> or configure the underlying hidden device through the >> upper-level netdev. For identification purpose, the >> kobject for hidden netdev still presents in the sysfs >> hierarchy, however, no uevent message will be generated >> when the sysfs entry is created, modified or destroyed. >> >> For that end, a separate namescope needs to be carved >> out for IFF_HIDDEN netdevs. As of now netdev name that >> starts with colon i.e. ':' is invalid in userspace, >> since socket ioctls such as SIOCGIFCONF use ':' as the >> separator for ifname. The absence of namescope started >> with ':' can rightly be used as the namescope for >> the kernel-only IFF_HIDDEN netdevs. >> >> Signed-off-by: Si-Wei Liu >> --- >> include/linux/netdevice.h | 12 ++ >> include/net/net_namespace.h | 2 + >> net/core/dev.c | 281 >> ++-- >> net/core/net_namespace.c| 1 + >> 4 files changed, 263 insertions(+), 33 deletions(-) >> > > There are other use cases that want to hide a device from userspace. Can you elaborate your case in more details? Looking at the links below I realize that the purpose of hiding devices in your case is quite different from the our migration case. Particularly, I don't like the part of elaborately allowing user to manipulate the link's visibility - things fall apart easily while live migration is on going. And, why doing additional check for invisible links in every for_each_netdev() and its friends. This is effectively changing semantics of internal APIs that exist for decades. > I would prefer a better solution than playing games with name prefixes and This part is intentionally left to be that way and I would anticipate feedback before going too far. The idea in my mind was that I need a completely new device namespace underneath (or namescope, which is != netns) for all netdevs: kernel-only IFF_HIDDEN network devices and those not. The current namespace for devname is already exposed to userspace and visible in the sysfs hierarchy, but for backwards compatibility reasons it's necessary to keep the old udevd still able to reference the entry of IFF_HIDDEN netdev under the /sys/net directory. By using the ':' prefix it has the benefit of minimal changes without introducing another namespace or the accompanied complexity in managing these two separate namespaces. Technically, I can create a separate sysfs directory for the new namescope, say /sys/net-kernel, which includes all netdev entries like ':eth0' and 'ens3', and which can be referenced from /sys/net. It would make the /sys/net consistent with the view of userspace utilities, but I am not even sure if that's an overkill, and would like to gather more feedback before moving to that model. > one that includes an API for users to list all devices -- even ones What kind of API you would like to query for hidden devices? rtnetlink? a private socket API? or something else? For our case, the sysfs interface is what we need and is sufficient, since udev is the main target we'd like to support to make the naming of virtio_bypass consistent and compatible. > hidden by default. > > https://github.com/dsahern/linux/commit/48a80a00eac284e58bae04af10a5a932dd7aee00 > > https://github.com/dsahern/iproute2/commit/7563f5b26f5539960e99066e34a995d22ea908ed > > Also, why are you suggesting that the device should still be visible via > /sysfs? That leads to inconsistent views of networking state - /sys > shows a device but a link dump does not. See my clarifications above. I don't mind kernel-only netdevs being visible via sysfs, as that way we get a good trade-off between backwards compatibility and visibility. There's still kobject created there right. Bottom line is that all kernel devices and its life-cycle uevents are made invisible to userpace network utilities, and I think it simply gets to the goal of not breaking existing apps while being able to add new features. -Siwei ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
