[Bugs] [Bug 1408809] [Perf] : significant Performance regression seen with disperse volume when compared with 3.1.3

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1408809



--- Comment #10 from Worker Ant <bugzilla-bot at gluster.org> ---
COMMIT: https://review.gluster.org/16821 committed in master by Pranith Kumar
Karampuri (pkarampu at redhat.com) 
------
commit 78c5c5637104cf79578d0fb9173647c9c3421177
Author: Pranith Kumar K <pkarampu at redhat.com>
Date:   Thu Mar 2 07:14:14 2017 +0530

    cluster/ec: Introduce optimistic changelog in EC

    Problem: Fix to https://bugzilla.redhat.com/show_bug.cgi?id=1316873 has
made
    changes to set dirty flag before every update fop, data or metadata, and
unset
    it after successful operation. That makes some of the fops very slow such
as
    entry operations or metadata operations.

    Solution: File data operations are the only operation which take some time
and
    setting dirty flag before a fop and unsetting it after serves the purpose
as
    probability of failure of a fop is high when the time duration is more. For
all
    the other operations, set dirty flag at the end of the fop, if any brick is
    down and need heal.

    Providing following option to choose between high performance or better
heal
    marking for metadata and entry fops.

    Set/Unset dirty flag for every update fop at the start of the fop. If ON,
this
    option impacts performance of entry operations or metadata operations as it
    will set dirty flag at the start and unset it at the end of ALL update fop.
If
    OFF and all the bricks are good, dirty flag will be set at the start only
for
    file fops For metadata and entry fops dirty flag will not be set at the
start,
    if all the bricks are good. This does not impact performance for metadata
    operations and entry operation but has a very small window to miss marking
    entry as dirty in case it is required to be healed.

    Thanks to Xavi and Ashish for the design
    Picked the .t file from Ashish' patch https://review.gluster.org/16298

    BUG: 1408809
    Change-Id: I3ce860063f0e2901e50754dcfc3e4ed22daf819f
    Signed-off-by: Pranith Kumar K <pkarampu at redhat.com>
    Reviewed-on: https://review.gluster.org/16821
    Smoke: Gluster Build System <jenkins at build.gluster.org>
    Reviewed-by: Xavier Hernandez <xhernandez at datalab.es>
    Tested-by: Xavier Hernandez <xhernandez at datalab.es>
    NetBSD-regression: NetBSD Build System <jenkins at build.gluster.org>
    CentOS-regression: Gluster Build System <jenkins at build.gluster.org>

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