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From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Mike Galbraith <bitbucket@online.de>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>, Len Brown <lenb@kernel.org>,
	Linux PM list <linux-pm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Jeremy Eder <jeder@redhat.com>,
	x86@kernel.org
Subject: Re: 50 Watt idle power regression bisected to Linux-3.10
Date: Wed, 11 Dec 2013 17:44:03 +0100	[thread overview]
Message-ID: <20131211164403.GB2480@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <20131211144238.GA4510@gmail.com>

On Wed, Dec 11, 2013 at 03:42:38PM +0100, Ingo Molnar wrote:
> Another thing that is required I think is to issue a write barrier 
> before CLFLUSH instruction. By my (possibly incorrect ...) reading of 
> the documentation CLFLUSH does not appear to be ordered (at all), so 
> it might execute before the modification to the affected memory?
> 
> 
> So something like:
> 
> 		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) {
> 			smp_wmb(); /* order CLFLUSH */
> 			clflush(&current_thread_info()->flags);
> 		}

smp_wmb() is a NO-OP on x86 remember :-)

Also, a wmb doesn't actually need to flush the store buffers.

  parent reply	other threads:[~2013-12-11 16:44 UTC|newest]

Thread overview: 51+ 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 [this message]
2013-12-11 17:47                             ` Ingo Molnar
2013-12-11 21:43                     ` Len Brown
2013-12-11 22:22                       ` Thomas Gleixner

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