Bug 1244585

Summary:	Reduce lock contention in __tz_convert()
Product:	Red Hat Enterprise Linux 6	Reporter:	Rogan Kyuseok Lee <kyulee>
Component:	glibc	Assignee:	Marek Polacek <mpolacek>
Status:	CLOSED ERRATA	QA Contact:	Arjun Shankar <ashankar>
Severity:	medium	Docs Contact:	Lenka Špačková <lkuprova>
Priority:	unspecified
Version:	6.6	CC:	ashankar, codonell, fweimer, jhan, mnewsome, mpolacek, pfrankli
Target Milestone:	rc	Keywords:	Patch
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	glibc-2.12-1.174.el6	Doc Type:	Release Note
Doc Text:	Reduced lock contention and increased performance for threaded applications calling localtime_r() Lock contention in the localtime_r() function previously decreased performance for threaded applications that needed to call this function frequently. The lock acquisition in the glibc library's internal routines has been reorganized to decrease the possibility of lock contention.	Story Points:	---
Clone Of:
Clones:	1322539 (view as bug list)		Environment:
Last Closed:	2016-05-10 21:27:23 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:	1172231, 1271375, 1322539

Description Rogan Kyuseok Lee 2015-07-20 05:02:45 UTC

Description of problem:

Customer has found a possible lock contention on glibc's localtime_r() and asked to backport it. All RHEL variables from 4 to 7 don't have this fix.

"This patch is an "easy win" partial fix for BZ #16145, which notes
the heavy contention on tzset_lock when multiple threads are converting
times with localtime_r().

In __tz_convert(), the lock does not need to be held after
__tzfile_compute() / __tz_compute() have been called, so we can move the
unlock up.  At this point there is still significant work to be done in
__offtime(), so we see some improvement (in my testing with 8 cores
banging on localtime_r(), ~20% improvement in throughput)."
-- https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=6807b1db8233ed84671f061b5d825622233df303


Version-Release number of selected component (if applicable):
- glibc-2.12-1.149.el6


How reproducible:
- 100% 


Steps to Reproduce:
1. No sure at this moment 
2.
3.


Actual results:
- No fix 

Expected results:
- Apply the upstream fix 


Additional info:

Comment 14 errata-xmlrpc 2016-05-10 21:27:23 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-0834.html