From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Yong Zhang <yong.zhang0@gmail.com>
Cc: Venki Pallipadi <venki@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Aaron Durbin <adurbin@google.com>, Paul Turner <pjt@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Extend mwait idle to optimize away CAL and RES interrupts to an idle CPU -v1
Date: Mon, 27 Feb 2012 09:05:27 -0800 [thread overview]
Message-ID: <20120227170527.GD2463@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120227090646.GA1112@zhy>
On Mon, Feb 27, 2012 at 05:06:46PM +0800, Yong Zhang wrote:
> On Sat, Feb 25, 2012 at 05:32:53PM -0800, Paul E. McKenney wrote:
> > On Fri, Feb 24, 2012 at 01:41:50PM +0800, Yong Zhang wrote:
> > > On Thu, Feb 23, 2012 at 11:34:11AM -0800, Venki Pallipadi wrote:
> > > > On Thu, Feb 23, 2012 at 1:30 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > > > > Why not scheduler_ipi()?
> > > >
> > > > Was trying to avoid irq_enter/exit. As the work here is done in idle
> > > > thread context, I though we could avoid enter/exit.
> > >
> > > It seems we could not.
> > > At least RCU need it, see commit c5d753a55, otherwise we will get
> > > warning like 'RCU used illegally from extended quiescent state!'
> >
> > If the use is tracing, then Steven Rostedt's patchset plus use of his
> > _rcuidle() tracing variants handles this:
> >
> > https://lkml.org/lkml/2012/2/7/231
> >
> > If this is instead algorithmic use of RCU, a set of patches I have queued
> > up for 3.4 will be required.
>
> scheduler_ipi() doing more than tracing. Will look at your patches :)
Ah! The key question is whether or not the code in question is called
both from idle and from non-idle. This will be easiest if the code is
called only from idle, in which case you should only need this one:
https://lkml.org/lkml/2012/2/3/498
Thanx, Paul
next prev parent reply other threads:[~2012-02-27 17:09 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-23 0:36 [PATCH] Extend mwait idle to optimize away CAL and RES interrupts to an idle CPU -v1 Venkatesh Pallipadi
2012-02-23 7:50 ` Ingo Molnar
2012-02-23 9:08 ` Peter Zijlstra
2012-02-23 20:04 ` Venki Pallipadi
2012-02-23 20:03 ` Venki Pallipadi
2012-03-02 0:33 ` Venki Pallipadi
2012-03-02 1:28 ` Suresh Siddha
2012-03-02 1:35 ` Venki Pallipadi
2012-03-02 1:37 ` Suresh Siddha
2012-03-02 2:00 ` Venki Pallipadi
2012-03-02 7:21 ` Ingo Molnar
2012-03-02 17:41 ` Suresh Siddha
2012-03-06 21:41 ` fork_idle from wq cleanup Venkatesh Pallipadi
2012-03-06 21:41 ` [PATCH 1/5] x86: Move fork_idle from wq and idle caching to common code Venkatesh Pallipadi
2012-03-06 21:41 ` [PATCH 2/5] ia64: Use common fork_idle_from_wq in smpboot Venkatesh Pallipadi
2012-03-06 21:41 ` [PATCH 3/5] mips: " Venkatesh Pallipadi
2012-03-06 22:51 ` Ralf Baechle
2012-03-06 21:41 ` [PATCH 4/5] powerpc: " Venkatesh Pallipadi
2012-03-06 21:41 ` [PATCH 5/5] s390: " Venkatesh Pallipadi
2012-03-07 7:00 ` Heiko Carstens
2012-03-07 6:06 ` fork_idle from wq cleanup Suresh Siddha
2012-02-23 9:30 ` [PATCH] Extend mwait idle to optimize away CAL and RES interrupts to an idle CPU -v1 Peter Zijlstra
2012-02-23 19:34 ` Venki Pallipadi
2012-02-24 5:41 ` Yong Zhang
2012-02-24 6:13 ` Yong Zhang
2012-02-27 8:38 ` Peter Zijlstra
2012-02-27 9:08 ` Yong Zhang
2012-02-27 9:30 ` Peter Zijlstra
2012-02-27 9:51 ` Yong Zhang
2012-02-26 1:32 ` Paul E. McKenney
2012-02-27 9:06 ` Yong Zhang
2012-02-27 17:05 ` Paul E. McKenney [this message]
2012-02-28 7:12 ` Yong Zhang
2012-02-28 13:05 ` Paul E. McKenney
2012-02-29 6:36 ` Yong Zhang
2012-02-27 8:45 ` Peter Zijlstra
2012-02-27 18:17 ` Venki Pallipadi
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