Bug 748796 - slow read/write speeds to /dev/shm on Dell T3500 and T5500 machines
Summary: slow read/write speeds to /dev/shm on Dell T3500 and T5500 machines
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.7
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: rc
: ---
Assignee: Red Hat Kernel Manager
QA Contact: Red Hat Kernel QE team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-10-25 12:04 UTC by csb sysadmin
Modified: 2016-03-07 13:43 UTC (History)
1 user (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2014-06-02 13:05:40 UTC
Target Upstream Version:

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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).
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