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From: "fweimer at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug string/27457] vzeroupper use in AVX2 multiarch string functions cause HTM aborts
Date: Mon, 01 Mar 2021 11:32:28 +0000 [thread overview]
Message-ID: <bug-27457-131-xlB8w8JaJR@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-27457-131@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=27457
--- Comment #6 from Florian Weimer <fweimer at redhat dot com> ---
(In reply to H.J. Lu from comment #5)
> I added another set of AVX/AVX2 functions to support RTM. You can use
> libcpu-rt-c.so:
>
> https://gitlab.com/cpu-rt/glibc/-/wikis/libcpu-rt-c.so-to-avoid-vzeroupper-
> in-RTM-region
>
> to try it out.
The sources do not seem to show the selection logic.
__memset_avx2_unaligned_rtm seems to simply have dropped the VZEROUPPER
instruction, which can't be good for general application performance.
Anyway, is there anything we can realistically do here on CPUs with AVX2, but
without AVX-512? VPXOR doesn't avoid the transition penalty according to the
Intel documentation. Switching to 128-bit registers once the CPU supports RTM
is also likely to introduce performance regressions in non-transactional code.
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next prev parent reply other threads:[~2021-03-01 11:32 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 12:40 [Bug string/27457] New: " rguenth at gcc dot gnu.org
2021-02-22 12:40 ` [Bug string/27457] " rguenth at gcc dot gnu.org
2021-02-22 14:50 ` matz at suse dot de
2021-02-22 15:00 ` rguenth at gcc dot gnu.org
2021-02-22 15:26 ` hjl.tools at gmail dot com
2021-02-22 15:26 ` hjl.tools at gmail dot com
2021-02-22 18:45 ` fweimer at redhat dot com
2021-02-23 9:44 ` roman.dementiev at intel dot com
2021-02-27 2:39 ` hjl.tools at gmail dot com
2021-02-27 7:34 ` rguenther at suse dot de
2021-02-28 14:53 ` hjl.tools at gmail dot com
2021-03-01 11:32 ` fweimer at redhat dot com [this message]
2021-03-01 12:24 ` mliska at suse dot cz
2021-03-01 12:47 ` rguenther at suse dot de
2021-03-01 13:13 ` roman.dementiev at intel dot com
2021-03-01 13:19 ` fweimer at redhat dot com
2021-03-01 13:21 ` hjl.tools at gmail dot com
2021-03-01 13:24 ` hjl.tools at gmail dot com
2021-03-01 13:27 ` hjl.tools at gmail dot com
2021-03-01 13:29 ` hjl.tools at gmail dot com
2021-03-01 13:44 ` rguenth at gcc dot gnu.org
2021-03-01 14:05 ` hjl.tools at gmail dot com
2021-03-01 14:14 ` rguenther at suse dot de
2021-03-01 14:25 ` rguenth at gcc dot gnu.org
2021-03-01 14:37 ` hjl.tools at gmail dot com
2021-03-01 14:47 ` hjl.tools at gmail dot com
2021-03-01 14:49 ` rguenth at gcc dot gnu.org
2021-03-01 14:53 ` rguenth at gcc dot gnu.org
2021-03-01 15:19 ` hjl.tools at gmail dot com
2021-03-01 23:39 ` hjl.tools at gmail dot com
2021-03-05 16:54 ` hjl.tools at gmail dot com
2021-03-11 10:42 ` rguenth at gcc dot gnu.org
2021-03-16 13:53 ` rguenth at gcc dot gnu.org
2021-03-16 14:12 ` hjl.tools at gmail dot com
2021-03-29 23:00 ` hjl.tools at gmail dot com
2022-01-27 20:21 ` cvs-commit at gcc dot gnu.org
2022-01-27 20:23 ` cvs-commit at gcc dot gnu.org
2022-01-27 20:47 ` cvs-commit at gcc dot gnu.org
2022-01-27 20:47 ` cvs-commit at gcc dot gnu.org
2022-01-27 20:48 ` cvs-commit at gcc dot gnu.org
2022-01-27 22:41 ` cvs-commit at gcc dot gnu.org
2022-01-28 2:24 ` hjl.tools at gmail dot com
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