This patch enhances dpif-netdev-perf to detect iterations with
suspicious statistics according to the following criteria:
- iteration lasts longer than US_THR microseconds (default 250).
This can be used to capture events where a PMD is blocked or
interrupted for such a period of time that there is a risk for
dropped packets on any of its Rx queues.
- max vhost qlen exceeds a threshold Q_THR (default 128). This can
be used to infer virtio queue overruns and dropped packets inside
a VM, which are not visible in OVS otherwise.
Such suspicious iterations can be logged together with their iteration
statistics to be able to correlate them to packet drop or other events
outside OVS.
A new command is introduced to enable/disable logging at run-time and
to adjust the above thresholds for suspicious iterations:
ovs-appctl dpif-netdev/pmd-perf-log-set on | off
[-b before] [-a after] [-us usec] [-q qlen]
Turn logging on or off at run-time (on|off).
-b before: The number of iterations before the suspicious iteration to
be logged (default 5).
-a after: The number of iterations after the suspicious iteration to
be logged (default 5).
-q qlen: Suspicious vhost queue fill level threshold. Increase this
to 512 if the Qemu supports 1024 virtio queue length.
(default 128).
-us usec: change the duration threshold for a suspicious iteration
(default 250 us).
If more than 100 iterations before or after a suspicious iteration have
been looged once, OVS falls back to the safe default values (5/5) to
avoid that logging itself causes continuos further logging.
Signed-off-by: Jan Scheurich <[email protected]>
---
NEWS | 2 +
lib/dpif-netdev-perf.c | 142 ++++++++++++++++++++++++++++++++++++++++++++
lib/dpif-netdev-perf.h | 40 ++++++++++++-
lib/dpif-netdev.c | 7 ++-
lib/netdev-dpif-unixctl.man | 47 ++++++++++++++-
5 files changed, 233 insertions(+), 5 deletions(-)
diff --git a/NEWS b/NEWS
index 743528e..7d40374 100644
--- a/NEWS
+++ b/NEWS
@@ -47,6 +47,8 @@ Post-v2.8.0
* Commands ovs-appctl dpif-netdev/pmd-*-show can now work on a single PMD
* Detailed PMD performance metrics available with new command
ovs-appctl dpif-netdev/pmd-perf-show
+ * Supervision of PMD performance metrics and logging of suspicious
+ iterations
- vswitchd:
* Datapath IDs may now be specified as 0x1 (etc.) instead of 16 digits.
* Configuring a controller, or unconfiguring all controllers, now deletes
diff --git a/lib/dpif-netdev-perf.c b/lib/dpif-netdev-perf.c
index e0ef15d..259a6c8 100644
--- a/lib/dpif-netdev-perf.c
+++ b/lib/dpif-netdev-perf.c
@@ -24,6 +24,23 @@
VLOG_DEFINE_THIS_MODULE(pmd_perf);
+#define ITER_US_THRESHOLD 250 /* Warning threshold for iteration duration
+ in microseconds. */
+#define VHOST_QUEUE_FULL 128 /* Size of the virtio TX queue. */
+#define LOG_IT_BEFORE 5 /* Number of iteration to log before
+ suspicious iteration. */
+#define LOG_IT_AFTER 5 /* Number of iteration to log after
+ suspicious iteration. */
+
+bool log_on = false;
+static uint32_t log_it_before = LOG_IT_BEFORE;
+static uint32_t log_it_after = LOG_IT_AFTER;
+static uint32_t log_us_thr = ITER_US_THRESHOLD;
+uint32_t log_q_thr = VHOST_QUEUE_FULL;
+uint64_t iter_cycle_threshold;
+
+static struct vlog_rate_limit latency_rl = VLOG_RATE_LIMIT_INIT(600, 600);
+
#ifdef DPDK_NETDEV
static uint64_t
get_tsc_hz(void)
@@ -124,6 +141,8 @@ pmd_perf_stats_init(struct pmd_perf_stats *s)
histogram_walls_set_log(&s->cycles_per_upcall, 1000, 1000000);
histogram_walls_set_log(&s->max_vhost_qfill, 0, 512);
s->start_ms = time_msec();
+ s->log_begin_it = UINT64_MAX;
+ s->log_end_it = UINT64_MAX;
}
void
@@ -362,6 +381,8 @@ pmd_perf_stats_clear__(struct pmd_perf_stats *s)
history_init(&s->milliseconds);
s->start_ms = time_msec();
s->milliseconds.sample[0].timestamp = s->start_ms;
+ s->log_begin_it = UINT64_MAX;
+ s->log_end_it = UINT64_MAX;
/* Clearing finished. */
s->clear = false;
}
@@ -387,3 +408,124 @@ non_pmd_perf_stats_clear(struct pmd_perf_stats *s)
{
pmd_perf_stats_clear__(s);
}
+
+void
+pmd_perf_log_suspicious_iteration(struct pmd_perf_stats *s,
+ uint64_t cycles,
+ char *reason)
+{
+ VLOG_WARN_RL(&latency_rl,
+ "Suspicious iteration (%s): tsc=%"PRIu64
+ " duration=%"PRIu64" us\n",
+ reason, s->current.timestamp,
+ (1000000L * cycles) / get_tsc_hz());
+ if (log_it_before + log_it_after > 0) {
+ if (s->log_begin_it == UINT64_MAX) {
+ s->log_begin_it =
+ (s->iterations.idx + HISTORY_LEN - log_it_before)
+ % HISTORY_LEN;
+ }
+ s->log_end_it =
+ (s->iterations.idx + log_it_after) % HISTORY_LEN;
+ }
+}
+
+void
+pmd_perf_log_iteration_neighborhood(struct pmd_perf_stats *s)
+{
+ struct ds log = DS_EMPTY_INITIALIZER;
+ pmd_perf_format_iteration_history(&log, s,
+ (s->log_end_it + HISTORY_LEN - s->log_begin_it) % HISTORY_LEN);
+ VLOG_WARN_RL(&latency_rl,
+ "Neighborhood of suspicious iteration:\n"
+ "%s", ds_cstr(&log));
+ ds_destroy(&log);
+ s->log_end_it = s->log_begin_it = UINT64_MAX;
+ if (log_it_before > 100 || log_it_after > 100) {
+ /* Reset to safe default values to avoid disturbance. */
+ log_it_before = LOG_IT_BEFORE;
+ log_it_after = LOG_IT_AFTER;
+ }
+}
+
+void
+pmd_perf_log_set_cmd(struct unixctl_conn *conn,
+ int argc, const char *argv[],
+ void *aux OVS_UNUSED)
+{
+ int it_before, it_after, us_thr, q_thr;
+ bool on;
+ bool usage = false;
+
+ on = log_on;
+ it_before = log_it_before;
+ it_after = log_it_after;
+ q_thr = log_q_thr;
+ us_thr = log_us_thr;
+
+ while (argc > 1) {
+ if (!strcmp(argv[1], "on")) {
+ on = true;
+ argc--;
+ argv++;
+ } else if (!strcmp(argv[1], "off")) {
+ on = false;
+ argc--;
+ argv++;
+ } else if (!strcmp(argv[1], "-a")) {
+ it_after = strtol(argv[2], NULL, 10);
+ if (it_after < 0) {
+ it_after = 0;
+ } else if (it_before + it_after > HISTORY_LEN-1) {
+ it_after = HISTORY_LEN-1 - it_before;
+ }
+ argc -= 2;
+ argv += 2;
+ } else if (!strcmp(argv[1], "-b")) {
+ it_before = strtol(argv[2], NULL, 10);
+ if (it_before < 0) {
+ it_before = 0;
+ } else if (it_before > HISTORY_LEN-10) {
+ it_before = HISTORY_LEN-10;
+ }
+ argc -= 2;
+ argv += 2;
+ } else if (!strcmp(argv[1], "-q")) {
+ q_thr = strtol(argv[2], NULL, 10);
+ if (q_thr < 0) {
+ q_thr = 0;
+ }
+ argc -= 2;
+ argv += 2;
+ } else if (!strcmp(argv[1], "-us")) {
+ us_thr = strtol(argv[2], NULL, 10);
+ if (us_thr < 0) {
+ us_thr = 0;
+ }
+ argc -= 2;
+ argv += 2;
+ } else {
+ usage = true;
+ break;
+ }
+ }
+
+ if (usage) {
+ unixctl_command_reply_error(conn,
+ "Usage: ovs-appctl dpif-netdev/pmd-perf-log-set "
+ "[on|off] [-b before] [-a after] [-us usec] [-q qlen]");
+ return;
+ }
+
+ VLOG_INFO("pmd-perf-log-set: %s, before=%d, after=%d, us_thr=%d,"
+ " q_thr=%d\n",
+ on ? "on" : "off", it_before, it_after, us_thr, q_thr);
+ log_on = on;
+ log_it_before = it_before;
+ log_it_after = it_after;
+ log_q_thr = q_thr;
+ log_us_thr = us_thr;
+ iter_cycle_threshold = (log_us_thr * get_tsc_hz()) / 1000000L;
+
+ unixctl_command_reply(conn, "");
+}
diff --git a/lib/dpif-netdev-perf.h b/lib/dpif-netdev-perf.h
index 7a89c40..aa55c68 100644
--- a/lib/dpif-netdev-perf.h
+++ b/lib/dpif-netdev-perf.h
@@ -160,8 +160,12 @@ struct pmd_perf_stats {
struct histogram max_vhost_qfill;
/* Iteration history buffer. */
struct history iterations;
- /* Millisecond hitory buffer. */
+ /* Millisecond history buffer. */
struct history milliseconds;
+ /* Start of iteration range to log. */
+ uint64_t log_begin_it;
+ /* End of iteration range to log. */
+ uint64_t log_end_it;
};
/* Support for accurate timing of PMD execution on TSC clock cycle level.
@@ -322,6 +326,17 @@ history_store(struct history *h, struct iter_stats *is)
return history_next(h);
}
+/* Data and function related to logging of suspicious iterations. */
+
+extern bool log_on;
+extern uint32_t log_q_thr;
+extern uint64_t iter_cycle_threshold;
+
+void pmd_perf_log_suspicious_iteration(struct pmd_perf_stats *s,
+ uint64_t cycles,
+ char *reason);
+void pmd_perf_log_iteration_neighborhood(struct pmd_perf_stats *s);
+
/* Functions recording PMD metrics per iteration. */
static inline void
@@ -351,6 +366,7 @@ pmd_perf_end_iteration(struct pmd_perf_stats *s, int
rx_packets,
uint64_t now_tsc = cycles_counter_update(s);
struct iter_stats *cum_ms;
uint64_t cycles, cycles_per_pkt = 0;
+ char *reason = NULL;
if (OVS_UNLIKELY(s->current.timestamp == 0)) {
/* Stats were cleared during the ongoing iteration. */
@@ -404,6 +420,23 @@ pmd_perf_end_iteration(struct pmd_perf_stats *s, int
rx_packets,
cum_ms->batches += s->current.batches;
cum_ms->max_vhost_qfill += s->current.max_vhost_qfill;
+ if (log_on) {
+ /* Log suspicious iterations. */
+ if (cycles > iter_cycle_threshold) {
+ reason = "Excessive total cycles";
+ } else if (s->current.max_vhost_qfill >= log_q_thr) {
+ reason = "Vhost RX queue full";
+ }
+ if (OVS_UNLIKELY(reason)) {
+ pmd_perf_log_suspicious_iteration(s, cycles, reason);
+ }
+
+ /* Log iteration stats interval when required. */
+ if (OVS_UNLIKELY(s->log_end_it == s->iterations.idx)) {
+ pmd_perf_log_iteration_neighborhood(s);
+ }
+ }
+
/* Store in iteration history. */
history_store(&s->iterations, &s->current);
if (now_tsc > s->next_check_tsc) {
@@ -426,7 +459,7 @@ pmd_perf_end_iteration(struct pmd_perf_stats *s, int
rx_packets,
}
}
-/* Functions for formatting the output of commands. */
+/* Formatting the output of commands. */
struct pmd_perf_params {
int command_type;
@@ -443,6 +476,9 @@ void pmd_perf_format_iteration_history(struct ds *str,
int n_iter);
void pmd_perf_format_ms_history(struct ds *str, struct pmd_perf_stats *s,
int n_ms);
+void pmd_perf_log_set_cmd(struct unixctl_conn *conn,
+ int argc, const char *argv[],
+ void *aux OVS_UNUSED);
#ifdef __cplusplus
}
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index f5931bf..b493216 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -1095,7 +1095,7 @@ dpif_netdev_pmd_info(struct unixctl_conn *conn, int argc,
const char *argv[],
ovs_mutex_lock(&dp_netdev_mutex);
while (argc > 1) {
- if (!strcmp(argv[1], "-pmd") && argc >= 3) {
+ if (!strcmp(argv[1], "-pmd") && argc > 2) {
if (str_to_uint(argv[2], 10, &core_id)) {
filter_on_pmd = true;
}
@@ -1218,6 +1218,11 @@ dpif_netdev_init(void)
unixctl_command_register("dpif-netdev/pmd-rxq-rebalance", "[dp]",
0, 1, dpif_netdev_pmd_rebalance,
NULL);
+ unixctl_command_register("dpif-netdev/pmd-perf-log-set",
+ "on|off [-b before] [-a after] "
+ "[-us usec] [-q qlen]",
+ 0, 10, pmd_perf_log_set_cmd,
+ NULL);
return 0;
}
diff --git a/lib/netdev-dpif-unixctl.man b/lib/netdev-dpif-unixctl.man
index 53f4c51..82e372f 100644
--- a/lib/netdev-dpif-unixctl.man
+++ b/lib/netdev-dpif-unixctl.man
@@ -70,7 +70,7 @@ This raw recorded data is used threefold:
The command options are
- \fB-nh\fR: Suppress the histograms
+ \fB-nh\fR: Suppress the histograms
\fB-it\fR \fIiter_len\fR: Display the last iter_len iteration stats
\fB-ms\fR \fIms_len\fR: Display the last ms_len millisecond stats
@@ -101,10 +101,53 @@ To reset the counters and start a new measurement use
.
.IP "\fBdpif-netdev/pmd-stats-clear\fR [\fIdp\fR]"
Resets to zero the per pmd thread performance numbers shown by the
-\fBdpif-netdev/pmd-stats-show\fR and \Bdpif-netdev/pmd-perf-show \fR commands.
+\fBdpif-netdev/pmd-stats-show\fR and \fBdpif-netdev/pmd-perf-show\fR commands.
It will NOT reset datapath or bridge statistics, only the values shown by
the above commands.
.
+.IP "\fBdpif-netdev/pmd-perf-log-set\fR \fBon\fR|\fBoff\fR \
+ [\fB-b\fR \fIbefore\fR] [\fB-a\fR \fIafter\fR] [\fB-us\fR \fIusec\fR] \
+ [\fB-q\fR \fIqlen\fR]"
+.
+The userspace "netdev" datapath is able to supervise the PMD performance
+metrics and detect iterations with suspicious statistics according to the
+following criteria:
+
+- The iteration lasts longer than \fIusec\fR microseconds (default 250).
+ This can be used to capture events where a PMD is blocked or
+ interrupted for such a period of time that there is a risk for
+ dropped packets on any of its Rx queues.
+
+- The max vhost qlen exceeds a threshold \fIqlen\fR (default 128). This can
+ be used to infer virtio queue overruns and dropped packets inside a VM,
+ which are not visible in OVS otherwise.
+
+Such suspicious iterations can be logged together with their iteration
+statistics in the \fBovs-vswitchd.log\fR to be able to correlate them to
+packet drop or other events outside OVS.
+
+The above command enables (\fBon\fR) or disables (\fBoff\fR) supervision and
+logging at run-time and can be used to adjust the above thresholds for
+detecting suspicious iterations. By default supervision and logging is
+disabled.
+
+The command options are:
+
+ \fB-b\fR \fIbefore\fR:
+ The number of iterations before the suspicious iteration to be logged
(default 5).
+ \fB-a\fR \fIafter\fR:
+ The number of iterations after the suspicious iteration to be logged
(default 5).
+ \fB-q\fR \fIqlen\fR:
+ Suspicious vhost queue fill level threshold. Increase this to 512 if
+ the Qemu supports 1024 virtio queue length (default 128).
+ \fB-us\fR \fIusec\fR:
+ change the duration threshold for a suspicious iteration (default 250
us).
+
+If more than 100 iterations before or after a suspicious iteration have
+been looged once, OVS falls back to the safe default values (5/5) to
+avoid that logging itself causes continuos further suspicious iterations
+and continuous logging.
+.
.IP "\fBdpif-netdev/pmd-rxq-show\fR [\fB-pmd\fR \fIcore\fR] [\fIdp\fR]"
For one or all pmd threads of the datapath \fIdp\fR show the list of queue-ids
with port names, which this thread polls.
--
1.9.1
_______________________________________________
dev mailing list
[email protected]
https://mail.openvswitch.org/mailman/listinfo/ovs-dev
