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From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Don Zickus <dzickus@redhat.com>, Andi Kleen <ak@linux.intel.com>,
	dave.hansen@linux.intel.com,
	Stephane Eranian <eranian@google.com>,
	jmario@redhat.com,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Arnaldo Carvalho de Melo <acme@infradead.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip()
Date: Fri, 18 Oct 2013 00:01:56 +0200	[thread overview]
Message-ID: <20131017220156.GB10651@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFx-1Xu2aSvAMi8SSUwq-J9Yo3oJGY8yUYWyAZmZmr8prQ@mail.gmail.com>

On Thu, Oct 17, 2013 at 11:26:23AM -0700, Linus Torvalds wrote:
> On Thu, Oct 17, 2013 at 9:30 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > So avoid having to call copy_from_user_nmi() for every instruction.
> > Since we already limit the max basic block size, we can easily
> > pre-allocate a piece of memory to copy the entire thing into in one
> > go.
> 
> copy_from_user_nmi() itself is all kinds of nasty.

Oh wait,.. now that Steven fixed being able to take faults from NMI
context; we could actually try copy_from_user_inatomic(). Being able to
directly access userspace would make the whole deal a lot easier again.

I'll go try this tomorrow.

  parent reply	other threads:[~2013-10-17 22:02 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-14 20:35 x86, perf: throttling issues with long nmi latencies Don Zickus
2013-10-14 21:28 ` Andi Kleen
2013-10-15 10:14 ` Peter Zijlstra
2013-10-15 13:02   ` Peter Zijlstra
2013-10-15 14:32     ` Peter Zijlstra
2013-10-15 15:07       ` Peter Zijlstra
2013-10-15 15:41         ` Don Zickus
2013-10-16 10:57           ` [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Peter Zijlstra
2013-10-16 12:46             ` Don Zickus
2013-10-16 13:31               ` Peter Zijlstra
2013-10-16 13:54                 ` Don Zickus
2013-10-17 11:21                 ` Peter Zijlstra
2013-10-17 13:33                 ` Peter Zijlstra
2013-10-29 14:07                   ` [tip:perf/urgent] perf/x86: Fix NMI measurements tip-bot for Peter Zijlstra
2013-10-16 20:52             ` [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Andi Kleen
2013-10-16 21:03               ` Peter Zijlstra
2013-10-16 23:07                 ` Peter Zijlstra
2013-10-17  9:41                   ` Peter Zijlstra
2013-10-17 16:00                     ` Don Zickus
2013-10-17 16:04                       ` Don Zickus
2013-10-17 16:30                         ` Peter Zijlstra
2013-10-17 18:26                           ` Linus Torvalds
2013-10-17 21:08                             ` Peter Zijlstra
2013-10-17 21:11                               ` Peter Zijlstra
2013-10-17 22:01                             ` Peter Zijlstra [this message]
2013-10-17 22:27                               ` Linus Torvalds
2013-10-22 21:12                                 ` Peter Zijlstra
2013-10-23  7:09                                   ` Linus Torvalds
2013-10-23 20:48                                     ` Peter Zijlstra
2013-10-24 10:52                                       ` Peter Zijlstra
2013-10-24 13:47                                         ` Don Zickus
2013-10-24 14:06                                           ` Peter Zijlstra
2013-10-25 16:33                                         ` Don Zickus
2013-10-25 17:03                                           ` Peter Zijlstra
2013-10-26 10:36                                           ` Ingo Molnar
2013-10-28 13:19                                             ` Don Zickus
2013-10-29 14:08                                         ` [tip:perf/core] perf/x86: Further optimize copy_from_user_nmi() tip-bot for Peter Zijlstra
2013-10-23  7:44                                   ` [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Ingo Molnar
2013-10-17 14:49             ` Don Zickus
2013-10-17 14:51               ` Peter Zijlstra
2013-10-17 15:03                 ` Don Zickus
2013-10-17 15:09                   ` Peter Zijlstra
2013-10-17 15:11                     ` Peter Zijlstra
2013-10-17 16:50             ` [tip:perf/core] perf/x86: " tip-bot for Peter Zijlstra
2013-10-15 16:22         ` x86, perf: throttling issues with long nmi latencies Don Zickus
2013-10-15 14:36     ` Don Zickus
2013-10-15 14:39       ` Peter Zijlstra

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