Bug 484158
| Summary: | FEAT: feature request. disable iostat collection in gendisk | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 5 | Reporter: | Chinang Ma <chinang.ma> | ||||
| Component: | kernel | Assignee: | Jerome Marchand <jmarchan> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Red Hat Kernel QE team <kernel-qe> | ||||
| Severity: | high | Docs Contact: | |||||
| Priority: | low | ||||||
| Version: | 5.3 | CC: | cward, dhoward, dzickus, matthew.r.wilcox | ||||
| Target Milestone: | rc | Keywords: | ZStream | ||||
| Target Release: | 5.4 | ||||||
| Hardware: | All | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | |||||||
| : | 488544 646908 (view as bug list) | Environment: | |||||
| Last Closed: | 2009-09-02 08:58:50 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: | 488544, 646908, 651809 | ||||||
| Attachments: |
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Created attachment 332619 [details]
control iostat with sysfs file
RHEL 5.3 has 1.5% OLTP performance regression compare to RHEL5.2. We back-ported Jens Axboe's iostat control patch to RHEL5.2. When iostats was disable using sysfs file, we recovered 1.2% of the regression. we are looking into getting this patch into 5.4. fyi.. The patch "block: fix oops in blk_queue_io_stat()" (git# fb8ec18c316d869271137c97320dbfd2def56569) has to be backported too in order to avoid NULL pointer dereferencing. Upstream patch is buggy. It doesn't turn off accounting completely and that may leave io stats in an inconsistent state. I'm working on its correction. in kernel-2.6.18-146.el5 You can download this test kernel from http://people.redhat.com/dzickus/el5 Please do NOT transition this bugzilla state to VERIFIED until our QE team has sent specific instructions indicating when to do so. However feel free to provide a comment indicating that this fix has been verified. ~~ Attention - RHEL 5.4 Beta Released! ~~ RHEL 5.4 Beta has been released! There should be a fix present in the Beta release that addresses this particular request. Please test and report back results here, at your earliest convenience. RHEL 5.4 General Availability release is just around the corner! If you encounter any issues while testing Beta, please describe the issues you have encountered and set the bug into NEED_INFO. If you encounter new issues, please clone this bug to open a new issue and request it be reviewed for inclusion in RHEL 5.4 or a later update, if it is not of urgent severity. Please do not flip the bug status to VERIFIED. Only post your verification results, and if available, update Verified field with the appropriate value. Questions can be posted to this bug or your customer or partner representative. I have verified that RHEL 5.4 beta (2.6.18-155.el5 ) has iostat disabling option avaliable under /sys/block/<device>/queue/iostats. Tested with OLTP workload on a Nehalem 2 sockets server with 16 logical CPUs. We saw ~4% increase in performance when iostats is disabled (changed from 1 to 0 ) . This made RHEL 5.4 OLTP peroformance on par with RHEL 5.2. 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 therefore 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/RHSA-2009-1243.html |
Description of problem: RHEL 5.3 have partition io stats enabled in the kernel (as seen in iostats -x) and caused performance regression in OLTP workload. Version-Release number of selected component (if applicable): RHEL 5.3 How reproducible: Test with OLTP workload (TPC-C) in Quad-core Xeon DP system. ~ 1% performance regression. Steps to Reproduce: Run OLTP workload in RHEL5.2 (TPC-C) and collect profile. run 5.3 with same workload. 1.3% cycles was attributed to get_partstat() 1. 2. 3. Actual results: Expected results: Additional info: Feature request. please backport 2.6-git iostat enable/disable queue knob to EL 5.4. this expose a sysfs block device switch(/sys/block/sd<xx>/queue/iostat) that disable iostat collection in kernel. locations: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 commit bc58ba9468d94d62c56ab9b47173583ec140b165 Author: Jens Axboe <jens.axboe> Date: Fri Jan 23 10:54:44 2009 +0100 block: add sysfs file for controlling io stats accounting This allows us to turn off disk stat accounting completely, for the cases where the 0.5-1% reduction in system time is important. Signed-off-by: Jens Axboe <jens.axboe>