xref: /freebsd/cddl/usr.sbin/dwatch/libexec/dtmalloc (revision 434283fda99e89af20c3fe95fde427624ae96d04)

# -*- tab-width: 4 -*- ;; Emacs
# vi: set filetype=sh tabstop=8 shiftwidth=8 noexpandtab :: Vi/ViM
############################################################ IDENT(1)
#
# $Title: dwatch(8) module for malloc(9) type activity $
# $Copyright: 2026 Devin Teske. All rights reserved. $
#
############################################################ DESCRIPTION
#
# Print kernel malloc(9) and free(9) activity by malloc type, via the
# dtmalloc provider (one malloc and one free probe per type; see
# vmstat -m for the types). The default profile prints allocations and
# frees meeting a size threshold (default 65536 bytes; tunable via
# DWATCH_MALLOC_MIN in the environment, 0 to show everything),
# answering "who is allocating huge kernel buffers?" Use
# dtmalloc-NAME to watch a single type (e.g., dtmalloc-devbuf).
# The dtmalloc-top profile maintains a running catalog, updated every
# 3 seconds, of net bytes and outstanding allocation balance by type:
# a type whose net bytes climb without bound while the system is in
# steady state is a leak suspect. NB: the catalog reflects activity
# since the watch began, not preexisting allocations, and caches
# legitimately hold what they allocate.
#
############################################################ PRAGMAS

case "$PROFILE" in
dtmalloc-top)
	DTRACE_PRAGMA="
		option quiet
		option aggsortrev
	" # END-QUOTE
	;;
esac

############################################################ PROBE

case "$PROFILE" in
dtmalloc)
	: ${PROBE:=dtmalloc:::malloc, dtmalloc:::free} ;;
dtmalloc-top)
	: ${PROBE:=profile:::tick-3s} ;;
*)
	: ${PROBE:=$( echo \
		dtmalloc::${PROFILE#dtmalloc-}:malloc, \
		dtmalloc::${PROFILE#dtmalloc-}:free )} ;;
esac

############################################################ EVENT ACTION

: ${DWATCH_MALLOC_MIN:=65536}

case "$DWATCH_MALLOC_MIN" in
""|*[!0-9]*) die "DWATCH_MALLOC_MIN must be a number" ;; # NOTREACHED
esac

[ "$CUSTOM_TEST" ] || case "$PROFILE" in
dtmalloc-top)	;;
*)		EVENT_TEST="(uint64_t)arg3 >= $DWATCH_MALLOC_MIN"
esac

############################################################ ACTIONS

if [ "$PROFILE" = "dtmalloc-top" ]; then
exec 9<<EOF
this int64_t	dtmalloc_delta;

BEGIN { printf("Cataloging malloc(9) activity ...") } /* probe ID $ID */

dtmalloc:::malloc /* probe ID $(( $ID + 1 )) */
{
	this->dtmalloc_delta = (int64_t)arg3;
}

dtmalloc:::free /* probe ID $(( $ID + 2 )) */
{
	this->dtmalloc_delta = -(int64_t)arg3;
}

dtmalloc:::malloc, dtmalloc:::free /* probe ID $(( $ID + 3 )) */
{
	@dtmalloc_bytes[probefunc] = sum(this->dtmalloc_delta);
	@dtmalloc_allocs[probefunc] =
		sum(this->dtmalloc_delta > 0 ? 1 : -1);
}
EOF
ACTIONS=$( cat <&9 )
ID=$(( $ID + 4 ))
fi

############################################################ EVENT TAG

# For the running catalog, override the default `UID.GID CMD[PID]: ' tag
# with ANSI cursor-homing and screen-clearing codes plus column headers.

if [ "$PROFILE" = "dtmalloc-top" ]; then
size=$( stty size 2> /dev/null )
rows="${size%% *}"
cols="${size#* }"

exec 9<<EOF
	printf("\033[H"); /* Position the cursor at top-left */
	printf("\033[J"); /* Clear display from cursor to end */

	/* Header line containing probe (left) and date (right) */
	printf("%-*s%s%Y%s\n",
		$(( ${cols:-80} - 20 )), "$PROBE",
		console ? "\033[32m" : "",
		walltimestamp,
		console ? "\033[39m" : "");

	/* Column headers */
	printf("%s%14s %10s %s%s\n",
		console ? "\033[1m" : "",
		"NET(B)",
		"BALANCE",
		"TYPE",
		console ? "\033[22m" : "");
EOF
EVENT_TAG=$( cat <&9 )
fi

############################################################ EVENT DETAILS

if [ "$PROFILE" = "dtmalloc-top" ]; then
exec 9<<EOF
	/* NB: Cumulative; not truncated between updates */
	printa("%@14d %@10d %s\n", @dtmalloc_bytes, @dtmalloc_allocs);
EOF
EVENT_DETAILS=$( cat <&9 )
elif [ ! "$CUSTOM_DETAILS" ]; then
exec 9<<EOF
	/*
	 * Print malloc(9) activity details
	 */
	printf("%s(9) type %s %d byte%s",
		probename,
		probefunc,
		(long)arg3,
		(long)arg3 == 1 ? "" : "s");
EOF
EVENT_DETAILS=$( cat <&9 )
fi

################################################################################
# END
################################################################################