[ovs-dev] [PATCH v9] dpif-netlink: distribute polling to discreet handlers
Flavio Leitner
fbl at sysclose.org
Tue Oct 27 20:29:25 UTC 2020
On Fri, Sep 18, 2020 at 02:48:17PM -0400, Mark Gray wrote:
> From: Aaron Conole <aconole at redhat.com>
>
> 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 <blp at ovn.org>
> Suggested-by: Flavio Leitner <fbl at sysclose.org>
> Co-authored-by: Mark Gray <mark.d.gray at redhat.com>
> Reported-by: David Ahern <dsahern at gmail.com>
> Reported-at: https://mail.openvswitch.org/pipermail/ovs-dev/2019-December/365857.html
> Cc: Matteo Croce <technoboy85 at gmail.com>
> Fixes: 69c51582f ("dpif-netlink: don't allocate per thread netlink sockets")
> Signed-off-by: Aaron Conole <aconole at redhat.com>
> Signed-off-by: Mark Gray <mark.d.gray at redhat.com>
> ---
>
> 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
> v5: min/avg/max/mdev = 9.3/10.4/33.6/2.2 us
> v6: Split out the AUTHORS patch and added a cover letter as
> per Ilya's suggestion.
> Fixed 0-day issues.
> v7: Merged patches as per Flavio's suggestion. This is
> no longer a series. Fixed some other small issues.
> v9: Udated based on feedback from Ilya. Also implemented
> another suggestion by Flavio
> min/avg/max/mdev = 5.5/11.0/83.2/0.8 us
>
> lib/dpif-netlink.c | 309 ++++++++++++++++++++++-----------------------
> 1 file changed, 149 insertions(+), 160 deletions(-)
>
> diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
> index 7da4fb54d..7e4823ea0 100644
> --- a/lib/dpif-netlink.c
> +++ b/lib/dpif-netlink.c
> @@ -160,8 +160,15 @@ 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 nl_sock *sock; /* Netlink socket. */
> - long long int last_poll; /* Last time this channel was polled. */
> + struct hmap_node handler_node; /* Used by 'struct dpif_handler' to track
> + all channels associated with a
> + handler. */
> + struct hmap_node dpif_node; /* Used by 'struct dpif' to track all dpif
> + channels and their associated port. */
> + struct dpif_handler *handler; /* Pointer to owning 'struct dpif_handler'*/
> + odp_port_t port_no; /* Datapath port number of this channel. */
> + struct nl_sock *sock; /* Netlink socket. */
> + long long int last_poll; /* Last time this channel was polled. */
> };
>
> #ifdef _WIN32
> @@ -183,6 +190,9 @@ 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 associated
> + with this handler. */
> +
> #ifdef _WIN32
> /* Pool of sockets. */
> struct dpif_windows_vport_sock *vport_sock_pool;
> @@ -201,9 +211,7 @@ 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 hmap channels; /* Map of all channels. */
>
> /* Change notification. */
> struct nl_sock *port_notifier; /* vport multicast group subscriber. */
> @@ -287,6 +295,44 @@ 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_channel_find(const struct dpif_netlink *dpif, odp_port_t port_no)
> +{
> + struct dpif_channel *channel;
> +
> + HMAP_FOR_EACH_WITH_HASH (channel, dpif_node,
> + hash_int(odp_to_u32(port_no), 0),
> + &dpif->channels) {
> + if (channel->port_no == port_no) {
> + return channel;
> + }
> + }
> +
> + return NULL;
> +}
> +
> +static void
> +dpif_channel_del(struct dpif_netlink *dpif, struct dpif_channel *channel)
> +{
> + struct dpif_handler *handler = channel->handler;
> +
> +#ifndef _WIN32
> + epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL,
> + nl_sock_fd(channel->sock), NULL);
> + nl_sock_destroy(channel->sock);
> +#endif
> + hmap_remove(&handler->channels, &channel->handler_node);
> + hmap_remove(&dpif->channels, &channel->dpif_node);
> + handler->event_offset = handler->n_events = 0;
> + free(channel);
> +}
> +
> static struct dpif_netlink *
> dpif_netlink_cast(const struct dpif *dpif)
> {
> @@ -385,6 +431,7 @@ open_dpif(const struct dpif_netlink_dp *dp, struct dpif **dpifp)
>
> dpif->dp_ifindex = dp->dp_ifindex;
> dpif->user_features = dp->user_features;
> + hmap_init(&dpif->channels);
> *dpifp = &dpif->dpif;
>
> return 0;
> @@ -446,153 +493,122 @@ error:
> }
> #endif /* _WIN32 */
>
> -/* Given the port number 'port_idx', extracts the pid of netlink socket
> +/* Given the port number 'port_no', extracts the pid of netlink socket
> * associated to the port and assigns it to 'upcall_pid'. */
> static bool
> -vport_get_pid(struct dpif_netlink *dpif, uint32_t port_idx,
> +vport_get_pid(const struct dpif_netlink *dpif, odp_port_t port_no,
> 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) {
> - return false;
> - }
> - ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
> + struct dpif_channel *channel;
>
> - *upcall_pid = nl_sock_pid(dpif->channels[port_idx].sock);
> + ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
>
> - return true;
> + channel = dpif_channel_find(dpif, port_no);
> + if (channel) {
> + *upcall_pid = nl_sock_pid(channel->sock);
> + return true;
> + }
> + return false;
> }
>
> static int
> vport_add_channel(struct dpif_netlink *dpif, odp_port_t port_no,
> struct nl_sock *sock)
> {
> + struct dpif_channel *channel;
> + struct dpif_handler *handler;
> struct epoll_event event;
> - uint32_t port_idx = odp_to_u32(port_no);
> size_t i;
> - int error;
>
> - if (dpif->handlers == NULL) {
> + if (dpif->handlers == NULL || dpif_channel_find(dpif, port_no)) {
> close_nl_sock(sock);
I know this code was already there, but it seems odd to have
this function to close the sock in case of error. It should
be the parent, if needed, to do that.
Also, we have some returns below which don't do that, so it's
not a common action.
> - 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) {
> - VLOG_WARN_RL(&error_rl, "%s: datapath port %"PRIu32" too big",
> - dpif_name(&dpif->dpif), port_no);
> - return EFBIG;
> - }
> + if (odp_to_u32(port_no) >= 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);
> + handler = &dpif->handlers[0];
>
> - for (i = dpif->uc_array_size; i < new_size; i++) {
> - dpif->channels[i].sock = NULL;
> + 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];
> }
> + }
>
> - for (i = 0; i < dpif->n_handlers; i++) {
> - struct dpif_handler *handler = &dpif->handlers[i];
> -
> - handler->epoll_events = xrealloc(handler->epoll_events,
> - new_size * sizeof *handler->epoll_events);
> + channel = xmalloc(sizeof *channel);
> + channel->port_no = port_no;
> + channel->sock = sock;
> + channel->last_poll = LLONG_MIN;
> + channel->handler = handler;
> + hmap_insert(&handler->channels, &channel->handler_node,
> + hash_int(odp_to_u32(port_no), 0));
> + hmap_insert(&dpif->channels, &channel->dpif_node,
> + hash_int(odp_to_u32(port_no), 0));
>
> - }
> - dpif->uc_array_size = new_size;
> - }
> + handler->epoll_events = xrealloc(handler->epoll_events,
> + dpif_handler_channels_count(handler) *
> + sizeof *handler->epoll_events);
The epoll_events is only needed by epoll_wait() which is only
useful if epoll_ctl() succeed, so that xrealloc() could be
done only after epoll_ctl() succeed.
> 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];
> + event.data.u32 = odp_to_u32(port_no);
I think the above code initializing event could be moved to the
#ifndef below, including the xrealloc() since they are all
related and they are not large.
>
> #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) {
> + hmap_remove(&handler->channels, &channel->handler_node);
> + hmap_remove(&dpif->channels, &channel->dpif_node);
> + free(channel);
Here is one example of returning error without closing the sock.
> + return errno;
> }
> #endif
> - dpif->channels[port_idx].sock = NULL;
>
> - return error;
> + return 0;
> }
>
> -static void
> -vport_del_channels(struct dpif_netlink *dpif, odp_port_t port_no)
> +static bool
> +vport_del_channel(struct dpif_netlink *dpif, odp_port_t port_no)
> {
> - uint32_t port_idx = odp_to_u32(port_no);
> - size_t i;
> + struct dpif_channel *channel;
>
> - if (!dpif->handlers || port_idx >= dpif->uc_array_size
> - || !dpif->channels[port_idx].sock) {
> - return;
> + channel = dpif_channel_find(dpif, port_no);
> + if (channel) {
> + dpif_channel_del(dpif, channel);
> + return true;
> }
>
> - for (i = 0; i < dpif->n_handlers; i++) {
> - struct dpif_handler *handler = &dpif->handlers[i];
> -#ifndef _WIN32
> - epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL,
> - nl_sock_fd(dpif->channels[port_idx].sock), NULL);
> -#endif
> - handler->event_offset = handler->n_events = 0;
> - }
> -#ifndef _WIN32
> - nl_sock_destroy(dpif->channels[port_idx].sock);
> -#endif
> - dpif->channels[port_idx].sock = NULL;
> + return false;
> }
>
> static void
> destroy_all_channels(struct dpif_netlink *dpif)
> OVS_REQ_WRLOCK(dpif->upcall_lock)
> {
> - unsigned int i;
> + struct dpif_channel *channel, *next;
> + size_t i;
>
> if (!dpif->handlers) {
> return;
> }
>
> - for (i = 0; i < dpif->uc_array_size; i++ ) {
> + HMAP_FOR_EACH_SAFE (channel, next, dpif_node, &dpif->channels) {
> 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.port_no = channel->port_no;
> 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));
> + dpif_channel_del(dpif, channel);
> }
>
> for (i = 0; i < dpif->n_handlers; i++) {
> @@ -601,12 +617,10 @@ destroy_all_channels(struct dpif_netlink *dpif)
> 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 +632,11 @@ dpif_netlink_close(struct dpif *dpif_)
>
> fat_rwlock_wrlock(&dpif->upcall_lock);
> destroy_all_channels(dpif);
> + hmap_destroy(&dpif->channels);
> fat_rwlock_unlock(&dpif->upcall_lock);
>
> fat_rwlock_destroy(&dpif->upcall_lock);
> +
> free(dpif);
> }
>
> @@ -1002,9 +1018,6 @@ dpif_netlink_port_del__(struct dpif_netlink *dpif, odp_port_t port_no)
> }
> #endif
> error = dpif_netlink_vport_transact(&vport, NULL, NULL);
> -
> - vport_del_channels(dpif, port_no);
> -
> if (!error && !ovs_tunnels_out_of_tree) {
> error = dpif_netlink_rtnl_port_destroy(dpif_port.name, dpif_port.type);
> if (error == EOPNOTSUPP) {
> @@ -1012,6 +1025,10 @@ dpif_netlink_port_del__(struct dpif_netlink *dpif, odp_port_t port_no)
> }
> }
>
> + if (!vport_del_channel(dpif, port_no)) {
> + error = EINVAL;
> + }
> +
> dpif_port_destroy(&dpif_port);
>
> return error;
> @@ -1080,41 +1097,27 @@ dpif_netlink_port_query_by_name(const struct dpif *dpif_, const char *devname,
> }
>
> static uint32_t
> -dpif_netlink_port_get_pid__(const struct dpif_netlink *dpif,
> - odp_port_t port_no)
> - OVS_REQ_RDLOCK(dpif->upcall_lock)
> +dpif_netlink_port_get_pid(const struct dpif *dpif_, odp_port_t port)
> {
> - uint32_t port_idx = odp_to_u32(port_no);
> + const struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
> uint32_t pid = 0;
> + odp_port_t port_no = port;
The port_no initialized above is initialized again right after
that.
>
> - 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);
> - }
> - }
> -
> - return pid;
> -}
> -
> -static uint32_t
> -dpif_netlink_port_get_pid(const struct dpif *dpif_, odp_port_t port_no)
> -{
> - const struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
> - uint32_t ret;
> + /* The ODPP_NONE "reserved" port number uses the "ovs-system"'s
> + * channel, since it is not heavily loaded. */
> + port_no = port == ODPP_NONE ? u32_to_odp(0) : port;
Here.
>
> fat_rwlock_rdlock(&dpif->upcall_lock);
> - ret = dpif_netlink_port_get_pid__(dpif, port_no);
> + /* Try to find the PID associated with 'port no'. If we fail, we can fall
> + back to the system channel PID, or return 0 indicating a failure. */
> + if (!vport_get_pid(dpif, port_no, &pid)) {
> + if (!vport_get_pid(dpif, 0, &pid)) {
> + pid = 0;
> + }
> + }
> fat_rwlock_unlock(&dpif->upcall_lock);
>
> - return ret;
> + return pid;
> }
>
> static int
> @@ -2342,12 +2345,14 @@ 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 +2360,7 @@ 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 +2368,7 @@ 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 +2381,7 @@ 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;
> @@ -2416,18 +2421,13 @@ 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)) {
> - uint32_t port_no = odp_to_u32(vport.port_no);
> 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, vport.port_no, &upcall_pid)) {
> struct nl_sock *sock;
> error = create_nl_sock(dpif, &sock);
>
> @@ -2475,25 +2475,15 @@ 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:
> - vport_del_channels(dpif, vport.port_no);
> + vport_del_channel(dpif, vport.port_no);
> }
> +
> 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 +2704,8 @@ 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 +2713,15 @@ 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 +2734,9 @@ 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_channel_find(dpif, u32_to_odp(idx));
> + ovs_assert(ch != NULL);
> + ovs_assert(ch->handler == handler);
>
> handler->event_offset++;
>
> @@ -2842,16 +2837,10 @@ static void
> dpif_netlink_recv_purge__(struct dpif_netlink *dpif)
> OVS_REQ_WRLOCK(dpif->upcall_lock)
> {
> - if (dpif->handlers) {
> - size_t i;
> + struct dpif_channel *channel;
>
> - if (!dpif->channels[0].sock) {
> - return;
> - }
> - for (i = 0; i < dpif->uc_array_size; i++ ) {
> -
> - nl_sock_drain(dpif->channels[i].sock);
> - }
> + HMAP_FOR_EACH (channel, dpif_node, &dpif->channels) {
> + nl_sock_drain(channel->sock);
> }
> }
The above function is so small now that I would suggest to
add the code to dpif_netlink_recv_purge().
Thanks,
--
fbl
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