Bug 1323294
| Summary: | AVX-2 migration optimisation | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 7 | Reporter: | Dr. David Alan Gilbert <dgilbert> |
| Component: | qemu-kvm-rhev | Assignee: | Dr. David Alan Gilbert <dgilbert> |
| Status: | CLOSED ERRATA | QA Contact: | Guo, Zhiyi <zhguo> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | 7.3 | CC: | amit.shah, chayang, dgilbert, huding, juzhang, knoel, mrezanin, qizhu, virt-maint, xfu, zhguo |
| Target Milestone: | rc | Keywords: | TestOnly |
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | qemu-kvm-rhev-2.6.0-8.el7 | Doc Type: | Bug Fix |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2016-11-07 21:03:57 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: | |||
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Comment 2
Amit Shah
2016-04-05 06:13:38 UTC
(In reply to Amit Shah from comment #2) > AVX2 is already supported in Broadwell and Haswell, we should be able to > test it. > > Note that avx2 support was added, not avx-512. So maybe the summary should > be updated? Yep, you're right, so we should be able to test it on an AVX2 machine which we'll have somewhere. (In reply to Dr. David Alan Gilbert from comment #3) > (In reply to Amit Shah from comment #2) > > AVX2 is already supported in Broadwell and Haswell, we should be able to > > test it. > > > > Note that avx2 support was added, not avx-512. So maybe the summary should > > be updated? > > Yep, you're right, so we should be able to test it on an AVX2 machine which > we'll have somewhere. "grep avx2 /proc/cpuinfo" will confirm if the machine has the extensions which this feature uses. OK, it looks like we have two problems: a) the configure time test gets optimised out with -O2 and decides it can't do AVX2 b) There's a compile time test in the code that uses it which checks that it has gcc4.9 or better to work around a header bug, but we've only get 4.8.5 in RHEL. Paolo says that's due to https://gcc.gnu.org/ml/gcc-patches/2013-06/txt6Tt74laQsp.txt which we don't seem to have yet. Fix included in qemu-kvm-rhev-2.6.0-8.el7 Move to verified per comment 13 & 14 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. https://rhn.redhat.com/errata/RHBA-2016-2673.html |