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Add explicit static DTrace tracing to the callout mechanism, capturing

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pointers to the callout handler just before and just after the callout
it invoked.  I attempted to do this in a manner congruent to tracing in
Solaris's callout mechanism, but couldn't quite use the same names due
to convention and syntax differences.

Example DTrace script to generate a distribution graph of callout
execution times:

callout_execute:::callout_start
{
        self->cstart = timestamp;
}

callout_execute:::callout_end
{

        @length = quantize(timestamp - self->cstart);
}

Reviewed by:	jb
MFC after:	3 days
This commit is contained in:
Robert Watson 2009-01-24 10:22:49 +00:00
parent cff548f0dd
commit 91dd9aae1a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=187664
1 changed files with 15 additions and 0 deletions
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15
sys/kern/kern_timeout.c
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@ -37,6 +37,8 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_kdtrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
@ -49,10 +51,19 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sdt.h>
#include <sys/sleepqueue.h>
#include <sys/sysctl.h>
#include <sys/smp.h>
SDT_PROVIDER_DEFINE(callout_execute);
SDT_PROBE_DEFINE(callout_execute, kernel, , callout_start);
SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_start, 0,
"struct callout *");
SDT_PROBE_DEFINE(callout_execute, kernel, , callout_end);
SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_end, 0,
"struct callout *");
static int avg_depth;
SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
"Average number of items examined per softclock call. Units = 1/1000");
@ -395,7 +406,11 @@ softclock(void *arg)
binuptime(&bt1);
#endif
THREAD_NO_SLEEPING();
SDT_PROBE(callout_execute, kernel, ,
callout_start, c, 0, 0, 0, 0);
c_func(c_arg);
SDT_PROBE(callout_execute, kernel, ,
callout_end, c, 0, 0, 0, 0);
THREAD_SLEEPING_OK();
#ifdef DIAGNOSTIC
binuptime(&bt2);