Bug 390451
| Summary: | Pick up paging performance improvements from upstream Xen | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 5 | Reporter: | Stephen Tweedie <sct> | ||||
| Component: | kernel-xen | Assignee: | Paolo Bonzini <pbonzini> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> | ||||
| Severity: | low | Docs Contact: | |||||
| Priority: | low | ||||||
| Version: | 5.1 | CC: | clalance, drjones, jzheng, k.georgiou, kkolakow, qcai, xen-maint, yuzhang | ||||
| Target Milestone: | --- | ||||||
| Target Release: | --- | ||||||
| Hardware: | All | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2011-07-21 10:27:51 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: | 514490, 648851 | ||||||
| Attachments: |
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Missed the boat for RHEL 5.2, flaged to look at for 5.3. 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. Created attachment 465972 [details]
pte_clear patch
I think backporting the whole series is pretty much out of question at this point.
However, if the pte_clear hunk is really that effective, it may be worthwhile to benchmark it.
Measured 2-3% improvement on a 2 VCPU RHEL5 32-bit guest running on 64-bit host 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. Patch(es) available in kernel-2.6.18-248.el5 Detailed testing feedback is always welcomed. 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-2011-1065.html |
Upstream Xen-3.1 contains the following in changeset 14731: > # HG changeset patch > # User kfraser > # Date 1175760633 -3600 > # Node ID 14c25e48a55730115c71e592ae065e715c1d23af > # Parent 07d3208c0ca3b6e746745d2bc08f7aa12ed39269 > linux: improve x86 page table handling performance > > Where possible, > - use hypercalls instead of writing to read-only pages > - fold TLB flushes into page table update hypercalls > - on PAE, use single-access updates instead of two-access ones > > The single change to PAE pte_clear() yields a 25-30% boost for kernel > builds on a 4x2x2 CPUs, 8Gb box; the other changes together yield > improvements of 2-5%. Note that it also needs the bugfixes from upstream linux-2.6.18-xen.hg's csets 265 and 266. Given the magnitude of the performance improvement quoted, we should at least evaluate this for 5.2.