From: Peter Zijlstra <peterz@infradead.org>
To: Venki Pallipadi <venki@google.com>
Cc: 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>,
Yong Zhang <yong.zhang0@gmail.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 09:45:54 +0100 [thread overview]
Message-ID: <1330332354.11248.32.camel@twins> (raw)
In-Reply-To: <CABeCy1a0U8Hk3Yfp54M-U80t2fbPrFQw=GnNQ_V082e9VxJQow@mail.gmail.com>
On Thu, 2012-02-23 at 11:34 -0800, Venki Pallipadi wrote:
> > > + local_bh_disable();
> > > + local_irq_disable();
> >
> > That local_bh_disable() is completely superfluous, disabling IRQs
> > already kills bh.
>
> The reason for local_bh_disable/enable was to check for potential
> softirqs after these interrupt.
Why is that needed? We never wrap local_irq_disable() in bh muck?
> > Why doesn't ipiless_idle_exit() call this? That would keep it isolated
> > to just those idle routines that actually use mwait instead of bothering
> > the generic idle paths with this.
>
> ipiless_idle_exit is called in the inner most part of idle entry exit.
> In mwait case we may not even have interrupts enabled at that time and
> there is code that does idle residency timing etc which will get
> impacted if we start doing the pending ipi work there. Doing it at
> higher level along with things like enter-exit tickless felt nicer.
But but but, an actual interrupt can be handled before the instruction
after mwait, so why would this be a problem?
next prev parent reply other threads:[~2012-02-27 8:46 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
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 [this message]
2012-02-27 18:17 ` Venki Pallipadi
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