Bug 510257
| Summary: | allow more flexibility for read_ahead_kb store | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 5 | Reporter: | Bryn M. Reeves <bmr> | ||||
| Component: | kernel | Assignee: | Danny Feng <dfeng> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Red Hat Kernel QE team <kernel-qe> | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 5.5 | CC: | cward, dzickus, tao | ||||
| Target Milestone: | rc | ||||||
| Target Release: | --- | ||||||
| Hardware: | All | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2010-03-30 07:30:35 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: | 526775, 533192 | ||||||
| Attachments: |
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Created attachment 350941 [details] Commit from comment #0 rediffed for RHEL5 This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release. in kernel-2.6.18-168.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 Customers and Partners - RHEL 5.5 Beta is now available on RHN ~~ RHEL 5.5 Beta has been released! There should be a fix present in this release that addresses your request. Please test and report back results here, by March 3rd 2010 (2010-03-03) or sooner. Upon successful verification of this request, post your results and update the Verified field in Bugzilla with the appropriate value. If you encounter any issues while testing, please describe them and set this bug into NEED_INFO. If you encounter new defects or have additional patch(es) to request for inclusion, please clone this bug per each request and escalate through your support representative. Verified in 2.6.18-182.el5: [root@pe1950-5 ~]# uname -r 2.6.18-182.el5 [root@pe1950-5 ~]# echo 2048 > /sys/block/sda/queue/read_ahead_kb [root@pe1950-5 ~]# cat /sys/block/sda/queue/read_ahead_kb 2048 [root@pe1950-5 ~]# blockdev --setra 4096 /dev/sda [root@pe1950-5 ~]# cat /sys/block/sda/queue/read_ahead_kb 2048 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-2010-0178.html |
Description of problem: RHEL5 inherited a bug from upstream that applies more restrictive checks to the setting of a device's read_ahead_kb parameter when setting the parameter via sysfs instead of via the BLKRASET ioctl: commit da20a20f3b5c175648fa797c899dd577e4dacb51 Author: Jens Axboe <axboe> Date: Fri Jul 21 20:30:28 2006 +0200 [PATCH] ll_rw_blk: allow more flexibility for read_ahead_kb store It can make sense to set read-ahead larger than a single request. We should not be enforcing such policy on the user. Additionally, using the BLKRASET ioctl doesn't impose such a restriction. So additionally we now expose identical behaviour through the two. Issue also reported by Anton <cbou> Signed-off-by: Jens Axboe <axboe> Version-Release number of selected component (if applicable): 2.6.18-157.el5 How reproducible: 100% Steps to Reproduce: 1. echo 2048 > /sys/block/<dev>/queue/read_ahead_kb 2. cat /sys/block/<dev>/queue/read_ahead_kb 3. blockdev --setra 4096 /dev/<dev> 4. cat /sys/block/<dev>/queue/read_ahead_kb Actual results: # echo 2048 > /sys/block/sda/queue/read_ahead_kb # cat /sys/block/sda/queue/read_ahead_kb 512 # blockdev --setra 4096 /dev/sda # cat /sys/block/sda/queue/read_ahead_kb 2048 Expected results: # echo 2048 > /sys/block/sda/queue/read_ahead_kb # cat /sys/block/sda/queue/read_ahead_kb 2048 # blockdev --setra 4096 /dev/sda # cat /sys/block/sda/queue/read_ahead_kb 2048 Additional info: