[Cluster-devel] [GFS2 PATCH 0/6] [resend] GFS2: Rework rgrp glock congestion functions for intra-node

[Bob Peterson <rpeterso@redhat.com>]

On 06 November 2017, I posted this six-part patch set for rgrp glock congestion
and got no response. I'm resending it here to give people one last
opportunity to review it before I push it to the for-next branch. It has
been rebased, but otherwise unchanged.
---
Original patch set description:

On 02 November, I posted a patch for this, but Steve Whitehouse pointed out
a check that didn't look right. I tested it and found it to be unnecessary,
so I remove it.

Steve also pointed out that the patch tried to do too much. He asked which
part of the patch actually made the performance gains.

Based on Steve's suggestions, I've broken the changes into six patches for this
patchset. The first five are all refactoring to make the code simpler and
more easy to follow. Much of the complex special-case checks were consolidated
from the variety of locations to more centralized functions. The actual
performance gains are accomplished by the very last patch, "GFS2: Add checks
for intra-node congestion". So strictly speaking, the last patch is the only
patch we really need. But without the others, today's kludgy code becomes
even more kludgy and harder to read.

In doing all this, I did find a minor problem with the previous version's
logic, and fixed it.

I retested iozone performance and fragmentation. It is pretty much the same
as I documented for the previous patch:

Bob Peterson (6):
  GFS2: Simplify gfs2_rgrp_used_recently
  GFS2: Check gfs2_rgrp_used_recently inside gfs2_rgrp_congested
  GFS2: Refactor function fast_to_acquire
  GFS2: Simplify by checking fast_to_acquire in gfs2_rgrp_congested
  GFS2: Split gfs2_rgrp_congested into dlm and non-dlm cases
  GFS2: Add checks for intra-node congestion

 fs/gfs2/rgrp.c | 176 +++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 134 insertions(+), 42 deletions(-)

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2.14.3