Bug 748796

Summary:	slow read/write speeds to /dev/shm on Dell T3500 and T5500 machines
Product:	Red Hat Enterprise Linux 5	Reporter:	csb sysadmin <admin>
Component:	kernel	Assignee:	Red Hat Kernel Manager <kernel-mgr>
Status:	CLOSED WONTFIX	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	5.7	CC:	admin
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2014-06-02 13:05:40 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description csb sysadmin 2011-10-25 12:04:42 UTC

Description of problem:

I've noticed really poor sequential I/O performance to /dev/shm on Dell T3500 and T5500 workstations with RHEL5 kernels from 2.6.18-164.11.1.el5 to 290. Run a dd if=/dev/zero of=/someFile bs=4k count=somethingBig in /dev/shm and I'm getting 157MB/s on writes and 206MB/s on reads . Should be getting 2.6GB/s on writes and reads as on RHEL6.

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

2.6.18-164.11.1.el5 to 290 kernels

How reproducible:

All the time on multiple T3500 and T5500 systems.

Steps to Reproduce:
1. cd /dev/shm
2. dd if=/dev/zero of=/someFile bs=4k count=somethingBig
3. dd if=someFile of=/dev/zero bs=4k

Actual results:

157MB/s on writes and 206MB/s on reads

Expected results:

2.6GB/s+ on writes and reads

Additional info:

Doesn't happen with RHEL6 2.6.32 kernels

Comment 1 csb sysadmin 2012-01-30 14:57:50 UTC

still the same with -304 kernel

Comment 2 RHEL Program Management 2014-03-07 12:42:14 UTC

This bug/component is not included in scope for RHEL-5.11.0 which is the last RHEL5 minor release. This Bugzilla will soon be CLOSED as WONTFIX (at the end of RHEL5.11 development phase (Apr 22, 2014)). Please contact your account manager or support representative in case you need to escalate this bug.

Comment 3 RHEL Program Management 2014-06-02 13:05:40 UTC

Thank you for submitting this request for inclusion in Red Hat Enterprise Linux 5. We've carefully evaluated the request, but are unable to include it in RHEL5 stream. If the issue is critical for your business, please provide additional business justification through the appropriate support channels (https://access.redhat.com/site/support).