From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: hpa@zytor.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, tglx@linutronix.de,
hpa@linux.intel.com, len.brown@intel.com,
linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/idle] x86, idle: Use static_cpu_has() for CLFLUSH workaround, add barriers
Date: Thu, 19 Dec 2013 22:55:41 +0100 [thread overview]
Message-ID: <20131219215541.GS16438@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <20131219204051.GA2253@gmail.com>
On Thu, Dec 19, 2013 at 09:40:51PM +0100, Ingo Molnar wrote:
> > + if (static_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) {
> > + mb();
> > clflush((void *)¤t_thread_info()->flags);
> > + mb();
> > + }
> if (!current_set_polling_and_test()) {
> if (static_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) {
> - mb();
> + /*
> + * There's no need for an extra barrier here: current_set_polling_and_test()
> + * already has an smp_mb() after ->flags gets modified, see sched.h.
> + */
> clflush((void *)¤t_thread_info()->flags);
> mb();
> }
So almost, except that smp_mb() will disappear on an UP kernel whereas
this errata might just always need the MFENCE.
Then again, you'd be a pretty big nutter to run an UP kernel on an EX
part.
next prev parent reply other threads:[~2013-12-19 21:55 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-07 8:00 50 Watt idle power regression bisected to Linux-3.10 Len Brown
2013-12-07 8:39 ` Mike Galbraith
2013-12-07 16:01 ` Len Brown
2013-12-07 16:45 ` Len Brown
2013-12-07 19:17 ` Mike Galbraith
2013-12-10 11:41 ` Ingo Molnar
2013-12-07 12:54 ` Thomas Gleixner
2013-12-08 4:57 ` Mike Galbraith
2013-12-08 20:40 ` Len Brown
2013-12-09 3:16 ` Mike Galbraith
2013-12-10 5:17 ` Mike Galbraith
2013-12-10 11:45 ` Ingo Molnar
2013-12-10 14:29 ` Thomas Gleixner
2013-12-10 15:06 ` Ingo Molnar
2013-12-11 2:05 ` Thomas Gleixner
2013-12-11 3:21 ` Mike Galbraith
2013-12-11 11:28 ` Thomas Gleixner
2013-12-11 11:38 ` Borislav Petkov
2013-12-11 11:52 ` Peter Zijlstra
2013-12-11 12:29 ` Mike Galbraith
2013-12-11 12:43 ` Peter Zijlstra
2013-12-11 13:10 ` Mike Galbraith
2013-12-11 13:40 ` Borislav Petkov
2013-12-11 14:56 ` Ingo Molnar
2013-12-11 16:02 ` Borislav Petkov
2013-12-11 16:43 ` Peter Zijlstra
2013-12-11 17:50 ` Ingo Molnar
2013-12-11 23:08 ` H. Peter Anvin
2013-12-11 23:14 ` Borislav Petkov
2013-12-12 0:52 ` H. Peter Anvin
2013-12-12 4:25 ` Mike Galbraith
2013-12-12 4:49 ` H. Peter Anvin
2013-12-12 4:59 ` Mike Galbraith
2013-12-12 5:37 ` Mike Galbraith
2013-12-12 5:45 ` H. Peter Anvin
2013-12-12 5:57 ` Mike Galbraith
2013-12-12 6:05 ` Mike Galbraith
2013-12-12 7:57 ` H. Peter Anvin
2013-12-12 8:51 ` Peter Zijlstra
2013-12-12 13:28 ` Ingo Molnar
2013-12-12 15:06 ` H. Peter Anvin
2013-12-12 15:51 ` Peter Zijlstra
2013-12-11 14:42 ` Ingo Molnar
2013-12-11 15:02 ` Thomas Gleixner
2013-12-11 15:09 ` Ingo Molnar
2013-12-11 16:44 ` Peter Zijlstra
2013-12-11 17:48 ` Ingo Molnar
2013-12-11 16:44 ` Peter Zijlstra
2013-12-11 17:47 ` Ingo Molnar
2013-12-11 21:43 ` Len Brown
2013-12-11 22:22 ` Thomas Gleixner
2013-12-18 21:44 ` [PATCH] x86 idle: repair large-server 50-watt idle-power regression Len Brown
2013-12-18 21:44 ` Len Brown
2013-12-19 12:22 ` Ingo Molnar
2013-12-19 14:40 ` H. Peter Anvin
2013-12-19 15:45 ` Borislav Petkov
2013-12-19 15:55 ` H. Peter Anvin
2013-12-19 16:02 ` Ingo Molnar
2013-12-19 16:09 ` H. Peter Anvin
2013-12-19 16:13 ` H. Peter Anvin
2013-12-19 16:21 ` Peter Zijlstra
2013-12-19 16:50 ` H. Peter Anvin
2013-12-19 17:07 ` Ingo Molnar
2013-12-19 17:25 ` Peter Zijlstra
2013-12-19 17:36 ` Peter Zijlstra
2013-12-19 18:05 ` H. Peter Anvin
2013-12-19 18:14 ` Ingo Molnar
2013-12-19 17:50 ` Peter Zijlstra
2013-12-19 18:18 ` Ingo Molnar
2013-12-19 21:05 ` H. Peter Anvin
2013-12-19 21:17 ` Ingo Molnar
2013-12-19 18:10 ` Ingo Molnar
2013-12-19 18:09 ` H. Peter Anvin
2013-12-19 18:19 ` H. Peter Anvin
2013-12-19 18:23 ` Ingo Molnar
[not found] ` <CA+55aFzGxcML7j8CEvQPYzh0W81uVoAAVmGctMOUZ7CZ1yYd2A@mail.gmail.com>
2013-12-19 18:43 ` Ingo Molnar
2013-12-19 18:43 ` Ingo Molnar
2013-12-19 20:09 ` [tip:x86/idle] x86, idle: Use static_cpu_has() for CLFLUSH workaround, add barriers tip-bot for H. Peter Anvin
2013-12-19 20:40 ` Ingo Molnar
2013-12-19 20:46 ` Linus Torvalds
2013-12-19 21:14 ` Ingo Molnar
2013-12-19 21:25 ` Linus Torvalds
2013-12-19 21:55 ` Peter Zijlstra [this message]
2013-12-20 8:47 ` Ingo Molnar
2013-12-19 20:33 ` [tip:x86/idle] x86, idle: Add memory barriers around clflush in mwait_play_dead() tip-bot for H. Peter Anvin
2013-12-19 18:19 ` [PATCH] x86 idle: repair large-server 50-watt idle-power regression Ingo Molnar
2013-12-19 19:22 ` H. Peter Anvin
2013-12-19 19:27 ` Peter Zijlstra
2013-12-19 19:51 ` [tip:x86/urgent] x86 idle: Repair " tip-bot for Len Brown
2014-03-18 0:20 ` Davidlohr Bueso
2014-03-18 9:16 ` Peter Zijlstra
2014-03-19 2:14 ` Jason Low
2014-03-19 6:42 ` Peter Zijlstra
2014-04-08 21:43 ` Brown, Len
2014-04-09 8:18 ` Peter Zijlstra
2014-04-15 3:27 ` Davidlohr Bueso
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131219215541.GS16438@laptop.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=hpa@linux.intel.com \
--cc=hpa@zytor.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.