Bug 245776

Summary:	Purge count math is not correct in glock trimming patch
Product:	[Retired] Red Hat Cluster Suite	Reporter:	Wendy Cheng <nobody+wcheng>
Component:	GFS-kernel	Assignee:	Wendy Cheng <nobody+wcheng>
Status:	CLOSED ERRATA	QA Contact:	GFS Bugs <gfs-bugs>
Severity:	medium	Docs Contact:
Priority:	high
Version:	4	CC:	morissette
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	RHBA-2007-0998	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2007-11-21 21:14:29 UTC	Type:	---
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:	247650

Description Wendy Cheng 2007-06-26 17:23:25 UTC

Description of problem:
Previous CVS check-in did a last minute change with the way purge count 
was calculated. The intention was to trim glocks evenly across all the 
hash buckets and apparently the size of hash array was overlooked. It 
ends up with zero trimming count most of the time. This virtually makes 
glock trimming patch a void feature. Need to fix this asap. 

Version-Release number of selected component (if applicable):
RHEL 4.5

How reproducible:
Most of the time unless accumulated glock count is well above 8k. 

Steps to Reproduce:
1. Untar a tar file with lots of small files
2. Issue gfs_tool lockdump to see the glock count.
3. Issue "gfs_tool settune <mnt> glock_purge 100" to trim the glock
  
Actual results:
Glock count could stay constant for the duration of the mount time.

Expected results:
Glock count should go down gradually (around 6~10 minutes)

Additional info:

Comment 2 Wendy Cheng 2007-06-26 17:42:30 UTC

Thanks to Barry Marson. The regression was found in his SPECsfs runs.

Comment 4 Wendy Cheng 2007-06-26 20:40:05 UTC

Checked into RHEL4 and RHEL4.5 CVS branches.

Comment 9 errata-xmlrpc 2007-11-21 21:14:29 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2007-0998.html