Mark,
This patch is v4 and 2/3. Before it was only one patch, so I wonder if v4 is only one patch, or if this has multiple patches (2/3). BTW, differently from DPDK community, we start new threads for new patch versions. fbl On Fri, Aug 28, 2020 at 06:03:04PM +0100, Mark Gray wrote: > From: Aaron Conole <[email protected]> > > Currently, the channel handlers are polled globally. On some > systems, this causes a thundering herd issue where multiple > handler threads become active, only to do no work and immediately > sleep. > > The approach here is to push the netlink socket channels to discreet > handler threads to process, rather than polling on every thread. > This will eliminate the need to wake multiple threads. > > To check: > > ip netns add left > ip netns add right > ip link add center-left type veth peer name left0 netns left > ip link add center-right type veth peer name right0 netns right > ip link set center-left up > ip link set center-right up > ip -n left ip link set left0 up > ip -n left ip addr add 172.31.110.10/24 dev left0 > ip -n right ip link set right0 up > ip -n right ip addr add 172.31.110.11/24 dev right0 > > ovs-vsctl add-br br0 > ovs-vsctl add-port br0 center-right > ovs-vsctl add-port br0 center-left > > # in one terminal > perf record -e sched:sched_wakeup,irq:softirq_entry -ag > > # in a separate terminal > ip netns exec left arping -I left0 -c 1 172.31.110.11 > > # in the perf terminal after exiting > perf script > > Look for the number of 'handler' threads which were made active. > > Suggested-by: Ben Pfaff <[email protected]> > Co-authored-by: Mark Gray <[email protected]> > Reported-by: David Ahern <[email protected]> > Reported-at: > https://mail.openvswitch.org/pipermail/ovs-dev/2019-December/365857.html > Cc: Matteo Croce <[email protected]> > Cc: Flavio Leitner <[email protected]> > Fixes: 69c51582f ("dpif-netlink: don't allocate per thread netlink sockets") > Signed-off-by: Aaron Conole <[email protected]> > Signed-off-by: Mark Gray <[email protected]> > --- > v2: Oops - forgot to commit my whitespace cleanups. > v3: one port latency results as per Matteo's comments > > Stock: > min/avg/max/mdev = 21.5/36.5/96.5/1.0 us > With Patch: > min/avg/max/mdev = 5.3/9.7/98.4/0.5 us > v4: Oops - first email did not send > > lib/dpif-netlink.c | 311 ++++++++++++++++++++++++++------------------- > 1 file changed, 182 insertions(+), 129 deletions(-) > > diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c > index 7da4fb54d..d928d7aa1 100644 > --- a/lib/dpif-netlink.c > +++ b/lib/dpif-netlink.c > @@ -37,6 +37,7 @@ > #include "dpif-provider.h" > #include "fat-rwlock.h" > #include "flow.h" > +#include "id-pool.h" > #include "netdev-linux.h" > #include "netdev-offload.h" > #include "netdev-provider.h" > @@ -160,6 +161,8 @@ static void dpif_netlink_flow_to_dpif_flow(struct > dpif_flow *, > > /* One of the dpif channels between the kernel and userspace. */ > struct dpif_channel { > + struct hmap_node hmap_node; > + uint32_t port_idx; > struct nl_sock *sock; /* Netlink socket. */ > long long int last_poll; /* Last time this channel was polled. */ > }; > @@ -183,6 +186,8 @@ struct dpif_handler { > int n_events; /* Num events returned by epoll_wait(). */ > int event_offset; /* Offset into 'epoll_events'. */ > > + struct hmap channels; /* map of channels for each port. */ > + > #ifdef _WIN32 > /* Pool of sockets. */ > struct dpif_windows_vport_sock *vport_sock_pool; > @@ -201,9 +206,8 @@ struct dpif_netlink { > struct fat_rwlock upcall_lock; > struct dpif_handler *handlers; > uint32_t n_handlers; /* Num of upcall handlers. */ > - struct dpif_channel *channels; /* Array of channels for each port. */ > - int uc_array_size; /* Size of 'handler->channels' and */ > - /* 'handler->epoll_events'. */ > + > + struct id_pool *port_ids; /* Set of added port ids */ > > /* Change notification. */ > struct nl_sock *port_notifier; /* vport multicast group subscriber. */ > @@ -287,6 +291,53 @@ close_nl_sock(struct nl_sock *sock) > #endif > } > > +static size_t > +dpif_handler_channels_count(const struct dpif_handler *handler) > +{ > + return hmap_count(&handler->channels); > +} > + > +static struct dpif_channel * > +dpif_handler_channel_get(struct dpif_handler *handler, uint32_t idx) > +{ > + struct dpif_channel *channel; > + > + HMAP_FOR_EACH_WITH_HASH (channel, hmap_node, hash_int(idx, 0), > + &handler->channels) { > + if (channel->port_idx == idx) { > + return channel; > + } > + } > + > + return NULL; > +} > + > +static void > +dpif_handler_channel_add(struct dpif_handler *handler, uint32_t idx, > + struct nl_sock *sock) > +{ > + struct dpif_channel *channel = xmalloc(sizeof *channel); > + > + channel->port_idx = idx; > + channel->sock = sock; > + channel->last_poll = LLONG_MIN; > + > + hmap_insert(&handler->channels, &channel->hmap_node, hash_int(idx,0)); > +} > + > +static void > +dpif_handler_channel_del(struct dpif_handler *handler, uint32_t port_idx) > +{ > + struct dpif_channel *channel = dpif_handler_channel_get(handler, > port_idx); > + > + hmap_remove(&(handler->channels), &(channel->hmap_node)); > + > + free(channel); > +} > + > + > + > + > static struct dpif_netlink * > dpif_netlink_cast(const struct dpif *dpif) > { > @@ -385,6 +436,11 @@ open_dpif(const struct dpif_netlink_dp *dp, struct dpif > **dpifp) > > dpif->dp_ifindex = dp->dp_ifindex; > dpif->user_features = dp->user_features; > + dpif->port_ids = id_pool_create(0, MAX_PORTS); > + if (!dpif->port_ids) { > + return ENOMEM; > + } > + > *dpifp = &dpif->dpif; > > return 0; > @@ -452,161 +508,144 @@ static bool > vport_get_pid(struct dpif_netlink *dpif, uint32_t port_idx, > uint32_t *upcall_pid) > { > - /* Since the nl_sock can only be assigned in either all > - * or none "dpif" channels, the following check > - * would suffice. */ > - if (!dpif->channels[port_idx].sock) { > + size_t i; > + ovs_assert(!WINDOWS || dpif->n_handlers <= 1); > + > + if (!id_pool_check(dpif->port_ids, port_idx)) { > return false; > } > - ovs_assert(!WINDOWS || dpif->n_handlers <= 1); > > - *upcall_pid = nl_sock_pid(dpif->channels[port_idx].sock); > + /* The 'port_idx' should only be valid for a single handler. */ > + for (i = 0; i < dpif->n_handlers; i++) { > + struct dpif_channel *channel = > + dpif_handler_channel_get(&dpif->handlers[i], port_idx); > + > + if (channel) { > + *upcall_pid = nl_sock_pid(channel->sock); > + return true; > + } > + } > > - return true; > + return false; > } > > static int > vport_add_channel(struct dpif_netlink *dpif, odp_port_t port_no, > struct nl_sock *sock) > { > - struct epoll_event event; > uint32_t port_idx = odp_to_u32(port_no); > + struct dpif_handler *handler; > + struct epoll_event event; > size_t i; > - int error; > > - if (dpif->handlers == NULL) { > + if (dpif->handlers == NULL || > + id_pool_check(dpif->port_ids, port_idx)) { > close_nl_sock(sock); > - return 0; > + return EINVAL; > } > > - /* We assume that the datapath densely chooses port numbers, which can > - * therefore be used as an index into 'channels' and 'epoll_events' of > - * 'dpif'. */ > - if (port_idx >= dpif->uc_array_size) { > - uint32_t new_size = port_idx + 1; > - > - if (new_size > MAX_PORTS) { > + if (port_idx >= MAX_PORTS) { > VLOG_WARN_RL(&error_rl, "%s: datapath port %"PRIu32" too big", > dpif_name(&dpif->dpif), port_no); > return EFBIG; > - } > - > - dpif->channels = xrealloc(dpif->channels, > - new_size * sizeof *dpif->channels); > + } > > - for (i = dpif->uc_array_size; i < new_size; i++) { > - dpif->channels[i].sock = NULL; > - } > + handler = &dpif->handlers[0]; > > - for (i = 0; i < dpif->n_handlers; i++) { > - struct dpif_handler *handler = &dpif->handlers[i]; > + for (i = 0; i < dpif->n_handlers; i++) { > + if (dpif_handler_channels_count(&dpif->handlers[i]) < > + dpif_handler_channels_count(handler)) > + handler = &dpif->handlers[i]; > + } > > - handler->epoll_events = xrealloc(handler->epoll_events, > - new_size * sizeof *handler->epoll_events); > + dpif_handler_channel_add(handler, port_idx, sock); > > - } > - dpif->uc_array_size = new_size; > - } > + handler->epoll_events = xrealloc(handler->epoll_events, > + dpif_handler_channels_count(handler) > * > + sizeof *handler->epoll_events); > > memset(&event, 0, sizeof event); > event.events = EPOLLIN | EPOLLEXCLUSIVE; > event.data.u32 = port_idx; > > - for (i = 0; i < dpif->n_handlers; i++) { > - struct dpif_handler *handler = &dpif->handlers[i]; > - > #ifndef _WIN32 > - if (epoll_ctl(handler->epoll_fd, EPOLL_CTL_ADD, nl_sock_fd(sock), > - &event) < 0) { > - error = errno; > - goto error; > - } > -#endif > - } > - dpif->channels[port_idx].sock = sock; > - dpif->channels[port_idx].last_poll = LLONG_MIN; > - > - return 0; > - > -error: > -#ifndef _WIN32 > - while (i--) { > - epoll_ctl(dpif->handlers[i].epoll_fd, EPOLL_CTL_DEL, > - nl_sock_fd(sock), NULL); > + if (epoll_ctl(handler->epoll_fd, EPOLL_CTL_ADD, nl_sock_fd(sock), > + &event) < 0) { > + dpif_handler_channel_del(handler, port_idx); > + id_pool_free_id(dpif->port_ids, port_idx); > + return errno; > } > #endif > - dpif->channels[port_idx].sock = NULL; > > - return error; > + id_pool_add(dpif->port_ids, port_idx); > + return 0; > } > > static void > vport_del_channels(struct dpif_netlink *dpif, odp_port_t port_no) > { > uint32_t port_idx = odp_to_u32(port_no); > + struct dpif_handler *handler = NULL; > + struct dpif_channel *channel = NULL; > size_t i; > > - if (!dpif->handlers || port_idx >= dpif->uc_array_size > - || !dpif->channels[port_idx].sock) { > + if (!dpif->handlers) { > return; > } > > for (i = 0; i < dpif->n_handlers; i++) { > - struct dpif_handler *handler = &dpif->handlers[i]; > + handler = &dpif->handlers[i]; > + channel = dpif_handler_channel_get(handler, port_idx); > + > + if (channel) { > #ifndef _WIN32 > - epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL, > - nl_sock_fd(dpif->channels[port_idx].sock), NULL); > + epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL, > + nl_sock_fd(channel->sock), NULL); > + nl_sock_destroy(channel->sock); > #endif > - handler->event_offset = handler->n_events = 0; > + dpif_handler_channel_del(handler, port_idx); > + id_pool_free_id(dpif->port_ids, port_idx); > + handler->event_offset = handler->n_events = 0; > + break; > + } > } > -#ifndef _WIN32 > - nl_sock_destroy(dpif->channels[port_idx].sock); > -#endif > - dpif->channels[port_idx].sock = NULL; > } > > static void > destroy_all_channels(struct dpif_netlink *dpif) > OVS_REQ_WRLOCK(dpif->upcall_lock) > { > - unsigned int i; > + size_t i; > > if (!dpif->handlers) { > return; > } > > - for (i = 0; i < dpif->uc_array_size; i++ ) { > - struct dpif_netlink_vport vport_request; > - uint32_t upcall_pids = 0; > - > - if (!dpif->channels[i].sock) { > - continue; > - } > - > - /* Turn off upcalls. */ > - dpif_netlink_vport_init(&vport_request); > - vport_request.cmd = OVS_VPORT_CMD_SET; > - vport_request.dp_ifindex = dpif->dp_ifindex; > - vport_request.port_no = u32_to_odp(i); > - vport_request.n_upcall_pids = 1; > - vport_request.upcall_pids = &upcall_pids; > - dpif_netlink_vport_transact(&vport_request, NULL, NULL); > - > - vport_del_channels(dpif, u32_to_odp(i)); > - } > - > for (i = 0; i < dpif->n_handlers; i++) { > struct dpif_handler *handler = &dpif->handlers[i]; > + struct dpif_channel *channel, *next; > + > + HMAP_FOR_EACH_SAFE (channel, next, hmap_node, &handler->channels) { > + struct dpif_netlink_vport vport_request; > + uint32_t upcall_pids = 0; > + /* Turn off upcalls. */ > + dpif_netlink_vport_init(&vport_request); > + vport_request.cmd = OVS_VPORT_CMD_SET; > + vport_request.dp_ifindex = dpif->dp_ifindex; > + vport_request.port_no = u32_to_odp(channel->port_idx); > + vport_request.n_upcall_pids = 1; > + vport_request.upcall_pids = &upcall_pids; > + dpif_netlink_vport_transact(&vport_request, NULL, NULL); > + > + vport_del_channels(dpif, u32_to_odp(channel->port_idx)); > + } > > dpif_netlink_handler_uninit(handler); > free(handler->epoll_events); > } > - free(dpif->channels); > - free(dpif->handlers); > + > dpif->handlers = NULL; > - dpif->channels = NULL; > dpif->n_handlers = 0; > - dpif->uc_array_size = 0; > } > > static void > @@ -618,9 +657,11 @@ dpif_netlink_close(struct dpif *dpif_) > > fat_rwlock_wrlock(&dpif->upcall_lock); > destroy_all_channels(dpif); > + id_pool_destroy(dpif->port_ids); > fat_rwlock_unlock(&dpif->upcall_lock); > > fat_rwlock_destroy(&dpif->upcall_lock); > + > free(dpif); > } > > @@ -1084,23 +1125,40 @@ dpif_netlink_port_get_pid__(const struct dpif_netlink > *dpif, > odp_port_t port_no) > OVS_REQ_RDLOCK(dpif->upcall_lock) > { > + struct dpif_channel *min_channel = NULL, *found_channel = NULL; > uint32_t port_idx = odp_to_u32(port_no); > uint32_t pid = 0; > + size_t i; > + > + /* The ODPP_NONE "reserved" port number uses the "ovs-system"'s > + * channel, since it is not heavily loaded. */ > + uint32_t idx = port_no == ODPP_NONE ? 0 : port_idx; > + > + if (!id_pool_check(dpif->port_ids, port_idx)) { > + return 0; > + } > + > + if (dpif->handlers) { > + for (i = 0; i < dpif->n_handlers; i++) { > + if (dpif_handler_channel_get(&dpif->handlers[i], idx)) { > + found_channel = dpif_handler_channel_get(&dpif->handlers[i], > + idx); > + break; > + } > > - if (dpif->handlers && dpif->uc_array_size > 0) { > - /* The ODPP_NONE "reserved" port number uses the "ovs-system"'s > - * channel, since it is not heavily loaded. */ > - uint32_t idx = port_idx >= dpif->uc_array_size ? 0 : port_idx; > - > - /* Needs to check in case the socket pointer is changed in between > - * the holding of upcall_lock. A known case happens when the main > - * thread deletes the vport while the handler thread is handling > - * the upcall from that port. */ > - if (dpif->channels[idx].sock) { > - pid = nl_sock_pid(dpif->channels[idx].sock); > + if (dpif_handler_channel_get(&dpif->handlers[i], 0)) { > + min_channel = dpif_handler_channel_get(&dpif->handlers[i], > + 0); > + } > } > } > > + if (found_channel) { > + pid = nl_sock_pid(found_channel->sock); > + } else if (min_channel) { > + pid = nl_sock_pid(min_channel->sock); > + } > + > return pid; > } > > @@ -2342,12 +2400,14 @@ dpif_netlink_operate(struct dpif *dpif_, struct > dpif_op **ops, size_t n_ops, > static void > dpif_netlink_handler_uninit(struct dpif_handler *handler) > { > + hmap_destroy(&handler->channels); > vport_delete_sock_pool(handler); > } > > static int > dpif_netlink_handler_init(struct dpif_handler *handler) > { > + hmap_init(&handler->channels); > return vport_create_sock_pool(handler); > } > #else > @@ -2355,6 +2415,7 @@ dpif_netlink_handler_init(struct dpif_handler *handler) > static int > dpif_netlink_handler_init(struct dpif_handler *handler) > { > + hmap_init(&handler->channels); > handler->epoll_fd = epoll_create(10); > return handler->epoll_fd < 0 ? errno : 0; > } > @@ -2362,6 +2423,7 @@ dpif_netlink_handler_init(struct dpif_handler *handler) > static void > dpif_netlink_handler_uninit(struct dpif_handler *handler) > { > + hmap_destroy(&handler->channels); > close(handler->epoll_fd); > } > #endif > @@ -2374,9 +2436,7 @@ static int > dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers) > OVS_REQ_WRLOCK(dpif->upcall_lock) > { > - unsigned long int *keep_channels; > struct dpif_netlink_vport vport; > - size_t keep_channels_nbits; > struct nl_dump dump; > uint64_t reply_stub[NL_DUMP_BUFSIZE / 8]; > struct ofpbuf buf; > @@ -2416,9 +2476,6 @@ dpif_netlink_refresh_channels(struct dpif_netlink > *dpif, uint32_t n_handlers) > handler->event_offset = handler->n_events = 0; > } > > - keep_channels_nbits = dpif->uc_array_size; > - keep_channels = bitmap_allocate(keep_channels_nbits); > - > ofpbuf_use_stub(&buf, reply_stub, sizeof reply_stub); > dpif_netlink_port_dump_start__(dpif, &dump); > while (!dpif_netlink_port_dump_next__(dpif, &dump, &vport, &buf)) { > @@ -2426,8 +2483,7 @@ dpif_netlink_refresh_channels(struct dpif_netlink > *dpif, uint32_t n_handlers) > uint32_t upcall_pid; > int error; > > - if (port_no >= dpif->uc_array_size > - || !vport_get_pid(dpif, port_no, &upcall_pid)) { > + if (!vport_get_pid(dpif, port_no, &upcall_pid)) { > struct nl_sock *sock; > error = create_nl_sock(dpif, &sock); > > @@ -2475,9 +2531,6 @@ dpif_netlink_refresh_channels(struct dpif_netlink > *dpif, uint32_t n_handlers) > } > } > > - if (port_no < keep_channels_nbits) { > - bitmap_set1(keep_channels, port_no); > - } > continue; > > error: > @@ -2486,14 +2539,6 @@ dpif_netlink_refresh_channels(struct dpif_netlink > *dpif, uint32_t n_handlers) > nl_dump_done(&dump); > ofpbuf_uninit(&buf); > > - /* Discard any saved channels that we didn't reuse. */ > - for (i = 0; i < keep_channels_nbits; i++) { > - if (!bitmap_is_set(keep_channels, i)) { > - vport_del_channels(dpif, u32_to_odp(i)); > - } > - } > - free(keep_channels); > - > return retval; > } > > @@ -2714,6 +2759,8 @@ dpif_netlink_recv__(struct dpif_netlink *dpif, uint32_t > handler_id, > OVS_REQ_RDLOCK(dpif->upcall_lock) > { > struct dpif_handler *handler; > + size_t n_channels; > + > int read_tries = 0; > > if (!dpif->handlers || handler_id >= dpif->n_handlers) { > @@ -2721,14 +2768,15 @@ dpif_netlink_recv__(struct dpif_netlink *dpif, > uint32_t handler_id, > } > > handler = &dpif->handlers[handler_id]; > - if (handler->event_offset >= handler->n_events) { > + n_channels = dpif_handler_channels_count(handler); > + if (handler->event_offset >= handler->n_events && n_channels) { > int retval; > > handler->event_offset = handler->n_events = 0; > > do { > retval = epoll_wait(handler->epoll_fd, handler->epoll_events, > - dpif->uc_array_size, 0); > + n_channels, 0); > } while (retval < 0 && errno == EINTR); > > if (retval < 0) { > @@ -2741,7 +2789,10 @@ dpif_netlink_recv__(struct dpif_netlink *dpif, > uint32_t handler_id, > > while (handler->event_offset < handler->n_events) { > int idx = handler->epoll_events[handler->event_offset].data.u32; > - struct dpif_channel *ch = &dpif->channels[idx]; > + struct dpif_channel *ch = dpif_handler_channel_get(handler, idx); > + if (!ch) { > + return EAGAIN; > + } > > handler->event_offset++; > > @@ -2845,12 +2896,14 @@ dpif_netlink_recv_purge__(struct dpif_netlink *dpif) > if (dpif->handlers) { > size_t i; > > - if (!dpif->channels[0].sock) { > - return; > - } > - for (i = 0; i < dpif->uc_array_size; i++ ) { > + for (i = 0; i < dpif->n_handlers; i++) { > + struct dpif_handler *handler = &dpif->handlers[i]; > + struct dpif_channel *channel; > + > + HMAP_FOR_EACH (channel, hmap_node, &handler->channels) { > + nl_sock_drain(channel->sock); > + } > > - nl_sock_drain(dpif->channels[i].sock); > } > } > } > -- > 2.26.2 > -- fbl _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
