[Bugs] [Bug 1635972] Low Random write IOPS in VM workloads

bugzilla at redhat.com bugzilla at redhat.com
Fri Oct 5 14:37:54 UTC 2018


Worker Ant <bugzilla-bot at gluster.org> changed:

           What    |Removed                     |Added
             Status|NEW                         |MODIFIED

--- Comment #3 from Worker Ant <bugzilla-bot at gluster.org> ---
COMMIT: https://review.gluster.org/21338 committed in release-5 by "Shyamsundar
Ranganathan" <srangana at redhat.com> with a commit message- cluster/afr: Make
data eager-lock decision based on number of locks

For both Virt and block workloads the file is opened multiple times
leading to dynamically setting eager-lock to off for the workload.
Instead of depending on the number-of-open-fds, if we change the
logic to depend on number of inodelks, then it will give better
performance than the earlier logic. When there is an eager-lock
and number of inodelks is more than 1 we know that there is a
conflicting lock, so depend on that information to decide whether
to keep the current transaction go through delayed-post-op or not.

Locks xlator doesn't have implementation to query number of locks in
fxattrop in releases older than 3.10 so to keep things backward
compatible in 3.12, data transactions will use new logic where as
fxattrop transactions will use old logic. I am planning to send one
more patch which makes metadata domain locks also depend on

Profile info for a dd of 500MB to a file with another fd opened
on the file using exec 250>filename

Without this patch:
 0.14      67.41 us      16.72 us    3870.82 us  892 FINODELK
 0.59     279.87 us      95.71 us    2085.89 us  898 FXATTROP
 3.46     366.43 us      81.75 us    6952.79 us 4000 WRITE
95.79  148733.99 us   50568.12 us  919127.86 us  273 FSYNC

With this patch:
 0.00      51.01 us      38.07 us      80.16 us    4 FINODELK
 0.00     235.43 us     235.43 us     235.43 us    1 TRUNCATE
 0.00     125.07 us      56.80 us     193.33 us    2 GETXATTR
 0.00     135.86 us      62.13 us     209.59 us    2  INODELK
 0.00     197.88 us     155.39 us     253.90 us    4 FXATTROP
 0.00     450.59 us     394.28 us     506.89 us    2  XATTROP
 0.00      56.96 us      19.06 us     406.59 us   23    FLUSH
37.81  273648.93 us      48.43 us 6017657.05 us   44   LOOKUP
62.18    4951.86 us      93.80 us 1143154.75 us 3999    WRITE

postgresql benchmark performance changed from ~1130 TPS to ~2300TPS
randio fio job inside Ovirt based VM went from ~600IOPs to ~2000IOPS

fixes bz#1635972
Change-Id: If7f7388d2f08cf7f17ca517a4ea222560661dc36
Signed-off-by: Pranith Kumar K <pkarampu at redhat.com>

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