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Fix a bug that caused generated gmon.out profiles to be out of

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whack.  Use saturating arithmetic when incrementing a bucket.
Improve a few comments.

MFC after:	3 days
This commit is contained in:
jkoshy 2005-09-13 02:23:25 +00:00
parent 665ea151e9
commit 14b399b103
1 changed files with 31 additions and 10 deletions
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41
usr.sbin/pmcstat/pmcstat_log.c
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@ -30,6 +30,19 @@ __FBSDID("$FreeBSD$");
/*
* Transform a hwpmc(4) log into human readable form and into gprof(1)
* compatible profiles.
*
* Each executable object encountered in the log gets one 'gmon.out'
* profile per PMC. We currently track:
* - program executables
* - shared libraries loaded by the runtime loader
* - the runtime loader itself
* - the kernel.
* We do not track shared objects mapped in by dlopen() yet (this
* needs additional support from hwpmc(4)).
*
* 'gmon.out' profiles generated for a given sampling PMC are
* aggregates of all the samples for that particular executable
* object.
*/
#include <sys/param.h>
@ -80,7 +93,7 @@ struct pmcstat_string {
static LIST_HEAD(,pmcstat_string) pmcstat_string_hash[PMCSTAT_NHASH];
/*
* 'pmcstat_pmcs' is a mapping for PMC ids to their human-readable
* 'pmcstat_pmcrecord' is a mapping from PMC ids to human-readable
* names.
*/
@ -93,11 +106,17 @@ struct pmcstat_pmcrecord {
static LIST_HEAD(,pmcstat_pmcrecord) pmcstat_pmcs =
LIST_HEAD_INITIALIZER(&pmcstat_pmcs);
/*
* struct pmcstat_gmonfile tracks a given 'gmon.out' file. These
* files are mmap()'ed in as needed.
*/
struct pmcstat_gmonfile {
LIST_ENTRY(pmcstat_gmonfile) pgf_next; /* list of entries */
pmc_id_t pgf_pmcid; /* id of the associated pmc */
size_t pgf_nsamples; /* number of samples in this gmon.out */
const char *pgf_name; /* name of gmon.out file */
size_t pgf_nbuckets; /* #buckets in this gmon.out */
const char *pgf_name; /* pathname of gmon.out file */
size_t pgf_ndatabytes; /* number of bytes mapped */
void *pgf_gmondata; /* pointer to mmap'ed data */
};
@ -105,8 +124,6 @@ struct pmcstat_gmonfile {
static TAILQ_HEAD(,pmcstat_gmonfile) pmcstat_gmonfiles =
TAILQ_HEAD_INITIALIZER(pmcstat_gmonfiles);
#define GM_TO_BUCKETS(GM) ((uint16_t *) ((char *) (GM) + sizeof(*(GM))))
/*
* A 'pmcstat_image' structure describes an executable program on
* disk. 'pi_internedpath' is a cookie representing the pathname of
@ -218,7 +235,8 @@ pmcstat_gmon_create_file(struct pmcstat_gmonfile *pgf,
gm.lpc = image->pi_start;
gm.hpc = image->pi_end;
gm.ncnt = pgf->pgf_nsamples;
gm.ncnt = (pgf->pgf_nbuckets * sizeof(HISTCOUNTER)) +
sizeof(struct gmonhdr);
gm.version = GMONVERSION;
gm.profrate = 0; /* use ticks */
gm.histcounter_type = 0; /* compatibility with moncontrol() */
@ -514,10 +532,10 @@ pmcstat_image_increment_bucket(struct pmcstat_pcmap *map, uintfptr_t pc,
pgf->pgf_name = pmcstat_gmon_create_name(a->pa_samplesdir,
image, pmcid);
pgf->pgf_pmcid = pmcid;
pgf->pgf_nsamples = (image->pi_end - image->pi_start) /
pgf->pgf_nbuckets = (image->pi_end - image->pi_start) /
FUNCTION_ALIGNMENT; /* see <machine/profile.h> */
pgf->pgf_ndatabytes = sizeof(struct gmonhdr) +
pgf->pgf_nsamples * sizeof(HISTCOUNTER);
pgf->pgf_nbuckets * sizeof(HISTCOUNTER);
pmcstat_gmon_create_file(pgf, image);
@ -533,11 +551,14 @@ pmcstat_image_increment_bucket(struct pmcstat_pcmap *map, uintfptr_t pc,
bucket = (pc - map->ppm_lowpc) / FUNCTION_ALIGNMENT;
assert(bucket < pgf->pgf_nsamples);
assert(bucket < pgf->pgf_nbuckets);
hc = (HISTCOUNTER *) ((uintptr_t) pgf->pgf_gmondata +
sizeof(struct gmonhdr));
hc[bucket]++;
/* saturating add */
if (hc[bucket] < 0xFFFF)
hc[bucket]++;
}