[ovs-dev] [PATCH] dpif-netlink: don't allocate per thread netlink sockets
Matteo Croce
mcroce at redhat.com
Wed Sep 19 12:47:03 UTC 2018
When using the kernel datapath, OVS allocates a pool of sockets to handle
netlink events. The number of sockets is: ports * n-handler-threads, where
n-handler-threads is user configurable and defaults to 3/4*number of cores.
This because vswitchd starts n-handler-threads threads, each one with a
netlink socket for every port of the switch. Every thread then, starts
listening on events on its set of sockets with epoll().
On setup with lot of CPUs and ports, the number of sockets easily hits
the process file descriptor limit, and ovs-vswitchd will exit with -EMFILE.
Change the number of allocated sockets to just one per port by moving
the socket array from a per handler structure to a per datapath one,
and let all the handlers share the same sockets by using EPOLLEXCLUSIVE
epoll flag which avoids duplicate events, on systems that support it.
The patch was tested on a 56 core machine running Linux 4.18 and latest
Open vSwitch. A bridge was created with 2000+ ports, some of them being
veth interfaces with the peer outside the bridge. The latency of the upcall
is measured by setting a single 'action=controller,local' OpenFlow rule to
force all the packets going to the slow path and then to the local port.
A tool[1] injects some packets to the veth outside the bridge, and measures
the delay until the packet is captured on the local port. The rx timestamp
is get from the socket ancillary data in the attribute SO_TIMESTAMPNS, to
avoid having the scheduler delay in the measured time.
The first test measures the average latency for an upcall generated from
a single port. To measure it 100k packets, one every msec, are sent to a
single port and the latencies are measured.
The second test is meant to check latency fairness among ports, namely if
latency is equal between ports or if some ports have lower priority.
The previous test is repeated for every port, the average of the average
latencies and the standard deviation between averages is measured.
The third test serves to measure responsiveness under load. Heavy traffic
is sent through all ports, latency and packet loss is measured
on a single idle port.
The fourth test is all about fairness. Heavy traffic is injected in all
ports but one, latency and packet loss is measured on the single idle port.
This is the test setup:
# nproc
56
# ovs-vsctl show |grep -c Port
2223
# ovs-ofctl dump-flows ovs_upc_br
cookie=0x0, duration=4.827s, table=0, n_packets=0, n_bytes=0, actions=CONTROLLER:65535,LOCAL
# uname -a
Linux fc28 4.18.7-200.fc28.x86_64 #1 SMP Mon Sep 10 15:44:45 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
And these are the results of the tests:
Stock OVS Patched
netlink sockets
in use by vswitchd
lsof -p $(pidof ovs-vswitchd) \
|grep -c GENERIC 91187 2227
Test 1
one port latency
min/avg/max/mdev (us) 2.7/6.6/238.7/1.8 1.6/6.8/160.6/1.7
Test 2
all port
avg latency/mdev (us) 6.51/0.97 6.86/0.17
Test 3
single port latency
under load
avg/mdev (us) 7.5/5.9 3.8/4.8
packet loss 95 % 62 %
Test 4
idle port latency
under load
min/avg/max/mdev (us) 0.8/1.5/210.5/0.9 1.0/2.1/344.5/1.2
packet loss 94 % 4 %
CPU and RAM usage seems not to be affected, the resource usage of vswitchd
idle with 2000+ ports is unchanged:
# ps u $(pidof ovs-vswitchd)
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
openvsw+ 5430 54.3 0.3 4263964 510968 pts/1 RLl+ 16:20 0:50 ovs-vswitchd
[1] https://github.com/teknoraver/network-tools/blob/master/weed.c
Signed-off-by: Matteo Croce <mcroce at redhat.com>
---
lib/dpif-netlink.c | 308 ++++++++++++---------------------------------
1 file changed, 80 insertions(+), 228 deletions(-)
diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
index e6d5a6ec5..79036bf0c 100644
--- a/lib/dpif-netlink.c
+++ b/lib/dpif-netlink.c
@@ -170,7 +170,6 @@ struct dpif_windows_vport_sock {
#endif
struct dpif_handler {
- struct dpif_channel *channels;/* Array of channels for each handler. */
struct epoll_event *epoll_events;
int epoll_fd; /* epoll fd that includes channel socks. */
int n_events; /* Num events returned by epoll_wait(). */
@@ -193,6 +192,7 @@ 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'. */
@@ -331,43 +331,6 @@ open_dpif(const struct dpif_netlink_dp *dp, struct dpif **dpifp)
return 0;
}
-/* Destroys the netlink sockets pointed by the elements in 'socksp'
- * and frees the 'socksp'. */
-static void
-vport_del_socksp__(struct nl_sock **socksp, uint32_t n_socks)
-{
- size_t i;
-
- for (i = 0; i < n_socks; i++) {
- nl_sock_destroy(socksp[i]);
- }
-
- free(socksp);
-}
-
-/* Creates an array of netlink sockets. Returns an array of the
- * corresponding pointers. Records the error in 'error'. */
-static struct nl_sock **
-vport_create_socksp__(uint32_t n_socks, int *error)
-{
- struct nl_sock **socksp = xzalloc(n_socks * sizeof *socksp);
- size_t i;
-
- for (i = 0; i < n_socks; i++) {
- *error = nl_sock_create(NETLINK_GENERIC, &socksp[i]);
- if (*error) {
- goto error;
- }
- }
-
- return socksp;
-
-error:
- vport_del_socksp__(socksp, n_socks);
-
- return NULL;
-}
-
#ifdef _WIN32
static void
vport_delete_sock_pool(struct dpif_handler *handler)
@@ -422,129 +385,34 @@ error:
vport_delete_sock_pool(handler);
return error;
}
-
-/* Returns an array pointers to netlink sockets. The sockets are picked from a
- * pool. Records the error in 'error'. */
-static struct nl_sock **
-vport_create_socksp_windows(struct dpif_netlink *dpif, int *error)
- OVS_REQ_WRLOCK(dpif->upcall_lock)
-{
- uint32_t n_socks = dpif->n_handlers;
- struct nl_sock **socksp;
- size_t i;
-
- ovs_assert(n_socks <= 1);
- socksp = xzalloc(n_socks * sizeof *socksp);
-
- /* Pick netlink sockets to use in a round-robin fashion from each
- * handler's pool of sockets. */
- for (i = 0; i < n_socks; i++) {
- struct dpif_handler *handler = &dpif->handlers[i];
- struct dpif_windows_vport_sock *sock_pool = handler->vport_sock_pool;
- size_t index = handler->last_used_pool_idx;
-
- /* A pool of sockets is allocated when the handler is initialized. */
- if (sock_pool == NULL) {
- free(socksp);
- *error = EINVAL;
- return NULL;
- }
-
- ovs_assert(index < VPORT_SOCK_POOL_SIZE);
- socksp[i] = sock_pool[index].nl_sock;
- socksp[i] = sock_pool[index].nl_sock;
- ovs_assert(socksp[i]);
- index = (index == VPORT_SOCK_POOL_SIZE - 1) ? 0 : index + 1;
- handler->last_used_pool_idx = index;
- }
-
- return socksp;
-}
-
-static void
-vport_del_socksp_windows(struct dpif_netlink *dpif, struct nl_sock **socksp)
-{
- free(socksp);
-}
#endif /* _WIN32 */
-static struct nl_sock **
-vport_create_socksp(struct dpif_netlink *dpif, int *error)
-{
-#ifdef _WIN32
- return vport_create_socksp_windows(dpif, error);
-#else
- return vport_create_socksp__(dpif->n_handlers, error);
-#endif
-}
-
-static void
-vport_del_socksp(struct dpif_netlink *dpif, struct nl_sock **socksp)
-{
-#ifdef _WIN32
- vport_del_socksp_windows(dpif, socksp);
-#else
- vport_del_socksp__(socksp, dpif->n_handlers);
-#endif
-}
-
-/* Given the array of pointers to netlink sockets 'socksp', returns
- * the array of corresponding pids. If the 'socksp' is NULL, returns
- * a single-element array of value 0. */
-static uint32_t *
-vport_socksp_to_pids(struct nl_sock **socksp, uint32_t n_socks)
-{
- uint32_t *pids;
-
- if (!socksp) {
- pids = xzalloc(sizeof *pids);
- } else {
- size_t i;
-
- pids = xzalloc(n_socks * sizeof *pids);
- for (i = 0; i < n_socks; i++) {
- pids[i] = nl_sock_pid(socksp[i]);
- }
- }
-
- return pids;
-}
-
-/* Given the port number 'port_idx', extracts the pids of netlink sockets
- * associated to the port and assigns it to 'upcall_pids'. */
+/* Given the port number 'port_idx', extracts the pid of netlink socket
+ * associated to the port and assigns it to 'upcall_pid'. */
static bool
-vport_get_pids(struct dpif_netlink *dpif, uint32_t port_idx,
- uint32_t **upcall_pids)
+vport_get_pid(struct dpif_netlink *dpif, uint32_t port_idx,
+ uint32_t *upcall_pid)
{
- uint32_t *pids;
- size_t i;
-
/* Since the nl_sock can only be assigned in either all
- * or none "dpif->handlers" channels, the following check
+ * or none "dpif" channels, the following check
* would suffice. */
- if (!dpif->handlers[0].channels[port_idx].sock) {
+ if (!dpif->channels[port_idx].sock) {
return false;
}
ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
- pids = xzalloc(dpif->n_handlers * sizeof *pids);
-
- for (i = 0; i < dpif->n_handlers; i++) {
- pids[i] = nl_sock_pid(dpif->handlers[i].channels[port_idx].sock);
- }
-
- *upcall_pids = pids;
+ *upcall_pid = nl_sock_pid(dpif->channels[port_idx].sock);
return true;
}
static int
-vport_add_channels(struct dpif_netlink *dpif, odp_port_t port_no,
- struct nl_sock **socksp)
+vport_add_channel(struct dpif_netlink *dpif, odp_port_t port_no,
+ struct nl_sock *socksp)
{
struct epoll_event event;
uint32_t port_idx = odp_to_u32(port_no);
- size_t i, j;
+ size_t i;
int error;
if (dpif->handlers == NULL) {
@@ -553,7 +421,7 @@ vport_add_channels(struct dpif_netlink *dpif, odp_port_t port_no,
/* We assume that the datapath densely chooses port numbers, which can
* therefore be used as an index into 'channels' and 'epoll_events' of
- * 'dpif->handler'. */
+ * 'dpif'. */
if (port_idx >= dpif->uc_array_size) {
uint32_t new_size = port_idx + 1;
@@ -563,15 +431,15 @@ vport_add_channels(struct dpif_netlink *dpif, odp_port_t port_no,
return EFBIG;
}
- for (i = 0; i < dpif->n_handlers; i++) {
- struct dpif_handler *handler = &dpif->handlers[i];
+ dpif->channels = xrealloc(dpif->channels,
+ new_size * sizeof *dpif->channels);
- handler->channels = xrealloc(handler->channels,
- new_size * sizeof *handler->channels);
+ for (i = dpif->uc_array_size; i < new_size; i++) {
+ dpif->channels[i].sock = NULL;
+ }
- for (j = dpif->uc_array_size; j < new_size; j++) {
- handler->channels[j].sock = NULL;
- }
+ 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);
@@ -582,32 +450,35 @@ vport_add_channels(struct dpif_netlink *dpif, odp_port_t port_no,
memset(&event, 0, sizeof event);
event.events = EPOLLIN;
+#ifdef EPOLLEXCLUSIVE
+ event.events |= EPOLLEXCLUSIVE;
+#endif
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(socksp[i]),
+ if (epoll_ctl(handler->epoll_fd, EPOLL_CTL_ADD, nl_sock_fd(socksp),
&event) < 0) {
error = errno;
goto error;
}
#endif
- dpif->handlers[i].channels[port_idx].sock = socksp[i];
- dpif->handlers[i].channels[port_idx].last_poll = LLONG_MIN;
}
+ dpif->channels[port_idx].sock = socksp;
+ dpif->channels[port_idx].last_poll = LLONG_MIN;
return 0;
error:
- for (j = 0; j < i; j++) {
#ifndef _WIN32
- epoll_ctl(dpif->handlers[j].epoll_fd, EPOLL_CTL_DEL,
- nl_sock_fd(socksp[j]), NULL);
-#endif
- dpif->handlers[j].channels[port_idx].sock = NULL;
+ while (i--) {
+ epoll_ctl(dpif->handlers[i].epoll_fd, EPOLL_CTL_DEL,
+ nl_sock_fd(socksp), NULL);
}
+#endif
+ dpif->channels[port_idx].sock = NULL;
return error;
}
@@ -618,14 +489,8 @@ vport_del_channels(struct dpif_netlink *dpif, odp_port_t port_no)
uint32_t port_idx = odp_to_u32(port_no);
size_t i;
- if (!dpif->handlers || port_idx >= dpif->uc_array_size) {
- return;
- }
-
- /* Since the sock can only be assigned in either all or none
- * of "dpif->handlers" channels, the following check would
- * suffice. */
- if (!dpif->handlers[0].channels[port_idx].sock) {
+ if (!dpif->handlers || port_idx >= dpif->uc_array_size
+ || !dpif->channels[port_idx].sock) {
return;
}
@@ -633,12 +498,14 @@ vport_del_channels(struct dpif_netlink *dpif, odp_port_t port_no)
struct dpif_handler *handler = &dpif->handlers[i];
#ifndef _WIN32
epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL,
- nl_sock_fd(handler->channels[port_idx].sock), NULL);
- nl_sock_destroy(handler->channels[port_idx].sock);
+ nl_sock_fd(dpif->channels[port_idx].sock), NULL);
#endif
- handler->channels[port_idx].sock = NULL;
handler->event_offset = handler->n_events = 0;
}
+#ifndef _WIN32
+ nl_sock_destroy(dpif->channels[port_idx].sock);
+#endif
+ dpif->channels[port_idx].sock = NULL;
}
static void
@@ -655,10 +522,7 @@ destroy_all_channels(struct dpif_netlink *dpif)
struct dpif_netlink_vport vport_request;
uint32_t upcall_pids = 0;
- /* Since the sock can only be assigned in either all or none
- * of "dpif->handlers" channels, the following check would
- * suffice. */
- if (!dpif->handlers[0].channels[i].sock) {
+ if (!dpif->channels[i].sock) {
continue;
}
@@ -679,11 +543,11 @@ destroy_all_channels(struct dpif_netlink *dpif)
dpif_netlink_handler_uninit(handler);
free(handler->epoll_events);
- free(handler->channels);
}
-
+ free(dpif->channels);
free(dpif->handlers);
dpif->handlers = NULL;
+ dpif->channels = NULL;
dpif->n_handlers = 0;
dpif->uc_array_size = 0;
}
@@ -846,13 +710,12 @@ dpif_netlink_port_add__(struct dpif_netlink *dpif, const char *name,
{
struct dpif_netlink_vport request, reply;
struct ofpbuf *buf;
- struct nl_sock **socksp = NULL;
- uint32_t *upcall_pids;
+ struct nl_sock *socksp = NULL;
+ uint32_t upcall_pids;
int error = 0;
if (dpif->handlers) {
- socksp = vport_create_socksp(dpif, &error);
- if (!socksp) {
+ if (nl_sock_create(NETLINK_GENERIC, &socksp)) {
return error;
}
}
@@ -864,9 +727,9 @@ dpif_netlink_port_add__(struct dpif_netlink *dpif, const char *name,
request.name = name;
request.port_no = *port_nop;
- upcall_pids = vport_socksp_to_pids(socksp, dpif->n_handlers);
- request.n_upcall_pids = socksp ? dpif->n_handlers : 1;
- request.upcall_pids = upcall_pids;
+ upcall_pids = nl_sock_pid(socksp);
+ request.n_upcall_pids = 1;
+ request.upcall_pids = &upcall_pids;
if (options) {
request.options = options->data;
@@ -882,31 +745,27 @@ dpif_netlink_port_add__(struct dpif_netlink *dpif, const char *name,
dpif_name(&dpif->dpif), *port_nop);
}
- vport_del_socksp(dpif, socksp);
+ nl_sock_destroy(socksp);
goto exit;
}
- if (socksp) {
- error = vport_add_channels(dpif, *port_nop, socksp);
- if (error) {
- VLOG_INFO("%s: could not add channel for port %s",
- dpif_name(&dpif->dpif), name);
-
- /* Delete the port. */
- dpif_netlink_vport_init(&request);
- request.cmd = OVS_VPORT_CMD_DEL;
- request.dp_ifindex = dpif->dp_ifindex;
- request.port_no = *port_nop;
- dpif_netlink_vport_transact(&request, NULL, NULL);
- vport_del_socksp(dpif, socksp);
- goto exit;
- }
+ error = vport_add_channel(dpif, *port_nop, socksp);
+ if (error) {
+ VLOG_INFO("%s: could not add channel for port %s",
+ dpif_name(&dpif->dpif), name);
+
+ /* Delete the port. */
+ dpif_netlink_vport_init(&request);
+ request.cmd = OVS_VPORT_CMD_DEL;
+ request.dp_ifindex = dpif->dp_ifindex;
+ request.port_no = *port_nop;
+ dpif_netlink_vport_transact(&request, NULL, NULL);
+ nl_sock_destroy(socksp);
+ goto exit;
}
- free(socksp);
exit:
ofpbuf_delete(buf);
- free(upcall_pids);
return error;
}
@@ -1131,7 +990,7 @@ 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, uint32_t hash)
+ odp_port_t port_no, uint32_t hash OVS_UNUSED)
OVS_REQ_RDLOCK(dpif->upcall_lock)
{
uint32_t port_idx = odp_to_u32(port_no);
@@ -1141,14 +1000,13 @@ dpif_netlink_port_get_pid__(const struct dpif_netlink *dpif,
/* 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;
- struct dpif_handler *h = &dpif->handlers[hash % dpif->n_handlers];
/* 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 (h->channels[idx].sock) {
- pid = nl_sock_pid(h->channels[idx].sock);
+ if (dpif->channels[idx].sock) {
+ pid = nl_sock_pid(dpif->channels[idx].sock);
}
}
@@ -2382,42 +2240,40 @@ dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
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_pids = NULL;
+ uint32_t upcall_pid;
int error;
if (port_no >= dpif->uc_array_size
- || !vport_get_pids(dpif, port_no, &upcall_pids)) {
- struct nl_sock **socksp = vport_create_socksp(dpif, &error);
+ || !vport_get_pid(dpif, port_no, &upcall_pid)) {
+ struct nl_sock *socksp;
- if (!socksp) {
+ if (nl_sock_create(NETLINK_GENERIC, &socksp)) {
goto error;
}
- error = vport_add_channels(dpif, vport.port_no, socksp);
+ error = vport_add_channel(dpif, vport.port_no, socksp);
if (error) {
VLOG_INFO("%s: could not add channels for port %s",
dpif_name(&dpif->dpif), vport.name);
- vport_del_socksp(dpif, socksp);
+ nl_sock_destroy(socksp);
retval = error;
goto error;
}
- upcall_pids = vport_socksp_to_pids(socksp, dpif->n_handlers);
- free(socksp);
+ upcall_pid = nl_sock_pid(socksp);
}
/* Configure the vport to deliver misses to 'sock'. */
if (vport.upcall_pids[0] == 0
- || vport.n_upcall_pids != dpif->n_handlers
- || memcmp(upcall_pids, vport.upcall_pids, n_handlers * sizeof
- *upcall_pids)) {
+ || vport.n_upcall_pids != 1
+ || upcall_pid != vport.upcall_pids[0]) {
struct dpif_netlink_vport vport_request;
dpif_netlink_vport_init(&vport_request);
vport_request.cmd = OVS_VPORT_CMD_SET;
vport_request.dp_ifindex = dpif->dp_ifindex;
vport_request.port_no = vport.port_no;
- vport_request.n_upcall_pids = dpif->n_handlers;
- vport_request.upcall_pids = upcall_pids;
+ vport_request.n_upcall_pids = 1;
+ vport_request.upcall_pids = &upcall_pid;
error = dpif_netlink_vport_transact(&vport_request, NULL, NULL);
if (error) {
VLOG_WARN_RL(&error_rl,
@@ -2438,11 +2294,9 @@ dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
if (port_no < keep_channels_nbits) {
bitmap_set1(keep_channels, port_no);
}
- free(upcall_pids);
continue;
error:
- free(upcall_pids);
vport_del_channels(dpif, vport.port_no);
}
nl_dump_done(&dump);
@@ -2701,7 +2555,7 @@ 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->handlers[handler_id].channels[idx];
+ struct dpif_channel *ch = &dpif->channels[idx];
handler->event_offset++;
@@ -2803,16 +2657,14 @@ dpif_netlink_recv_purge__(struct dpif_netlink *dpif)
OVS_REQ_WRLOCK(dpif->upcall_lock)
{
if (dpif->handlers) {
- size_t i, j;
+ size_t i;
+ if (!dpif->channels[0].sock) {
+ return;
+ }
for (i = 0; i < dpif->uc_array_size; i++ ) {
- if (!dpif->handlers[0].channels[i].sock) {
- continue;
- }
- for (j = 0; j < dpif->n_handlers; j++) {
- nl_sock_drain(dpif->handlers[j].channels[i].sock);
- }
+ nl_sock_drain(dpif->channels[i].sock);
}
}
}
--
2.17.1
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