Bug 604159
| Summary: | virtio-blk: Avoid zeroing every request structure | ||||||||
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| Product: | Red Hat Enterprise Linux 5 | Reporter: | RHEL Program Management <pm-rhel> | ||||||
| Component: | kvm | Assignee: | Virtualization Maintenance <virt-maint> | ||||||
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> | ||||||
| Severity: | medium | Docs Contact: | |||||||
| Priority: | high | ||||||||
| Version: | 5.6 | CC: | cpelland, ehabkost, gyue, Jes.Sorensen, llim, mjenner, mkenneth, pm-eus, tburke, virt-maint, ykaul | ||||||
| Target Milestone: | rc | Keywords: | ZStream | ||||||
| Target Release: | --- | ||||||||
| Hardware: | All | ||||||||
| OS: | Linux | ||||||||
| Whiteboard: | |||||||||
| Fixed In Version: | kvm-83-164.el5_5.13 | Doc Type: | Bug Fix | ||||||
| Doc Text: |
The virtio-blk back end for qemu-kvm performed unnecessary zeroing of memory on every I/O request, which reduced virtual guest performance. With this update, the virtio-blk back end avoids spurious zeroing of request structures on each I/O request, with the result that guest performance is increased.
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Story Points: | --- | ||||||
| Clone Of: | Environment: | ||||||||
| Last Closed: | 2010-07-29 05:49:59 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: | 598042 | ||||||||
| Bug Blocks: | |||||||||
| Attachments: |
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Description
RHEL Program Management
2010-06-15 14:22:17 UTC
Created attachment 426506 [details]
test result
Created attachment 426846 [details]
test result with raw
Tested in kvm-83-164.el5_5.11 & kvm-83-164.el5_5.13.(#comment5,6,7,8) The performance boost of 7-29% in kvm-83-164.el5_5.13. So this bug fixed. Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: Cause: the virtio-blk backend on qemu-kvm was doing unnecessary zeroing of memory on every I/O request. Consequence: performance impact due to unnecessary memory writes. Fix: avoid zeroing whole requests structures on every I/O requests. Consequence: performance boosts on virtio-blk. Technical note updated. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. Diffed Contents: @@ -1,7 +1 @@ -Cause: the virtio-blk backend on qemu-kvm was doing unnecessary zeroing of memory on every I/O request. +The virtio-blk back end for qemu-kvm performed unnecessary zeroing of memory on every I/O request, which reduced virtual guest performance. With this update, the virtio-blk back end avoids spurious zeroing of request structures on each I/O request, with the result that guest performance is increased.- -Consequence: performance impact due to unnecessary memory writes. - -Fix: avoid zeroing whole requests structures on every I/O requests. - -Consequence: performance boosts on virtio-blk. 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/RHBA-2010-0536.html |