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From: Ingo Molnar <mingo@kernel.org>
To: Daniel J Blueman <daniel@numascale.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Rafael David Tinoco <inaddy@ubuntu.com>,
	Peter Anvin <hpa@zytor.com>,
	Jiang Liu <jiang.liu@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Gema Gomez <gema.gomez-solano@canonical.com>,
	Christopher Arges <chris.j.arges@canonical.com>,
	the arch/x86 maintainers <x86@kernel.org>
Subject: Re: smp_call_function_single lockups
Date: Sun, 22 Feb 2015 11:37:09 +0100	[thread overview]
Message-ID: <20150222103709.GA24818@gmail.com> (raw)
In-Reply-To: <54E99A8F.1080803@numascale.com>


* Daniel J Blueman <daniel@numascale.com> wrote:

> The Intel SDM [1] and AMD F15h BKDG [2] state that IPIs 
> are queued, so the wait_icr_idle() polling is only 
> necessary on PPro and older, and maybe then to avoid 
> delivery retry. This unnecessarily ties up the IPI 
> caller, so we bypass the polling in the Numachip APIC 
> driver IPI-to-self path.

It would be nice to propagate this back to the generic x86 
code.

> On Linus's earlier point, with the large core counts on 
> Numascale systems, I previously implemented a shortcut to 
> allow single IPIs to bypass all the cpumask generation 
> and walking; it's way down on my list, but I'll see if I 
> can generalise and present a patch series at some point 
> if interested?

I am definitely interested!

Thanks,

	Ingo

  reply	other threads:[~2015-02-22 10:37 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-22  8:59 smp_call_function_single lockups Daniel J Blueman
2015-02-22 10:37 ` Ingo Molnar [this message]
  -- strict thread matches above, loose matches on Subject: below --
2015-02-11 13:19 Rafael David Tinoco
2015-02-11 18:18 ` Linus Torvalds
2015-02-11 19:59   ` Linus Torvalds
2015-02-11 20:42     ` Linus Torvalds
2015-02-12 16:38       ` Rafael David Tinoco
2015-02-18 22:25       ` Peter Zijlstra
2015-02-19 15:42         ` Rafael David Tinoco
2015-02-19 16:14           ` Linus Torvalds
2015-02-23 14:01             ` Rafael David Tinoco
2015-02-23 19:32               ` Linus Torvalds
2015-02-23 20:50                 ` Peter Zijlstra
2015-02-23 21:02                   ` Rafael David Tinoco
2015-02-19 16:16           ` Peter Zijlstra
2015-02-19 16:26           ` Linus Torvalds
2015-02-19 16:32             ` Rafael David Tinoco
2015-02-19 16:59               ` Linus Torvalds
2015-02-19 17:30                 ` Rafael David Tinoco
2015-02-19 17:39                 ` Linus Torvalds
2015-02-19 20:29                   ` Linus Torvalds
2015-02-19 21:59                     ` Linus Torvalds
2015-02-19 22:45                       ` Linus Torvalds
2015-03-31  3:15                         ` Chris J Arges
2015-03-31  4:28                           ` Linus Torvalds
2015-03-31  4:46                           ` Linus Torvalds
2015-03-31 15:08                           ` Linus Torvalds
2015-03-31 22:23                             ` Chris J Arges
2015-03-31 23:07                               ` Linus Torvalds
2015-04-01 14:32                                 ` Chris J Arges
2015-04-01 15:36                                   ` Linus Torvalds
2015-04-02  9:55                                     ` Ingo Molnar
2015-04-02 17:35                                       ` Linus Torvalds
2015-04-01 12:43                               ` Ingo Molnar
2015-04-01 16:10                                 ` Chris J Arges
2015-04-01 16:14                                   ` Linus Torvalds
2015-04-01 21:59                                     ` Chris J Arges
2015-04-02 17:31                                       ` Linus Torvalds
2015-04-02 18:26                                         ` Ingo Molnar
2015-04-02 18:51                                           ` Chris J Arges
2015-04-02 19:07                                             ` Ingo Molnar
2015-04-02 20:57                                               ` Linus Torvalds
2015-04-02 21:13                                               ` Chris J Arges
2015-04-03  5:45                                                 ` Ingo Molnar
2015-04-06 17:23                                         ` Chris J Arges
2015-02-20  9:30                     ` Ingo Molnar
2015-02-20 16:49                       ` Linus Torvalds
2015-02-20 19:41                         ` Ingo Molnar
2015-02-20 20:03                           ` Linus Torvalds
2015-02-20 20:11                             ` Ingo Molnar
2015-03-20 10:15       ` Peter Zijlstra
2015-03-20 16:26         ` Linus Torvalds
2015-03-20 17:14           ` Mike Galbraith
2015-04-01 14:22       ` Frederic Weisbecker

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