Bug 712653
| Summary: | make guest mode entry to be rcu quiescent state | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Gleb Natapov <gleb> |
| Component: | kernel | Assignee: | Gleb Natapov <gleb> |
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> |
| Severity: | high | Docs Contact: | |
| Priority: | urgent | ||
| Version: | 6.2 | CC: | cww, dhoward, juzhang, knoel, skito, tburke, tmuneda |
| Target Milestone: | rc | Keywords: | ZStream |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | kernel-2.6.32-160.el6 | Doc Type: | Bug Fix |
| Doc Text: |
When a CPU is about to modify data protected by the RCU (Read Copy Update) mechanism, it has to wait for other CPUs in the system to pass a quiescent state. Previously, the guest mode was not considered a quiescent state. As a consequence, if a CPU was in the guest mode for a long time, another CPU had to wait a long time in order to modify RCU-protected data. With this update, the rcu_virt_note_context_switch() function, which marks the guest mode as a quiescent state, has been added to the kernel, thus resolving this issue.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | 2011-12-06 13:38:43 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: | 740352 | ||
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Description
Gleb Natapov
2011-06-12 07:50:39 UTC
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. Tested on 2.6.32-156.el6.x86_64 with qemu-kvm-0.12.1.2-2.165.el6.x86_64, marked as qa_ack+ steps 1. boot guest with virtio devices and vcpu=4 2. in guest #halt Result: guest just pause for a couple of seconds after printing "Disabling non-boot CPUs" Please note: guest should be rhel6.X Patch(es) available on kernel-2.6.32-160.el6 Verified this issue on kernel 2.6.32-206.el6.x86_64 with qemu-kvm-0.12.1.2-2.195.el6.x86_64.,I tried three times. 1.boot guest with boot guest with virtio devices and vcpu=4 2.in guest #half Results: No pause after printing "Disabling non-boot CPUs" Guest kernel 2.6.32-206.el6.x86_64
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New Contents:
When a CPU is about to modify data protected by the RCU (Read Copy Update) mechanism, it has to wait for other CPUs in the system to pass a quiescent state. Previously, the guest mode was not considered a quiescent state. As a consequence, if a CPU was in the guest mode for a long time, another CPU had to wait a long time in order to modify RCU-protected data. With this update, the rcu_virt_note_context_switch() function, which marks the guest mode as a quiescent state, has been added to the kernel, thus resolving this issue.
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/RHSA-2011-1530.html |