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GFS2: Average in only non-zero round-trip times for congestion stats

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This patch changes function gfs2_rgrp_congested so that it only factors
in non-zero values into its average round trip time. If the round-trip
time is zero for a particular cpu, that cpu has obviously never dealt
with bouncing the resource group in question, so factoring in a zero
value will only skew the numbers. It also fixes a compile error on
some arches related to division.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Bob Peterson 2015-04-22 11:24:12 -05:00
parent f4a3ae9308
commit 0166b197c2
1 changed files with 7 additions and 3 deletions
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8
fs/gfs2/rgrp.c
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@ -1854,15 +1854,19 @@ static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
s64 srttb_diff;
s64 sqr_diff;
s64 var;
int cpu;
int cpu, nonzero = 0;
preempt_disable();
for_each_present_cpu(cpu) {
st = &per_cpu_ptr(sdp->sd_lkstats, cpu)->lkstats[LM_TYPE_RGRP];
if (st->stats[GFS2_LKS_SRTTB]) {
a_srttb += st->stats[GFS2_LKS_SRTTB];
nonzero++;
}
}
st = &this_cpu_ptr(sdp->sd_lkstats)->lkstats[LM_TYPE_RGRP];
a_srttb /= num_present_cpus();
if (nonzero)
do_div(a_srttb, nonzero);
r_dcount = st->stats[GFS2_LKS_DCOUNT];
var = st->stats[GFS2_LKS_SRTTVARB] +
gl->gl_stats.stats[GFS2_LKS_SRTTVARB];