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library <stat>: improve response to cpu offline/online

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With the addition of those new derived SUM values, any
CPUs taken offline or brought online would distort the
historical (delta) results.  So this patch just forces
a history reset when such transitions are encountered.

Reference(s):
. derived SUM provisions introduced
commit 2c86c4984a

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner 2016-12-31 00:00:00 -06:00 committed by Craig Small
parent f82ac70e13
commit 282ee362f0
1 changed files with 7 additions and 4 deletions
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11
proc/stat.c
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@ -76,6 +76,7 @@ struct hist_sys {
struct hist_tic {
int id;
int id_sav;
int numa_node;
int count;
struct stat_jifs new;
@ -635,14 +636,16 @@ reap_em_again:
, &cpu_ptr->new.idle, &cpu_ptr->new.iowait, &cpu_ptr->new.irq
, &cpu_ptr->new.sirq, &cpu_ptr->new.stolen
, &cpu_ptr->new.guest, &cpu_ptr->new.gnice))) {
int id_sav = cpu_ptr->id;
memmove(cpu_ptr, sum_ptr, sizeof(struct hist_tic));
cpu_ptr->id = id_sav;
cpu_ptr->id_sav = -1;
break; // we must tolerate cpus taken offline
}
stat_derive_unique(cpu_ptr);
++i;
// don't distort deltas when a cpu is taken offline or brought online
if (cpu_ptr->id != cpu_ptr->id_sav)
memcpy(&cpu_ptr->old, &cpu_ptr->new, sizeof(struct stat_jifs));
cpu_ptr->id_sav = cpu_ptr->id;
++cpu_ptr;
++i;
} while (i < info->cpus.hist.n_alloc);
if (i == info->cpus.hist.n_alloc && rc >= 8) {