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Bug 1022548

Summary: Read/Randread/Randrw performance regression
Product: Red Hat Enterprise Linux 6 Reporter: Xiaomei Gao <xigao>
Component: qemu-kvmAssignee: Fam Zheng <famz>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: urgent Docs Contact:
Priority: urgent    
Version: 6.5CC: areis, bsarathy, famz, juzhang, kwolf, michen, mkenneth, mrezanin, qzhang, rbalakri, stefanha, virt-maint, wquan, xigao
Target Milestone: rcKeywords: Regression, ZStream
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: qemu-kvm-0.12.1.2-2.417.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 1025138 (view as bug list) Environment:
Last Closed: 2014-10-14 06:53:31 UTC Type: Bug
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: 1025138, 1025596    

Comment 4 Kevin Wolf 2013-10-25 07:08:23 UTC
Can you track the regression down to a specific build or smaller set of builds?

Comment 5 Quan Wenli 2013-10-25 08:33:14 UTC
(In reply to Kevin Wolf from comment #4)
> Can you track the regression down to a specific build or smaller set of
> builds?

Kevin, commment #0 has mentioned that this regression was introduced by following patch from qemu-kvm-0.12.1.2-2.391.el6.
 - kvm-block-Produce-zeros-when-protocols-reading-beyond-en.patch [bz#848070]

Comment 6 Xiaomei Gao 2013-10-25 12:34:41 UTC
Btw, kvm_exits frequency is much higher compared to old version on virtio_scsi driver in read/randread/randrw category. Besides, we can also see the issue on local format image with virtio_scsi driver in randrw category, but IOPS does not degrades on local raw format image. Through bisect analysis, we found the high kvm_exits frequency on virtio_scsi driver is also introduced by the patch in comment #5

Comment 8 Xiaomei Gao 2013-10-29 08:44:44 UTC
We could see a little performance degradation in randrw category on local format image. Besides, kvm_exits frequency is much higher on virtio_scsi driver in randrw category. Through bisect analysis, they are both introduced by the patch in comment #5, so i changed the title.

Comment 15 Ademar Reis 2013-11-09 00:47:22 UTC
QE found issues with the fix while testing Bug 1025596 (z-stream clone of this one) and we need additional patches. Moving it back to assigned, Fam is taking care of it.

Comment 16 Qunfang Zhang 2013-11-13 03:20:24 UTC
Hi, Fam

As we already have bug 1025596 to track the z-stream build, so if I understand correctly, this one is for 6.6 and we should have a rhel6.6 build (like -416) in the "Fixed In Version". :) correct me if I'm wrong. 

Thanks a lot for your tracking up on this issue so that QE could have a fixed build earlier to test!

Qunfang

Comment 17 Fam Zheng 2013-11-13 03:41:01 UTC
(In reply to Qunfang Zhang from comment #16)
> Hi, Fam
> 
> As we already have bug 1025596 to track the z-stream build, so if I
> understand correctly, this one is for 6.6 and we should have a rhel6.6 build
> (like -416) in the "Fixed In Version". :) correct me if I'm wrong. 
> 
> Thanks a lot for your tracking up on this issue so that QE could have a
> fixed build earlier to test!
> 

Yes you are right. The status was a mistake.

Moving back to POST.

Fam

Comment 21 errata-xmlrpc 2014-10-14 06:53:31 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2014-1490.html