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netdev-linux: Skip miimon execution when disabled

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When dealing with a large number of ports, one of the performance
bottlenecks is that we loop through all netdevs in the main loop. Miimon
is a contributor to this, checking all devices even if it has never been
enabled.

This patch introduces a counter for the number of netdevs with miimon
configured. If this is 0, then we skip miimon_run() and miimon_wait().
In a test environment of 5000 internal ports and 50 tunnel ports with
bfd, this reduces CPU usage from about 50% to about 45%.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Joe Stringer
2013-11-01 16:34:29 -07:00
committed by Ben Pfaff
parent 7cb279c202
commit 19c8e9c11b
1 changed files with 35 additions and 2 deletions
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37
lib/netdev-linux.c
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@@ -61,6 +61,7 @@
#include "netlink.h"
#include "ofpbuf.h"
#include "openflow/openflow.h"
#include "ovs-atomic.h"
#include "packets.h"
#include "poll-loop.h"
#include "rtnetlink-link.h"
@@ -402,6 +403,11 @@ struct netdev_rx_linux {
* additional log messages. */
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
/* Polling miimon status for all ports causes performance degradation when
* handling a large number of ports. If there are no devices using miimon, then
* we skip netdev_linux_miimon_run() and netdev_linux_miimon_wait(). */
static atomic_int miimon_cnt = ATOMIC_VAR_INIT(0);
static void netdev_linux_run(void);
static int netdev_linux_do_ethtool(const char *name, struct ethtool_cmd *,
@@ -423,6 +429,7 @@ static int set_etheraddr(const char *netdev_name, const uint8_t[ETH_ADDR_LEN]);
static int get_stats_via_netlink(int ifindex, struct netdev_stats *stats);
static int get_stats_via_proc(const char *netdev_name, struct netdev_stats *stats);
static int af_packet_sock(void);
static bool netdev_linux_miimon_enabled(void);
static void netdev_linux_miimon_run(void);
static void netdev_linux_miimon_wait(void);
@@ -485,13 +492,24 @@ netdev_linux_notify_sock(void)
return sock;
}
static bool
netdev_linux_miimon_enabled(void)
{
int miimon;
atomic_read(&miimon_cnt, &miimon);
return miimon > 0;
}
static void
netdev_linux_run(void)
{
struct nl_sock *sock;
int error;
netdev_linux_miimon_run();
if (netdev_linux_miimon_enabled()) {
netdev_linux_miimon_run();
}
sock = netdev_linux_notify_sock();
if (!sock) {
@@ -553,7 +571,9 @@ netdev_linux_wait(void)
{
struct nl_sock *sock;
netdev_linux_miimon_wait();
if (netdev_linux_miimon_enabled()) {
netdev_linux_miimon_wait();
}
sock = netdev_linux_notify_sock();
if (sock) {
nl_sock_wait(sock, POLLIN);
@@ -711,6 +731,11 @@ netdev_linux_destruct(struct netdev *netdev_)
close(netdev->tap_fd);
}
if (netdev->miimon_interval > 0) {
int junk;
atomic_sub(&miimon_cnt, 1, &junk);
}
ovs_mutex_destroy(&netdev->mutex);
}
@@ -1222,6 +1247,14 @@ netdev_linux_set_miimon_interval(struct netdev *netdev_,
ovs_mutex_lock(&netdev->mutex);
interval = interval > 0 ? MAX(interval, 100) : 0;
if (netdev->miimon_interval != interval) {
int junk;
if (interval && !netdev->miimon_interval) {
atomic_add(&miimon_cnt, 1, &junk);
} else if (!interval && netdev->miimon_interval) {
atomic_sub(&miimon_cnt, 1, &junk);
}
netdev->miimon_interval = interval;
timer_set_expired(&netdev->miimon_timer);
}