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Bug 1436739

Summary:	Sharding: Fix a performance bug
Product:	[Community] GlusterFS	Reporter:	Krutika Dhananjay <kdhananj>
Component:	sharding	Assignee:	Krutika Dhananjay <kdhananj>
Status:	CLOSED CURRENTRELEASE	QA Contact:	bugs <bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	mainline	CC:	bugs, jbyers
Target Milestone:	---	Keywords:	Triaged
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	glusterfs-3.11.0	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1437326 1437330 1438706 (view as bug list)		Environment:
Last Closed:	2017-05-30 18:48:21 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1437326, 1437330, 1438706, 1439731

Description Krutika Dhananjay 2017-03-28 14:20:23 UTC

Description of problem:

As per Sanjay Rao's inputs, there was a performance drop in random reads fio workload when run through vms hosted on sharded volumes.

Volume profile indicated a big difference between the number of lookups sent by FUSE and number of lookups received by individual bricks.

Through code reading, it was found that there is a performance bug in shard which was causing the translator to trigger unusually high number of lookups for cache invalidation even when there was no modification to the file.


Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
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Actual results:


Expected results:


Additional info:

Comment 1 Worker Ant 2017-03-28 14:23:33 UTC

REVIEW: https://review.gluster.org/16961 (features/shard: Pass the correct iatt for cache invalidation) posted (#1) for review on master by Krutika Dhananjay (kdhananj)

Comment 2 Worker Ant 2017-03-30 05:48:38 UTC

REVIEW: https://review.gluster.org/16961 (features/shard: Pass the correct iatt for cache invalidation) posted (#2) for review on master by Krutika Dhananjay (kdhananj)

Comment 3 Worker Ant 2017-03-30 06:15:59 UTC

COMMIT: https://review.gluster.org/16961 committed in master by Pranith Kumar Karampuri (pkarampu) 
------
commit dd5ada1f11d76b4c55c7c55d23718617f11a6c12
Author: Krutika Dhananjay <kdhananj>
Date:   Tue Mar 28 19:26:41 2017 +0530

    features/shard: Pass the correct iatt for cache invalidation
    
    This fixes a performance issue with shard which was causing
    the translator to trigger unusually high number of lookups
    for cache invalidation even when there was no modification to
    the file.
    
    In shard_common_stat_cbk(), it is local->prebuf that contains the
    aggregated size and block count as opposed to buf which only holds the
    attributes for the physical copy of base shard. Passing buf for
    inode_ctx invalidation would always set refresh to true since the file
    size in inode ctx contains the aggregated size and would never be same
    as @buf->ia_size. This was leading to every write/read being preceded
    by a lookup on the base shard even when the file underwent no
    modification.
    
    Change-Id: Ib0349291d2d01f3782d6d0bdd90c6db5e0609210
    BUG: 1436739
    Signed-off-by: Krutika Dhananjay <kdhananj>
    Reviewed-on: https://review.gluster.org/16961
    NetBSD-regression: NetBSD Build System <jenkins.org>
    CentOS-regression: Gluster Build System <jenkins.org>
    Smoke: Gluster Build System <jenkins.org>
    Reviewed-by: Pranith Kumar Karampuri <pkarampu>

Comment 4 Shyamsundar 2017-05-30 18:48:21 UTC

This bug is getting closed because a release has been made available that should address the reported issue. In case the problem is still not fixed with glusterfs-3.11.0, please open a new bug report.

glusterfs-3.11.0 has been announced on the Gluster mailinglists [1], packages for several distributions should become available in the near future. Keep an eye on the Gluster Users mailinglist [2] and the update infrastructure for your distribution.

[1] http://lists.gluster.org/pipermail/announce/2017-May/000073.html
[2] https://www.gluster.org/pipermail/gluster-users/