From: Anton Blanchard <anton@samba.org>
To: Linus Torvalds <torvalds@osdl.org>
Cc: William Lee Irwin III <wli@holomorphy.com>,
Paul Mackerras <paulus@samba.org>,
Zwane Mwaikambo <zwane@linuxpower.ca>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>, Matt Mackall <mpm@selenic.com>,
"Nakajima, Jun" <jun.nakajima@intel.com>
Subject: Re: [PATCH][5/8] Arch agnostic completely out of line locks / ppc64
Date: Fri, 10 Sep 2004 10:35:05 +1000 [thread overview]
Message-ID: <20040910003505.GG11358@krispykreme> (raw)
In-Reply-To: <Pine.LNX.4.58.0409091712270.5912@ppc970.osdl.org>
Hi,
> Why do we care about profile_pc() here? It should do the right thing
> as-is.
With preempt off profile_pc works as expected, timer ticks in spinlocks
are apportioned to the calling function. Turn preempt on and you end up
with one big bucket called __preempt_spin_lock where most of the
spinlock ticks end up.
> What you care about is wchan, and stack unwiding _over_ the spinlocks.
> Since a spinlock can never be part of the wchan callchain, I vote we just
> change "in_sched_functions()" to claim that anything in the spinlock
> section is also a scheduler function as far as it's concerned.
>
> That makes wchan happy, and profile_pc() really never should care.
At the moment profile_pc is simple and only looks at the timer interrupt
pt_regs. With 2 levels of locks (_spin_lock -> __preempt_spin_lock) we
now have to walk the stack. Obviously fixable, it just a bit more work
in profile_pc. We would also need to move __preempt_spin_lock into the
lock section which should be fine if we change wchan backtracing to do
as you suggest.
Anton
next prev parent reply other threads:[~2004-09-10 0:38 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-03 0:02 [PATCH][5/8] Arch agnostic completely out of line locks / ppc64 Zwane Mwaikambo
2004-09-09 5:42 ` Paul Mackerras
2004-09-09 12:41 ` Zwane Mwaikambo
2004-09-09 14:54 ` Linus Torvalds
2004-09-09 14:55 ` Linus Torvalds
2004-09-09 15:32 ` Zwane Mwaikambo
2004-09-12 4:59 ` [PATCH] Yielding processor resources during lock contention Zwane Mwaikambo
2004-09-12 5:00 ` Andrew Morton
2004-09-12 5:10 ` Anton Blanchard
2004-09-12 5:13 ` Zwane Mwaikambo
2004-09-12 4:32 ` Nick Piggin
2004-09-12 5:33 ` Zwane Mwaikambo
2004-09-12 4:46 ` Nick Piggin
2004-09-12 5:51 ` Zwane Mwaikambo
2004-09-12 5:02 ` Nick Piggin
2004-09-12 6:09 ` Anton Blanchard
2004-09-12 6:58 ` William Lee Irwin III
2004-09-12 5:18 ` Andrew Morton
2004-09-12 5:10 ` Linus Torvalds
2004-09-12 5:27 ` Zwane Mwaikambo
2004-09-13 12:21 ` [PATCH] Yielding processor resources during lock contention #2 Zwane Mwaikambo
2004-09-12 7:49 ` [PATCH] Yielding processor resources during lock contention Ingo Molnar
2004-09-12 16:10 ` Zwane Mwaikambo
2004-09-12 19:34 ` Ingo Molnar
2004-09-12 10:10 ` Arnd Bergmann
2004-09-12 10:43 ` Anton Blanchard
2004-09-12 11:12 ` Arnd Bergmann
2004-09-09 15:43 ` [PATCH][5/8] Arch agnostic completely out of line locks / ppc64 Anton Blanchard
2004-09-09 17:19 ` William Lee Irwin III
2004-09-09 21:38 ` Paul Mackerras
2004-09-09 22:00 ` William Lee Irwin III
2004-09-09 23:36 ` Paul Mackerras
2004-09-10 0:09 ` William Lee Irwin III
2004-09-10 0:21 ` Linus Torvalds
2004-09-10 0:35 ` Anton Blanchard [this message]
2004-09-10 0:54 ` Linus Torvalds
2004-09-10 1:42 ` Anton Blanchard
2004-09-10 1:50 ` Anton Blanchard
2004-09-10 2:22 ` William Lee Irwin III
2004-09-10 2:32 ` William Lee Irwin III
2004-09-10 2:37 ` William Lee Irwin III
2004-09-10 3:24 ` Anton Blanchard
2004-09-10 7:40 ` Ingo Molnar
2004-09-10 12:16 ` William Lee Irwin III
2004-09-10 12:22 ` Ingo Molnar
2004-09-10 3:23 ` Anton Blanchard
2004-09-10 7:56 ` Anton Blanchard
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