From: Peter Zijlstra <peterz@infradead.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
Mike Galbraith <bitbucket@online.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: Thu, 12 Dec 2013 16:51:53 +0100 [thread overview]
Message-ID: <20131212155153.GK13532@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <52A9D111.3090409@zytor.com>
On Thu, Dec 12, 2013 at 07:06:57AM -0800, H. Peter Anvin wrote:
> On 12/12/2013 05:28 AM, Ingo Molnar wrote:
> >>
> >> The reason we use thread_info::flags is because we need to write
> >> TIF_NEED_RESCHED into it to wake up anyhow.
> >>
> >> Using another cacheline would mean the wakeup path would need to write a
> >> second cross cpu cacheline -- that is badness too.
> >>
> >> So no, I don't think we want to listen to another line.
> >
>
> Right, okay, so that's the implicit wakeup. However, I would think the
> CLFLUSH would hurt a lot more.
Maybe, but still, who cares? Its only a few broken cpus that actually
need the clflush, normal cpus do not. We should not optimize for the
broken case.
next prev parent reply other threads:[~2013-12-12 15:52 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 [this message]
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
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=20131212155153.GK13532@twins.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=bitbucket@online.de \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=jeder@redhat.com \
--cc=lenb@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox