debug/io-stats: Add FOP sampling feature

Summary:
- Using sampling feature you can record details about every Nth FOP.
  The fields in each sample are: FOP type, hostname, uid, gid, FOP priority,
  port and time taken (latency) to fufill the request.
- Implemented using a ring buffer which is not (m/c) allocated in the IO path,
  this should make the sampling process pretty cheap.
- DNS resolution done @ dump time not @ sample time for performance w/
  cache
- Metrics can be used for both diagnostics, traffic/IO profiling as well
  as P95/P99 calculations
- To control this feature there are two new volume options:
  diagnostics.fop-sample-interval - The sampling interval, e.g. 1 means
  sample every FOP, 100 means sample every 100th FOP
  diagnostics.fop-sample-buf-size - The size (in bytes) of the ring
  buffer used to store the samples.  In the even more samples
  are collected in the stats dump interval than can be held in this buffer,
  the oldest samples shall be discarded.  Samples are stored in the log
  directory under /var/log/glusterfs/samples.
- Uses DNS cache written by sshreyas@fb.com (Thank-you!), the DNS cache
  TTL is controlled by the diagnostics.stats-dnscache-ttl-sec option
  and defaults to 24hrs.

Test Plan:
- Valgrind'd to ensure it's leak free
- Run prove test(s)
- Shadow testing on 100+ brick cluster

Change-Id: I9ee14c2fa18486b7efb38e59f70687249d3f96d8
BUG: 1271310
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-on: http://review.gluster.org/12210
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/tests/basic/fop-sampling.t b/tests/basic/fop-sampling.t
new file mode 100644
index 00000000000..cea8aa737c0
--- /dev/null
+++ b/tests/basic/fop-sampling.t
@@ -0,0 +1,61 @@
+#!/bin/bash
+#
+
+. $(dirname $0)/../include.rc
+. $(dirname $0)/../volume.rc
+
+SAMPLE_FILE="$(gluster --print-logdir)/samples/glusterfs_${V0}.samp"
+
+function print_cnt() {
+  local FOP_TYPE=$1
+  local FOP_CNT=$(grep ,${FOP_TYPE} ${SAMPLE_FILE} | wc -l)
+  echo $FOP_CNT
+}
+
+# Verify we got non-zero counts for stats/lookup/readdir
+check_samples() {
+        STAT_CNT=$(print_cnt STAT)
+        if [ "$STAT_CNT" -le "0" ]; then
+                echo "STAT count is zero"
+                return
+        fi
+
+        LOOKUP_CNT=$(print_cnt LOOKUP)
+        if [ "$LOOKUP_CNT" -le "0" ]; then
+                echo "LOOKUP count is zero"
+                return
+        fi
+
+        READDIR_CNT=$(print_cnt READDIR)
+        if [ "$READDIR_CNT" -le "0" ]; then
+                echo "READDIR count is zero"
+                return
+        fi
+
+        echo "OK"
+}
+
+cleanup;
+TEST glusterd
+TEST pidof glusterd
+TEST $CLI volume create $V0 replica 3 $H0:$B0/${V0}{0,1,2}
+TEST $CLI volume set $V0 nfs.disable off
+TEST $CLI volume set $V0 diagnostics.latency-measurement on
+TEST $CLI volume set $V0 diagnostics.count-fop-hits on
+TEST $CLI volume set $V0 diagnostics.stats-dump-interval 2
+TEST $CLI volume set $V0 diagnostics.fop-sample-buf-size 65535
+TEST $CLI volume set $V0 diagnostics.fop-sample-interval 1
+TEST $CLI volume set $V0 diagnostics.stats-dnscache-ttl-sec 3600
+
+TEST $CLI volume start $V0
+TEST glusterfs --volfile-id=/$V0 --volfile-server=$H0 $M0 --attribute-timeout=0 --entry-timeout=0
+
+for i in {1..5}
+do
+        dd if=/dev/zero of=${M0}/testfile$i bs=4k count=1
+done
+
+TEST ls -l $M0
+EXPECT_WITHIN 6 "OK" check_samples
+
+cleanup