From f4a3ae9308e34bcd704325a08879b2c1cfb74686 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Wed, 19 Nov 2014 12:27:11 -0600 Subject: [PATCH] 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 Acked-by: Steven Whitehouse --- fs/gfs2/rgrp.c | 13 +++++++++---- 1 file 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; -- 2.20.1