From a83e90b56080d1c86f98e66d146f781c19d150c5 Mon Sep 17 00:00:00 2001
From: Tim Buckley <timothy.jas.buckley@hp.com>
Date: Wed, 5 Aug 2015 10:25:00 -0600
Subject: [PATCH] Enable CSV logging output for DStat.

Future work toward visualization of DevStack and devstack-gate performance
would benefit greatly from the availability of machine-parsable DStat output.
This patch outputs an additional logfile to $LOGDIR, `dstat-csv.log`, using
DStat's built-in CSV logging functionality.

An additional instance of DStat is started during start_dstat that outputs
to CSV-formatted text without `--top-cpu-adv` and `-top-io-adv` enabled, as
these plugins are currently incompatible with CSV output. To facilitate this,
a new `dstat.sh` script is added to $TOP_DIR/tools/ to act as a daemon to
manage the two processes.

Change-Id: I826c94c35b6a109308b4f132c181ff7a1f63bc7b
Depends-On: I534fb1f9356a7948d2fec0aecc7f275e47362a11
---
 lib/dstat      |  3 +--
 tools/dstat.sh | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100755 tools/dstat.sh

diff --git a/lib/dstat b/lib/dstat
index f11bfa55c0..fe4790b12d 100644
--- a/lib/dstat
+++ b/lib/dstat
@@ -19,8 +19,7 @@ set +o xtrace
 # start_dstat() - Start running processes, including screen
 function start_dstat {
     # A better kind of sysstat, with the top process per time slice
-    DSTAT_OPTS="-tcmndrylpg --top-cpu-adv --top-io-adv"
-    run_process dstat "dstat $DSTAT_OPTS"
+    run_process dstat "$TOP_DIR/tools/dstat.sh $LOGDIR"
 
     # To enable peakmem_tracker add:
     #    enable_service peakmem_tracker
diff --git a/tools/dstat.sh b/tools/dstat.sh
new file mode 100755
index 0000000000..6ba4515acf
--- /dev/null
+++ b/tools/dstat.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# **tools/dstat.sh** - Execute instances of DStat to log system load info
+#
+# Multiple instances of DStat are executed in order to take advantage of
+# incompatible features, particularly CSV output and the "top-cpu-adv" and
+# "top-io-adv" flags.
+#
+# Assumes:
+#  - dstat command is installed
+
+# Retreive log directory as argument from calling script.
+LOGDIR=$1
+
+# Command line arguments for primary DStat process.
+DSTAT_OPTS="-tcmndrylpg --top-cpu-adv --top-io-adv"
+
+# Command-line arguments for secondary background DStat process.
+DSTAT_CSV_OPTS="-tcmndrylpg --output $LOGDIR/dstat-csv.log"
+
+# Execute and background the secondary dstat process and discard its output.
+dstat $DSTAT_CSV_OPTS >& /dev/null &
+
+# Execute and background the primary dstat process, but keep its output in this
+# TTY.
+dstat $DSTAT_OPTS &
+
+# Catch any exit signals, making sure to also terminate any child processes.
+trap "kill -- -$$" EXIT
+
+# Keep this script running as long as child dstat processes are alive.
+wait