xenctx_prof.sh

xenctx_prof.sh

#!/bin/bash
#
# xenctx_prof - xenctx based unikernel profiler. Takes a single stack sample.
#
# WARNING: current version is a PROOF OF CONCEPT and is vastly inefficient.
# Check for future work.
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; under version 2 of the License.
# 
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
# 
#  You should have received a copy of the GNU General Public License
#  along with this program; If not, see <http://www.gnu.org/licenses/>.
#
# 26-Jan-2016	Brendan Gregg	Created this.

# Uncommand and edit the following to add a path to xenctx
#PATH=/usr/lib/xen-4.4/bin:$PATH

if ! which xenctx > /dev/null; then
	echo >&2 "ERROR: need xenctx in \$PATH (or edit $0)"
	exit 2
fi
if ! which awk > /dev/null; then
	echo >&2 "ERROR: need awk"
	exit 2
fi

function usage {
	echo >&2 "USAGE: $0 [-s symbol.map] domU_ID"
	exit 1
}

flags=""
while getopts s: opt
do
	case $opt in
	s)	flags="$flags -s $OPTARG" ;;
	h|?)	usage ;;
	esac
done
shift $(( $OPTIND - 1 ))
(( $# < 1 )) && usage
dom=$1

xenctx -C $flags $dom | awk '
	# parse output of xenctx. sample output lines inline.

	# rbp: 000000000019fe50	 r8: 000000000000000d	 r9: 000000000000000d
	$1 == "rbp:" { rbp = $2 ":" }

	# 000000000019feb0:   [<0000000000000000>] .comment
	instack && $2 ~ /\[<0000000000000000>\]/ { exit }

	# 000000000019fe50:   [<000000000019fe70>] stack+0x1be30
	# 000000000019fe58:   [<0000000000007312>] camlUnikernel____pa_lwt_loop_1376+0x72
	# ...
	instack {
		addr = sub(/:/, "", $1)
		if ($NF !~ /0x..../) {
			print $NF
		} else {
			# offset suspiciously large (probably wrong symbol); print hex instead
			addr = $2; gsub(/[\[\]<>]/, "", addr); print "0x" addr
		}
	}

	#                    [<0000000000049ad7>] camlLwt__return_1319+0x27 <--
	$NF == "<--" { print $(NF - 1); instack = 1 }
'