Bug 783950
| Summary: | RFE: Backport corountine-based block layer | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Kevin Wolf <kwolf> |
| Component: | qemu-kvm | Assignee: | Kevin Wolf <kwolf> |
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | 6.3 | CC: | acathrow, areis, bsarathy, juzhang, michen, mkenneth, pbonzini, rhod, shu, tburke, virt-maint, wquan |
| Target Milestone: | rc | Keywords: | FutureFeature |
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | qemu-kvm-0.12.1.2-2.228.el6 | Doc Type: | Enhancement |
| Doc Text: |
Improved access to qcow2 disk images
KVM in Red Hat Enterprise Linux 6.3 improved the access to qcow2 disk images (qcow2 is the default format) by making it more asynchronous, thus avoiding vCPU stalls and enhancing the overall performance during disk I/O.
|
Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | 2012-06-20 11:38:44 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: | 582475, 748534, 748906, 782029, 802284, 806432, 812085, 813953 | ||
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:
qemu-kvm in RHEL6.3 improved the access to qcow2 disk images (qcow2 is the default format) by making it more asynchronous, thus avoiding vCPU stalls and enhancing the overall performance during disk I/O.
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 +1,3 @@
-qemu-kvm in RHEL6.3 improved the access to qcow2 disk images (qcow2 is the default format) by making it more asynchronous, thus avoiding vCPU stalls and enhancing the overall performance during disk I/O.+Improved access to qcow2 disk images
+
+KVM in Red Hat Enterprise Linux 6.3 improved the access to qcow2 disk images (qcow2 is the default format) by making it more asynchronous, thus avoiding vCPU stalls and enhancing the overall performance during disk I/O.
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:
@@ -1,3 +1 @@
-Improved access to qcow2 disk images
+No documentation needed-
-KVM in Red Hat Enterprise Linux 6.3 improved the access to qcow2 disk images (qcow2 is the default format) by making it more asynchronous, thus avoiding vCPU stalls and enhancing the overall performance during disk I/O.
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 +1,5 @@
-No documentation needed+Improved access to qcow2 disk images
+
+KVM in Red Hat Enterprise Linux 6.3 improved the access to qcow2 disk images
+(qcow2 is the default format) by making it more asynchronous, thus avoiding
+vCPU stalls and enhancing the overall performance during disk I/O.
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:
@@ -1,5 +1,3 @@
Improved access to qcow2 disk images
-KVM in Red Hat Enterprise Linux 6.3 improved the access to qcow2 disk images
+KVM in Red Hat Enterprise Linux 6.3 improved the access to qcow2 disk images (qcow2 is the default format) by making it more asynchronous, thus avoiding vCPU stalls and enhancing the overall performance during disk I/O.-(qcow2 is the default format) by making it more asynchronous, thus avoiding
-vCPU stalls and enhancing the overall performance during disk I/O.
Hi,kwolf Since qemu-kvm-278 is the mirroring implementation first merged and qemu-kvm-261 is the image streaming implementation first merged,i could not reproduce this bug through live block copy/image streaming w/ the qemu version prior to -228,Do you have any suggestion to reproduce it? Or is it possible reproduce it w/ qemu which is removed the patchset of backport corountine-based block layer from latest qemu-kvm, if it can, could you build one for me reproduce it? Thanks wenli Coroutine-based block layer is required for streaming and mirroring, so it's not possible to test them without coroutines. This bug is really about a rewrite of some parts of the block layer; even though it does have some visible effects listed in the release notes, it is mostly an enabler for streaming and mirroring. Since qcow2 is already tested by the regular test plan, SanityOnly verification should be enough. (In reply to comment #9) > Coroutine-based block layer is required for streaming and mirroring, so it's > not possible to test them without coroutines. > > This bug is really about a rewrite of some parts of the block layer; even > though it does have some visible effects listed in the release notes, it is > mostly an enabler for streaming and mirroring. Since qcow2 is already tested > by the regular test plan, SanityOnly verification should be enough. Thanks Paolo. I verified it w/ qemu-kvm-rhev-290,through monitor jitter by "./jitterd -f -m 2 -p 100 -r 10" on the guest while streaming,there is no chatter greater than 200 millisecond(s).So,I change it to verified. 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-2012-0746.html |
Features like live block copy/image streaming make heavy use of the coroutine-based block layer infrastructure in upstream qemu. We need to backport the whole infrastructure before we can make use of it in new features. As a side effect, this fixes the bug that image formats like qcow2 block the VCPU during I/O requests. The problem can be reproduced with jitterd, which reports problems on the current RHEL package, but doesn't any more when the coroutine patches are applied: * http://git.codemonkey.ws/cgit/jitterd.git/ * Options used in earlier testing: ./jitterd -f -m 2 -p 100 -r 10