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https://github.com/openvswitch/ovs
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dpif-netdev: Add dpif-netdev/pmd-stats-* appctl commands.
These commands can be used to get packets and cycles counters on a pmd thread basis. They're useful to get a clearer picture about the performance of the userspace datapath. They export these pieces of information: - A (per-thread) view of the caches hit rate. Hits in the exact match cache are reported separately from hits in the masked classifier - A rough cycles count. This will allow to estimate the load of OVS and the polling overhead. Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com> Acked-by: Ethan Jackson <ethan@nicira.com>
This commit is contained in:
Daniele Di Proietto
committed by
Ethan Jackson
Ethan Jackson
parent
c8973eb634
commit
6553d06bd1
@@ -409,6 +409,13 @@ struct dp_netdev_pmd_thread {
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/* threads on same numa node. */
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int core_id; /* CPU core id of this pmd thread. */
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int numa_id; /* numa node id of this pmd thread. */
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/* Only a pmd thread can write on its own 'cycles' and 'stats'.
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* The main thread keeps 'stats_zero' and 'cycles_zero' as base
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* values and subtracts them from 'stats' and 'cycles' before
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* reporting to the user */
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unsigned long long stats_zero[DP_N_STATS];
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uint64_t cycles_zero[PMD_N_CYCLES];
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};
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#define PMD_INITIAL_SEQ 1
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@@ -516,6 +523,182 @@ get_dp_netdev(const struct dpif *dpif)
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{
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return dpif_netdev_cast(dpif)->dp;
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}
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enum pmd_info_type {
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PMD_INFO_SHOW_STATS, /* show how cpu cycles are spent */
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PMD_INFO_CLEAR_STATS /* set the cycles count to 0 */
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};
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static void
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pmd_info_show_stats(struct ds *reply,
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struct dp_netdev_pmd_thread *pmd,
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unsigned long long stats[DP_N_STATS],
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uint64_t cycles[PMD_N_CYCLES])
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{
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unsigned long long total_packets = 0;
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uint64_t total_cycles = 0;
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int i;
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/* These loops subtracts reference values ('*_zero') from the counters.
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* Since loads and stores are relaxed, it might be possible for a '*_zero'
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* value to be more recent than the current value we're reading from the
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* counter. This is not a big problem, since these numbers are not
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* supposed to be too accurate, but we should at least make sure that
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* the result is not negative. */
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for (i = 0; i < DP_N_STATS; i++) {
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if (stats[i] > pmd->stats_zero[i]) {
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stats[i] -= pmd->stats_zero[i];
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} else {
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stats[i] = 0;
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}
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if (i != DP_STAT_LOST) {
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/* Lost packets are already included in DP_STAT_MISS */
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total_packets += stats[i];
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}
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}
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for (i = 0; i < PMD_N_CYCLES; i++) {
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if (cycles[i] > pmd->cycles_zero[i]) {
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cycles[i] -= pmd->cycles_zero[i];
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} else {
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cycles[i] = 0;
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}
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total_cycles += cycles[i];
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}
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ds_put_cstr(reply, (pmd->core_id == NON_PMD_CORE_ID)
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? "main thread" : "pmd thread");
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if (pmd->numa_id != OVS_NUMA_UNSPEC) {
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ds_put_format(reply, " numa_id %d", pmd->numa_id);
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}
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if (pmd->core_id != OVS_CORE_UNSPEC) {
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ds_put_format(reply, " core_id %d", pmd->core_id);
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}
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ds_put_cstr(reply, ":\n");
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ds_put_format(reply,
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"\temc hits:%llu\n\tmegaflow hits:%llu\n"
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"\tmiss:%llu\n\tlost:%llu\n",
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stats[DP_STAT_EXACT_HIT], stats[DP_STAT_MASKED_HIT],
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stats[DP_STAT_MISS], stats[DP_STAT_LOST]);
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if (total_cycles == 0) {
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return;
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}
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ds_put_format(reply,
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"\tpolling cycles:%"PRIu64" (%.02f%%)\n"
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"\tprocessing cycles:%"PRIu64" (%.02f%%)\n",
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cycles[PMD_CYCLES_POLLING],
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cycles[PMD_CYCLES_POLLING] / (double)total_cycles * 100,
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cycles[PMD_CYCLES_PROCESSING],
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cycles[PMD_CYCLES_PROCESSING] / (double)total_cycles * 100);
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if (total_packets == 0) {
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return;
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}
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ds_put_format(reply,
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"\tavg cycles per packet: %.02f (%"PRIu64"/%llu)\n",
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total_cycles / (double)total_packets,
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total_cycles, total_packets);
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ds_put_format(reply,
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"\tavg processing cycles per packet: "
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"%.02f (%"PRIu64"/%llu)\n",
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cycles[PMD_CYCLES_PROCESSING] / (double)total_packets,
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cycles[PMD_CYCLES_PROCESSING], total_packets);
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}
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static void
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pmd_info_clear_stats(struct ds *reply OVS_UNUSED,
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struct dp_netdev_pmd_thread *pmd,
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unsigned long long stats[DP_N_STATS],
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uint64_t cycles[PMD_N_CYCLES])
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{
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int i;
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/* We cannot write 'stats' and 'cycles' (because they're written by other
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* threads) and we shouldn't change 'stats' (because they're used to count
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* datapath stats, which must not be cleared here). Instead, we save the
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* current values and subtract them from the values to be displayed in the
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* future */
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for (i = 0; i < DP_N_STATS; i++) {
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pmd->stats_zero[i] = stats[i];
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}
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for (i = 0; i < PMD_N_CYCLES; i++) {
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pmd->cycles_zero[i] = cycles[i];
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}
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}
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static void
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dpif_netdev_pmd_info(struct unixctl_conn *conn, int argc, const char *argv[],
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void *aux)
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{
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struct ds reply = DS_EMPTY_INITIALIZER;
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struct dp_netdev_pmd_thread *pmd;
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struct dp_netdev *dp = NULL;
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enum pmd_info_type type = *(enum pmd_info_type *) aux;
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ovs_mutex_lock(&dp_netdev_mutex);
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if (argc == 2) {
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dp = shash_find_data(&dp_netdevs, argv[1]);
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} else if (shash_count(&dp_netdevs) == 1) {
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/* There's only one datapath */
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dp = shash_first(&dp_netdevs)->data;
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}
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if (!dp) {
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ovs_mutex_unlock(&dp_netdev_mutex);
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unixctl_command_reply_error(conn,
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"please specify an existing datapath");
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return;
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}
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CMAP_FOR_EACH (pmd, node, &dp->poll_threads) {
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unsigned long long stats[DP_N_STATS];
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uint64_t cycles[PMD_N_CYCLES];
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int i;
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/* Read current stats and cycle counters */
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for (i = 0; i < ARRAY_SIZE(stats); i++) {
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atomic_read_relaxed(&pmd->stats.n[i], &stats[i]);
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}
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for (i = 0; i < ARRAY_SIZE(cycles); i++) {
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atomic_read_relaxed(&pmd->cycles.n[i], &cycles[i]);
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}
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if (type == PMD_INFO_CLEAR_STATS) {
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pmd_info_clear_stats(&reply, pmd, stats, cycles);
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} else if (type == PMD_INFO_SHOW_STATS) {
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pmd_info_show_stats(&reply, pmd, stats, cycles);
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}
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}
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ovs_mutex_unlock(&dp_netdev_mutex);
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unixctl_command_reply(conn, ds_cstr(&reply));
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ds_destroy(&reply);
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}
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static int
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dpif_netdev_init(void)
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{
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static enum pmd_info_type show_aux = PMD_INFO_SHOW_STATS,
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clear_aux = PMD_INFO_CLEAR_STATS;
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unixctl_command_register("dpif-netdev/pmd-stats-show", "[dp]",
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0, 1, dpif_netdev_pmd_info,
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(void *)&show_aux);
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unixctl_command_register("dpif-netdev/pmd-stats-clear", "[dp]",
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0, 1, dpif_netdev_pmd_info,
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(void *)&clear_aux);
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return 0;
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}
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static int
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dpif_netdev_enumerate(struct sset *all_dps,
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@@ -3353,7 +3536,7 @@ dp_netdev_execute_actions(struct dp_netdev_pmd_thread *pmd,
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const struct dpif_class dpif_netdev_class = {
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"netdev",
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NULL, /* init */
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dpif_netdev_init,
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dpif_netdev_enumerate,
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dpif_netdev_port_open_type,
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dpif_netdev_open,
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