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author | phk <phk@FreeBSD.org> | 2003-03-15 21:59:06 +0000 |
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committer | phk <phk@FreeBSD.org> | 2003-03-15 21:59:06 +0000 |
commit | f432014308d6b21386e15affbbca62043615671d (patch) | |
tree | c322a33c0275fefd9ca33cd377e3d6f459cb9a8c /lib/libdevstat/devstat.c | |
parent | d16675cd85efe1cde6bf077376276f3de06f0263 (diff) | |
download | FreeBSD-src-f432014308d6b21386e15affbbca62043615671d.zip FreeBSD-src-f432014308d6b21386e15affbbca62043615671d.tar.gz |
Run a revision of the devstat interface:
Kernel:
Change statistics to use the *uptime() timescale (ie: relative to
boottime) rather than the UTC aligned timescale. This makes the
device statistics code oblivious to clock steps.
Change timestamps to bintime format, they are cheaper.
Remove the "busy_count", and replace it with two counter fields:
"start_count" and "end_count", which are updated in the down and
up paths respectively. This removes the locking constraint on
devstat.
Add a timestamp argument to devstat_start_transaction(), this will
normally be a timestamp set by the *_bio() function in bp->bio_t0.
Use this field to calculate duration of I/O operations.
Add two timestamp arguments to devstat_end_transaction(), one is
the current time, a NULL pointer means "take timestamp yourself",
the other is the timestamp of when this transaction started (see
above).
Change calculation of busy_time to operate on "the salami principle":
Only when we are idle, which we can determine by the start+end
counts being identical, do we update the "busy_from" field in the
down path. In the up path we accumulate the timeslice in busy_time
and update busy_from.
Change the byte_* and num_* fields into two arrays: bytes[] and
operations[].
Userland:
Change the misleading "busy_time" name to be called "snap_time" and
make the time long double since that is what most users need anyway,
fill it using clock_gettime(CLOCK_MONOTONIC) to put it on the same
timescale as the kernel fields.
Change devstat_compute_etime() to operate on struct bintime.
Remove the version 2 legacy interface: the change to bintime makes
compatibility far too expensive.
Fix a bug in systat's "vm" page where boot relative busy times would
be bogus.
Bump __FreeBSD_version to 500107
Review & Collaboration by: ken
Diffstat (limited to 'lib/libdevstat/devstat.c')
-rw-r--r-- | lib/libdevstat/devstat.c | 126 |
1 files changed, 32 insertions, 94 deletions
diff --git a/lib/libdevstat/devstat.c b/lib/libdevstat/devstat.c index 9c715d8..e5047be 100644 --- a/lib/libdevstat/devstat.c +++ b/lib/libdevstat/devstat.c @@ -315,6 +315,7 @@ devstat_getdevs(kvm_t *kd, struct statinfo *stats) int retval = 0; struct devinfo *dinfo; const char *func_name = "devstat_getdevs"; + struct timespec ts; dinfo = stats->dinfo; @@ -327,8 +328,8 @@ devstat_getdevs(kvm_t *kd, struct statinfo *stats) oldnumdevs = dinfo->numdevs; oldgeneration = dinfo->generation; - /* Get the current time when we get the stats */ - gettimeofday(&stats->busy_time, NULL); + clock_gettime(CLOCK_MONOTONIC, &ts); + stats->snap_time = ts.tv_sec + ts.tv_nsec * 1e-9; if (kd == NULL) { /* If this is our first time through, mem_ptr will be null. */ @@ -338,7 +339,7 @@ devstat_getdevs(kvm_t *kd, struct statinfo *stats) * error. Don't bother setting the error string, since * getnumdevs() has already done that for us. */ - if ((dinfo->numdevs = getnumdevs()) < 0) + if ((dinfo->numdevs = devstat_getnumdevs(NULL)) < 0) return(-1); /* @@ -371,9 +372,9 @@ devstat_getdevs(kvm_t *kd, struct statinfo *stats) if (errno == ENOMEM) { /* * No need to set the error string here, - * getnumdevs() will do that if it fails. + * devstat_getnumdevs() will do that if it fails. */ - if ((dinfo->numdevs = getnumdevs()) < 0) + if ((dinfo->numdevs = devstat_getnumdevs(NULL)) < 0) return(-1); dssize = (dinfo->numdevs * @@ -403,7 +404,7 @@ devstat_getdevs(kvm_t *kd, struct statinfo *stats) * This is of course non-atomic, but since we are working * on a core dump, the generation is unlikely to change */ - if ((dinfo->numdevs = getnumdevs()) == -1) + if ((dinfo->numdevs = devstat_getnumdevs(NULL)) == -1) return(-1); if ((dinfo->mem_ptr = get_devstat_kvm(kd)) == NULL) return(-1); @@ -430,8 +431,8 @@ devstat_getdevs(kvm_t *kd, struct statinfo *stats) * necessary. */ if (oldgeneration != dinfo->generation) { - if (getnumdevs() != dinfo->numdevs) { - if ((dinfo->numdevs = getnumdevs()) < 0) + if (devstat_getnumdevs(NULL) != dinfo->numdevs) { + if ((dinfo->numdevs = devstat_getnumdevs(NULL)) < 0) return(-1); dssize = (dinfo->numdevs * sizeof(struct devstat)) + sizeof(long); @@ -1142,21 +1143,21 @@ compute_stats(struct devstat *current, struct devstat *previous, DSM_NONE)); } + +/* This is 1/2^64 */ +#define BINTIME_SCALE 5.42101086242752217003726400434970855712890625e-20 + long double -devstat_compute_etime(struct timeval cur_time, struct timeval prev_time) +devstat_compute_etime(struct bintime *cur_time, struct bintime *prev_time) { - struct timeval busy_time; - u_int64_t busy_usec; long double etime; - timersub(&cur_time, &prev_time, &busy_time); - - busy_usec = busy_time.tv_sec; - busy_usec *= 1000000; - busy_usec += busy_time.tv_usec; - etime = busy_usec; - etime /= 1000000; - + etime = cur_time->sec; + etime += cur_time->frac * BINTIME_SCALE; + if (prev_time != NULL) { + etime -= prev_time->sec; + etime -= prev_time->frac * BINTIME_SCALE; + } return(etime); } @@ -1186,21 +1187,21 @@ devstat_compute_statistics(struct devstat *current, struct devstat *previous, return(-1); } - totalbytesread = current->bytes_read - - ((previous) ? previous->bytes_read : 0); - totalbyteswrite = current->bytes_written - - ((previous) ? previous->bytes_written : 0); + totalbytesread = current->bytes[DEVSTAT_READ] - + ((previous) ? previous->bytes[DEVSTAT_READ] : 0); + totalbyteswrite = current->bytes[DEVSTAT_WRITE] - + ((previous) ? previous->bytes[DEVSTAT_WRITE] : 0); totalbytes = totalbytesread + totalbyteswrite; - totaltransfersread = current->num_reads - - ((previous) ? previous->num_reads : 0); + totaltransfersread = current->operations[DEVSTAT_READ] - + ((previous) ? previous->operations[DEVSTAT_READ] : 0); - totaltransferswrite = current->num_writes - - ((previous) ? previous->num_writes : 0); + totaltransferswrite = current->operations[DEVSTAT_WRITE] - + ((previous) ? previous->operations[DEVSTAT_WRITE] : 0); - totaltransfersother = current->num_other - - ((previous) ? previous->num_other : 0); + totaltransfersother = current->operations[DEVSTAT_NO_DATA] - + ((previous) ? previous->operations[DEVSTAT_NO_DATA] : 0); totaltransfers = totaltransfersread + totaltransferswrite + totaltransfersother; @@ -1496,7 +1497,7 @@ get_devstat_kvm(kvm_t *kd) char *rv = NULL; const char *func_name = "get_devstat_kvm"; - if ((num_devs = getnumdevs()) <= 0) + if ((num_devs = devstat_getnumdevs(kd)) <= 0) return(NULL); error = 0; if (KREADNL(kd, X_DEVICE_STATQ, dhead) == -1) @@ -1510,7 +1511,7 @@ get_devstat_kvm(kvm_t *kd) func_name); return(NULL); } - gen = getgeneration(); + gen = devstat_getgeneration(kd); memcpy(rv, &gen, sizeof(gen)); wp = sizeof(gen); /* @@ -1536,66 +1537,3 @@ get_devstat_kvm(kvm_t *kd) } return(rv); } - -/* - * Compatability functions for libdevstat 2. These are deprecated and may - * eventually be removed. - */ -int -getnumdevs(void) -{ - return(devstat_getnumdevs(NULL)); -} - -long -getgeneration(void) -{ - return(devstat_getgeneration(NULL)); -} - -int -getversion(void) -{ - return(devstat_getversion(NULL)); -} - -int -checkversion(void) -{ - return(devstat_checkversion(NULL)); -} - -int -getdevs(struct statinfo *stats) -{ - return(devstat_getdevs(NULL, stats)); -} - -int -selectdevs(struct device_selection **dev_select, int *num_selected, - int *num_selections, long *select_generation, - long current_generation, struct devstat *devices, int numdevs, - struct devstat_match *matches, int num_matches, - char **dev_selections, int num_dev_selections, - devstat_select_mode select_mode, int maxshowdevs, - int perf_select) -{ - - return(devstat_selectdevs(dev_select, num_selected, num_selections, - select_generation, current_generation, devices, numdevs, - matches, num_matches, dev_selections, num_dev_selections, - select_mode, maxshowdevs, perf_select)); -} - -int -buildmatch(char *match_str, struct devstat_match **matches, - int *num_matches) -{ - return(devstat_buildmatch(match_str, matches, num_matches)); -} - -long double -compute_etime(struct timeval cur_time, struct timeval prev_time) -{ - return(devstat_compute_etime(cur_time, prev_time)); -} |