From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bob Peterson Date: Thu, 25 Jun 2015 12:42:24 -0500 Subject: [Cluster-devel] [PATCH 01/16] GFS2: Use average srttb value in congestion calculations In-Reply-To: <1435254159-20788-1-git-send-email-rpeterso@redhat.com> References: <1435254159-20788-1-git-send-email-rpeterso@redhat.com> Message-ID: <1435254159-20788-2-git-send-email-rpeterso@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 6af2396..f39eedc 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; -- 2.1.0