Re: KVM "fake DAX" flushing interface - discussion

On Thu, Jan 18, 2018 at 11:51 AM, David Hildenbrand wrote: > >>> 1] Existing pmem driver & virtio for region discovery: >>> - >>> Use existing pmem driver which is tightly coupled with concepts of >>> namespaces, labels

Re: KVM "fake DAX" flushing interface - discussion

>> 1] Existing pmem driver & virtio for region discovery: >> - >> Use existing pmem driver which is tightly coupled with concepts of >> namespaces, labels etc >> from ACPI region discovery and re-implement these concepts with virtio so

Re: KVM "fake DAX" flushing interface - discussion

On Thu, Jan 18, 2018 at 11:36 AM, Pankaj Gupta wrote: > >> >> On Thu, Jan 18, 2018 at 10:54 AM, Pankaj Gupta wrote: >> > >> >> >> >> >> I'd like to emphasize again, that I would prefer a virtio-pmem only >> >> >> solution. >> >> >> >> >> >> There are

Re: KVM "fake DAX" flushing interface - discussion

> > On Thu, Jan 18, 2018 at 10:54 AM, Pankaj Gupta wrote: > > > >> > >> >> I'd like to emphasize again, that I would prefer a virtio-pmem only > >> >> solution. > >> >> > >> >> There are architectures out there (e.g. s390x) that don't support > >> >> NVDIMMs - there is no HW

Re: KVM "fake DAX" flushing interface - discussion

On Thu, Jan 18, 2018 at 10:54 AM, Pankaj Gupta wrote: > >> >> >> I'd like to emphasize again, that I would prefer a virtio-pmem only >> >> solution. >> >> >> >> There are architectures out there (e.g. s390x) that don't support >> >> NVDIMMs - there is no HW interface to expose

Re: KVM "fake DAX" flushing interface - discussion

> > >> I'd like to emphasize again, that I would prefer a virtio-pmem only > >> solution. > >> > >> There are architectures out there (e.g. s390x) that don't support > >> NVDIMMs - there is no HW interface to expose any such stuff. > >> > >> However, with virtio-pmem, we could make it work also

Re: KVM "fake DAX" flushing interface - discussion

On Thu, Jan 18, 2018 at 9:48 AM, David Hildenbrand wrote: >>> I'd like to emphasize again, that I would prefer a virtio-pmem only >>> solution. >>> >>> There are architectures out there (e.g. s390x) that don't support >>> NVDIMMs - there is no HW interface to expose any such

Re: KVM "fake DAX" flushing interface - discussion

>> I'd like to emphasize again, that I would prefer a virtio-pmem only >> solution. >> >> There are architectures out there (e.g. s390x) that don't support >> NVDIMMs - there is no HW interface to expose any such stuff. >> >> However, with virtio-pmem, we could make it work also on architectures

Re: KVM "fake DAX" flushing interface - discussion

Hi Dan, Thanks for your reply. > > On Fri, Jan 12, 2018 at 10:23 PM, Pankaj Gupta wrote: > > > > Hello Dan, > > > >> Not a flag, but a new "Address Range Type GUID". See section "5.2.25.2 > >> System Physical Address (SPA) Range Structure" in the ACPI 6.2A > >>

Re: KVM "fake DAX" flushing interface - discussion

On Fri, Jan 12, 2018 at 10:23 PM, Pankaj Gupta wrote: > > Hello Dan, > >> Not a flag, but a new "Address Range Type GUID". See section "5.2.25.2 >> System Physical Address (SPA) Range Structure" in the ACPI 6.2A >> specification. Since it is a GUID we could define a Linux

Re: KVM "fake DAX" flushing interface - discussion

Hello Dan, > Not a flag, but a new "Address Range Type GUID". See section "5.2.25.2 > System Physical Address (SPA) Range Structure" in the ACPI 6.2A > specification. Since it is a GUID we could define a Linux specific > type for this case, but spec changes would allow non-Linux hypervisors > to

Re: KVM "fake DAX" flushing interface - discussion

On Fri, Nov 24, 2017 at 4:40 AM, Pankaj Gupta wrote: [..] > 1] Expose vNVDIMM memory range to KVM guest. > >- Add flag in ACPI NFIT table for this new memory type. Do we need NVDIMM > spec > changes for this? Not a flag, but a new "Address Range Type GUID". See

Re: [Qemu-devel] KVM "fake DAX" flushing interface - discussion

On 24/11/2017 14:02, Pankaj Gupta wrote: > >>>- Suggestion by Paolo & Stefan(previously) to use virtio-blk makes sense >>>if just >>> want a flush vehicle to send guest commands to host and get reply >>> after asynchronous >>> execution. There was previous discussion [1]

Re: [Qemu-devel] KVM "fake DAX" flushing interface - discussion

> >- Suggestion by Paolo & Stefan(previously) to use virtio-blk makes sense > >if just > > want a flush vehicle to send guest commands to host and get reply > > after asynchronous > > execution. There was previous discussion [1] with Rik & Dan on this. > > > > [1]

Re: KVM "fake DAX" flushing interface - discussion

On 23/11/2017 17:14, Dan Williams wrote: > On Wed, Nov 22, 2017 at 8:05 PM, Xiao Guangrong > wrote: >> >> >> On 11/22/2017 02:19 AM, Rik van Riel wrote: >> >>> We can go with the "best" interface for what >>> could be a relatively slow flush (fsync on a >>> file on

Re: KVM "fake DAX" flushing interface - discussion

On Wed, Nov 22, 2017 at 8:05 PM, Xiao Guangrong wrote: > > > On 11/22/2017 02:19 AM, Rik van Riel wrote: > >> We can go with the "best" interface for what >> could be a relatively slow flush (fsync on a >> file on ssd/disk on the host), which requires >> that the

Re: KVM "fake DAX" flushing interface - discussion

On 11/22/2017 02:19 AM, Rik van Riel wrote: We can go with the "best" interface for what could be a relatively slow flush (fsync on a file on ssd/disk on the host), which requires that the flushing task wait on completion asynchronously. I'd like to clarify the interface of "wait on

Re: KVM "fake DAX" flushing interface - discussion

On Tue, Nov 21, 2017 at 10:19 AM, Rik van Riel wrote: > On Fri, 2017-11-03 at 14:21 +0800, Xiao Guangrong wrote: >> On 11/03/2017 12:30 AM, Dan Williams wrote: >> > >> > Good point, I was assuming that the mmio flush interface would be >> > discovered separately from the

Re: [Qemu-devel] KVM "fake DAX" flushing interface - discussion

> > > > > >> [..] > >> >> Yes, the GUID will specifically identify this range as "Virtio Shared > >> >> Memory" (or whatever name survives after a bikeshed debate). The > >> >> libnvdimm core then needs to grow a new region type that mostly > >> >> behaves the same as a "pmem" region, but

Re: [Qemu-devel] KVM "fake DAX" flushing interface - discussion

> [..] > >> Yes, the GUID will specifically identify this range as "Virtio Shared > >> Memory" (or whatever name survives after a bikeshed debate). The > >> libnvdimm core then needs to grow a new region type that mostly > >> behaves the same as a "pmem" region, but drivers/nvdimm/pmem.c grows a

Re: KVM "fake DAX" flushing interface - discussion

On 11/03/2017 12:30 AM, Dan Williams wrote: On Thu, Nov 2, 2017 at 1:50 AM, Xiao Guangrong wrote: [..] Yes, the GUID will specifically identify this range as "Virtio Shared Memory" (or whatever name survives after a bikeshed debate). The libnvdimm core then

Re: KVM "fake DAX" flushing interface - discussion

On Thu, Nov 2, 2017 at 1:50 AM, Xiao Guangrong wrote: [..] >> Yes, the GUID will specifically identify this range as "Virtio Shared >> Memory" (or whatever name survives after a bikeshed debate). The >> libnvdimm core then needs to grow a new region type that mostly

Re: KVM "fake DAX" flushing interface - discussion

On 11/01/2017 11:20 PM, Dan Williams wrote: On 11/01/2017 12:25 PM, Dan Williams wrote: [..] It's not persistent memory if it requires a hypercall to make it persistent. Unless memory writes can be made durable purely with cpu instructions it's dangerous for it to be treated as a PMEM range.

Re: KVM "fake DAX" flushing interface - discussion

> On 11/01/2017 12:25 PM, Dan Williams wrote: [..] >> It's not persistent memory if it requires a hypercall to make it >> persistent. Unless memory writes can be made durable purely with cpu >> instructions it's dangerous for it to be treated as a PMEM range. >> Consider a guest that tried to map

Re: KVM "fake DAX" flushing interface - discussion

On 11/01/2017 12:25 PM, Dan Williams wrote: On Tue, Oct 31, 2017 at 8:43 PM, Xiao Guangrong wrote: On 10/31/2017 10:20 PM, Dan Williams wrote: On Tue, Oct 31, 2017 at 12:13 AM, Xiao Guangrong wrote: On 07/27/2017 08:54 AM,

Re: KVM "fake DAX" flushing interface - discussion

On Tue, Oct 31, 2017 at 8:43 PM, Xiao Guangrong wrote: > > > On 10/31/2017 10:20 PM, Dan Williams wrote: >> >> On Tue, Oct 31, 2017 at 12:13 AM, Xiao Guangrong >> wrote: >>> >>> >>> >>> On 07/27/2017 08:54 AM, Dan Williams wrote: >>>

Re: KVM "fake DAX" flushing interface - discussion

On 10/31/2017 10:20 PM, Dan Williams wrote: On Tue, Oct 31, 2017 at 12:13 AM, Xiao Guangrong wrote: On 07/27/2017 08:54 AM, Dan Williams wrote: At that point, would it make sense to expose these special virtio-pmem areas to the guest in a slightly different

Re: KVM "fake DAX" flushing interface - discussion

On Tue, Oct 31, 2017 at 12:13 AM, Xiao Guangrong wrote: > > > On 07/27/2017 08:54 AM, Dan Williams wrote: > >>> At that point, would it make sense to expose these special >>> virtio-pmem areas to the guest in a slightly different way, >>> so the regions that need

Re: KVM "fake DAX" flushing interface - discussion

On 07/27/2017 08:54 AM, Dan Williams wrote: At that point, would it make sense to expose these special virtio-pmem areas to the guest in a slightly different way, so the regions that need virtio flushing are not bound by the regular driver, and the regular driver can continue to work for

Re: KVM "fake DAX" flushing interface - discussion

On Wed, Jul 26, 2017 at 4:46 PM, Rik van Riel wrote: > On Wed, 2017-07-26 at 14:40 -0700, Dan Williams wrote: >> On Wed, Jul 26, 2017 at 2:27 PM, Rik van Riel >> wrote: >> > On Wed, 2017-07-26 at 09:47 -0400, Pankaj Gupta wrote: >> > > > >> > > >> > > Just want

Re: KVM "fake DAX" flushing interface - discussion

On Wed, 2017-07-26 at 14:40 -0700, Dan Williams wrote: > On Wed, Jul 26, 2017 at 2:27 PM, Rik van Riel > wrote: > > On Wed, 2017-07-26 at 09:47 -0400, Pankaj Gupta wrote: > > > > > > > > > > Just want to summarize here(high level): > > > > > > This will require implementing

Re: KVM "fake DAX" flushing interface - discussion

> > On Tue, 2017-07-25 at 07:46 -0700, Dan Williams wrote: > > On Tue, Jul 25, 2017 at 7:27 AM, Pankaj Gupta > > wrote: > > > > > > Looks like only way to send flush(blk dev) from guest to host with > > > nvdimm > > > is using flush hint addresses. Is this the correct

Re: KVM "fake DAX" flushing interface - discussion

On Tue, Jul 25, 2017 at 7:27 AM, Pankaj Gupta <pagu...@redhat.com> wrote: > >> Subject: Re: KVM "fake DAX" flushing interface - discussion >> >> On Mon 24-07-17 08:06:07, Pankaj Gupta wrote: >> > >> > > On Sun 23-07-17 13:10:34, Dan Will

Re: KVM "fake DAX" flushing interface - discussion

> Subject: Re: KVM "fake DAX" flushing interface - discussion > > On Mon 24-07-17 08:06:07, Pankaj Gupta wrote: > > > > > On Sun 23-07-17 13:10:34, Dan Williams wrote: > > > > On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel <r...@redhat.com>

Re: KVM "fake DAX" flushing interface - discussion

On Mon, Jul 24, 2017 at 8:48 AM, Jan Kara wrote: > On Mon 24-07-17 08:10:05, Dan Williams wrote: >> On Mon, Jul 24, 2017 at 5:37 AM, Jan Kara wrote: [..] >> This approach would turn into a full fsync on the host. The question >> in my mind is whether there is any

Re: KVM "fake DAX" flushing interface - discussion

On Mon 24-07-17 08:10:05, Dan Williams wrote: > On Mon, Jul 24, 2017 at 5:37 AM, Jan Kara wrote: > > On Mon 24-07-17 08:06:07, Pankaj Gupta wrote: > >> > >> > On Sun 23-07-17 13:10:34, Dan Williams wrote: > >> > > On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel

Re: KVM "fake DAX" flushing interface - discussion

On Mon, Jul 24, 2017 at 5:37 AM, Jan Kara wrote: > On Mon 24-07-17 08:06:07, Pankaj Gupta wrote: >> >> > On Sun 23-07-17 13:10:34, Dan Williams wrote: >> > > On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel wrote: >> > > > On Sun, 2017-07-23 at 09:01 -0700, Dan

Re: KVM "fake DAX" flushing interface - discussion

On Mon 24-07-17 08:06:07, Pankaj Gupta wrote: > > > On Sun 23-07-17 13:10:34, Dan Williams wrote: > > > On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel wrote: > > > > On Sun, 2017-07-23 at 09:01 -0700, Dan Williams wrote: > > > >> [ adding Ross and Jan ] > > > >> > > > >> On Sun,

Re: KVM "fake DAX" flushing interface - discussion

> On Sun 23-07-17 13:10:34, Dan Williams wrote: > > On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel wrote: > > > On Sun, 2017-07-23 at 09:01 -0700, Dan Williams wrote: > > >> [ adding Ross and Jan ] > > >> > > >> On Sun, Jul 23, 2017 at 7:04 AM, Rik van Riel > >

Re: KVM "fake DAX" flushing interface - discussion

On Sun 23-07-17 13:10:34, Dan Williams wrote: > On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel wrote: > > On Sun, 2017-07-23 at 09:01 -0700, Dan Williams wrote: > >> [ adding Ross and Jan ] > >> > >> On Sun, Jul 23, 2017 at 7:04 AM, Rik van Riel > >> wrote: > >>

Re: KVM "fake DAX" flushing interface - discussion

On Sun, Jul 23, 2017 at 11:10 AM, Rik van Riel wrote: > On Sun, 2017-07-23 at 09:01 -0700, Dan Williams wrote: >> [ adding Ross and Jan ] >> >> On Sun, Jul 23, 2017 at 7:04 AM, Rik van Riel >> wrote: >> > >> > The goal is to increase density of guests, by moving

Re: KVM "fake DAX" flushing interface - discussion

On Sun, 2017-07-23 at 09:01 -0700, Dan Williams wrote: > [ adding Ross and Jan ] > > On Sun, Jul 23, 2017 at 7:04 AM, Rik van Riel > wrote: > > > > The goal is to increase density of guests, by moving page > > cache into the host (where it can be easily reclaimed). > > > > If

Re: KVM "fake DAX" flushing interface - discussion

[ adding Ross and Jan ] On Sun, Jul 23, 2017 at 7:04 AM, Rik van Riel wrote: > On Sat, 2017-07-22 at 12:34 -0700, Dan Williams wrote: >> On Fri, Jul 21, 2017 at 8:58 AM, Stefan Hajnoczi > > wrote: >> > >> > Maybe the NVDIMM folks can comment on this idea.

Re: KVM "fake DAX" flushing interface - discussion

On Fri, Jul 21, 2017 at 8:58 AM, Stefan Hajnoczi wrote: > On Fri, Jul 21, 2017 at 09:29:15AM -0400, Pankaj Gupta wrote: >> >> > > A] Problems to solve: >> > > -- >> > > >> > > 1] We are considering two approaches for 'fake DAX flushing interface'. >> > > >> >

Re: KVM "fake DAX" flushing interface - discussion

> > A] Problems to solve: > > -- > > > > 1] We are considering two approaches for 'fake DAX flushing interface'. > > > > 1.1] fake dax with NVDIMM flush hints & KVM async page fault > > > > - Existing interface. > > > > - The approach to use flush hint address

Re: KVM "fake DAX" flushing interface - discussion

> > > > Hello, > > > > We shared a proposal for 'KVM fake DAX flushing interface'. > > > > https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg02478.html > > > > In above link, > "Overall goal of project >is to increase the number of virtual machines that can be >run on a