upstream/opnsense-src
1
0
Fork 0
mirror of https://github.com/opnsense/src.git synced 2026-06-14 19:20:18 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

hwpmc: Permit the minimum sampling count to be set as a sysctl.

Browse source 
A rarely occurring event (e.g. an event that occurs less than 1000
times during execution of a program) may require a lower minimum
threshold than 1000.  Replace the hardcoded 1000 with a sysctl that
the administrator can use to permit smaller sampling count values.

Reviewed by:	mhorne, mav
Sponsored by:	University of Cambridge, Google, Inc.
Differential Revision:	https://reviews.freebsd.org/D35400
This commit is contained in:
John Baldwin 2022-06-09 11:05:34 -07:00
parent 74536fca79
commit ca341f3cf5
2 changed files with 29 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
share/man/man4/hwpmc.4
View file

@ -416,6 +416,9 @@ The size in kilobytes of each log buffer used by
.Nm Ns 's
logging function.
The default buffer size is 4KB.
.It Va kern.hwpmc.mincount Pq integer, read-write
The minimum sampling rate for sampling mode PMCs.
The default count is 1000 events.
.It Va kern.hwpmc.mtxpoolsize Pq integer, read-only
The size of the spin mutex pool used by the PMC driver.
The default is 32.

38
sys/dev/hwpmc/hwpmc_mod.c
View file

@ -363,6 +363,14 @@ SYSCTL_INT(_kern_hwpmc, OID_AUTO, threadfreelist_max, CTLFLAG_RW,
"maximum number of available thread entries before freeing some");
/*
* kern.hwpmc.mincount -- minimum sample count
*/
static u_int pmc_mincount = 1000;
SYSCTL_INT(_kern_hwpmc, OID_AUTO, mincount, CTLFLAG_RWTUN,
&pmc_mincount, 0,
"minimum count for sampling counters");
/*
* security.bsd.unprivileged_syspmcs -- allow non-root processes to
* allocate system-wide PMCs.
@ -3950,13 +3958,16 @@ pmc_syscall_handler(struct thread *td, void *syscall_args)
/* XXX set lower bound on sampling for process counters */
if (PMC_IS_SAMPLING_MODE(mode)) {
/*
* Don't permit requested sample rate to be less than 1000
* Don't permit requested sample rate to be
* less than pmc_mincount.
*/
if (pa.pm_count < 1000)
log(LOG_WARNING,
"pmcallocate: passed sample rate %ju - setting to 1000\n",
(uintmax_t)pa.pm_count);
pmc->pm_sc.pm_reloadcount = MAX(1000, pa.pm_count);
if (pa.pm_count < MAX(1, pmc_mincount))
log(LOG_WARNING, "pmcallocate: passed sample "
"rate %ju - setting to %u\n",
(uintmax_t)pa.pm_count,
MAX(1, pmc_mincount));
pmc->pm_sc.pm_reloadcount = MAX(MAX(1, pmc_mincount),
pa.pm_count);
} else
pmc->pm_sc.pm_initial = pa.pm_count;
@ -4474,13 +4485,16 @@ pmc_syscall_handler(struct thread *td, void *syscall_args)
if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm))) {
/*
* Don't permit requested sample rate to be less than 1000
* Don't permit requested sample rate to be
* less than pmc_mincount.
*/
if (sc.pm_count < 1000)
log(LOG_WARNING,
"pmcsetcount: passed sample rate %ju - setting to 1000\n",
(uintmax_t)sc.pm_count);
pm->pm_sc.pm_reloadcount = MAX(1000, sc.pm_count);
if (sc.pm_count < MAX(1, pmc_mincount))
log(LOG_WARNING, "pmcsetcount: passed sample "
"rate %ju - setting to %u\n",
(uintmax_t)sc.pm_count,
MAX(1, pmc_mincount));
pm->pm_sc.pm_reloadcount = MAX(MAX(1, pmc_mincount),
sc.pm_count);
} else
pm->pm_sc.pm_initial = sc.pm_count;
}