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authorBob Peterson <rpeterso@redhat.com>2014-11-19 12:27:11 -0600
committerBob Peterson <rpeterso@redhat.com>2015-04-24 07:57:08 -0500
commitf4a3ae9308e34bcd704325a08879b2c1cfb74686 (patch)
tree2002df7eacb9f6d17fedc46057eae3159d9cd68c /fs/gfs2
parentbb0fd7ab0986105765d11baa82e619c618a235aa (diff)
downloadlinux-f4a3ae9308e34bcd704325a08879b2c1cfb74686.tar.bz2
GFS2: Use average srttb value in congestion calculations
This patch changes function gfs2_rgrp_congested so that it uses an average srttb (smoothed round trip time for blocking rgrp glocks) rather than the CPU-specific value. If we use the CPU-specific value it can incorrectly report no contention when there really is contention due to the glock processing occurring on a different CPU. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2')
-rw-r--r--fs/gfs2/rgrp.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 6af2396a317c..f39eedc1af76 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1850,14 +1850,19 @@ static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
const struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_lkstats *st;
s64 r_dcount, l_dcount;
- s64 r_srttb, l_srttb;
+ s64 l_srttb, a_srttb = 0;
s64 srttb_diff;
s64 sqr_diff;
s64 var;
+ int cpu;
preempt_disable();
+ for_each_present_cpu(cpu) {
+ st = &per_cpu_ptr(sdp->sd_lkstats, cpu)->lkstats[LM_TYPE_RGRP];
+ a_srttb += st->stats[GFS2_LKS_SRTTB];
+ }
st = &this_cpu_ptr(sdp->sd_lkstats)->lkstats[LM_TYPE_RGRP];
- r_srttb = st->stats[GFS2_LKS_SRTTB];
+ a_srttb /= num_present_cpus();
r_dcount = st->stats[GFS2_LKS_DCOUNT];
var = st->stats[GFS2_LKS_SRTTVARB] +
gl->gl_stats.stats[GFS2_LKS_SRTTVARB];
@@ -1866,10 +1871,10 @@ static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
l_srttb = gl->gl_stats.stats[GFS2_LKS_SRTTB];
l_dcount = gl->gl_stats.stats[GFS2_LKS_DCOUNT];
- if ((l_dcount < 1) || (r_dcount < 1) || (r_srttb == 0))
+ if ((l_dcount < 1) || (r_dcount < 1) || (a_srttb == 0))
return false;
- srttb_diff = r_srttb - l_srttb;
+ srttb_diff = a_srttb - l_srttb;
sqr_diff = srttb_diff * srttb_diff;
var *= 2;