From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: Sasha Levin <levinsasha928@gmail.com>,
Pekka Enberg <penberg@kernel.org>,
Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>,
kvm@vger.kernel.org, asias.hejun@gmail.com, gorcunov@gmail.com,
prasadjoshi124@gmail.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
takuya.yoshikawa@gmail.com
Subject: Re: [PATCH v2 6/8] kvm tools: Add rwlock wrapper
Date: Mon, 30 May 2011 21:32:53 +0200 [thread overview]
Message-ID: <20110530193253.GA5707@elte.hu> (raw)
In-Reply-To: <4DE3AED3.7070405@redhat.com>
* Avi Kivity <avi@redhat.com> wrote:
> > Also, a profile of a typical kernel build shows:
> >
> > 0.69% cc1 [kernel.kallsyms] [k] clear_page_c
> > 0.49% cc1 [kernel.kallsyms] [k] page_fault
> >
> > So while we could improve it, the question is, can we do this without
> > accidentally slowing things down by more than 0.69%? And kernel
> > builds are a pretty clear_page_c() intense workload.
>
> I usually see much higher clear_page_c, but I'm using a pretty old
> system for most of my testing.
Well, clear_page_c() is still the most expensive kernel function.
I'd suggest using a modern system *and* using percise PEBS profiling
via perf record -e cycles:pp - otherwise it's easy to see profiling
artifacts, especially in and around short functions like
clear_page_c().
Thanks,
Ingo
next prev parent reply other threads:[~2011-05-30 19:33 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-30 8:30 [PATCH v2 1/8] kvm tools: Use correct value for user signal base Sasha Levin
2011-05-30 8:30 ` [PATCH v2 2/8] kvm tools: Remove wrong global definition of kvm Sasha Levin
2011-05-30 8:38 ` Ingo Molnar
2011-05-30 8:59 ` Sasha Levin
2011-05-30 8:30 ` [PATCH v2 3/8] kvm tools: Allow pausing guests Sasha Levin
2011-05-30 8:39 ` Ingo Molnar
2011-05-30 8:30 ` [PATCH v2 4/8] kvm tools: Pause/resume guest using SIGUSR2 Sasha Levin
2011-05-30 8:41 ` Ingo Molnar
2011-05-30 8:30 ` [PATCH v2 5/8] kvm tools: Add a brlock Sasha Levin
2011-05-30 8:30 ` [PATCH v2 6/8] kvm tools: Add rwlock wrapper Sasha Levin
2011-05-30 8:43 ` Ingo Molnar
2011-05-30 9:29 ` Pekka Enberg
2011-05-30 9:34 ` Sasha Levin
2011-05-30 9:40 ` Pekka Enberg
2011-05-30 9:46 ` Sasha Levin
2011-05-30 9:48 ` Pekka Enberg
2011-05-30 9:54 ` Ingo Molnar
2011-05-30 11:11 ` Takuya Yoshikawa
2011-05-30 11:12 ` Sasha Levin
2011-05-30 11:26 ` Takuya Yoshikawa
2011-05-30 11:39 ` Avi Kivity
2011-05-30 11:49 ` Ingo Molnar
2011-05-30 11:55 ` Pekka Enberg
2011-05-30 11:58 ` Sasha Levin
2011-05-30 12:20 ` Ingo Molnar
2011-05-30 12:22 ` Sasha Levin
2011-05-30 12:25 ` Avi Kivity
2011-05-30 12:23 ` Avi Kivity
2011-05-30 12:30 ` Pekka Enberg
2011-05-30 12:32 ` Avi Kivity
2011-05-30 14:10 ` Ingo Molnar
2011-05-30 14:30 ` Avi Kivity
2011-05-30 14:43 ` Ingo Molnar
2011-05-30 14:50 ` Avi Kivity
2011-05-30 19:32 ` Ingo Molnar [this message]
2011-05-30 12:04 ` Avi Kivity
2011-05-30 12:36 ` Ingo Molnar
2011-05-30 12:44 ` Avi Kivity
2011-05-30 12:46 ` Pekka Enberg
2011-05-30 12:48 ` Avi Kivity
2011-05-30 13:05 ` Sasha Levin
2011-06-03 7:27 ` Sasha Levin
2011-06-03 7:34 ` Ingo Molnar
2011-06-03 7:54 ` Sasha Levin
2011-06-03 19:31 ` Paul E. McKenney
2011-06-03 19:56 ` Sasha Levin
2011-06-03 20:22 ` Paul E. McKenney
2011-06-03 21:03 ` Sasha Levin
2011-06-03 21:20 ` Paul E. McKenney
2011-06-03 22:54 ` Sasha Levin
2011-06-03 23:05 ` Paul E. McKenney
2011-06-04 6:26 ` Sasha Levin
2011-06-04 16:30 ` Paul E. McKenney
2011-06-14 22:26 ` Sasha Levin
2011-06-14 23:42 ` Paul E. McKenney
2011-06-15 1:25 ` Sasha Levin
2011-06-15 4:22 ` Paul E. McKenney
2011-06-05 12:12 ` Avi Kivity
2011-05-30 14:16 ` Takuya Yoshikawa
2011-05-30 9:56 ` Ingo Molnar
2011-05-30 10:05 ` Sasha Levin
2011-05-30 10:13 ` Ingo Molnar
2011-05-30 10:22 ` Sasha Levin
2011-05-30 10:30 ` Ingo Molnar
2011-05-30 10:41 ` Sasha Levin
2011-05-30 8:30 ` [PATCH v2 7/8] kvm tools: Add debug mode to brlock Sasha Levin
2011-05-30 8:30 ` [PATCH v2 8/8] kvm tools: Use brlock in MMIO and IOPORT Sasha Levin
2011-05-30 8:47 ` Ingo Molnar
2011-05-30 8:56 ` Sasha Levin
2011-05-30 8:35 ` [PATCH v2 1/8] kvm tools: Use correct value for user signal base Ingo Molnar
2011-05-30 8:40 ` Sasha Levin
2011-05-30 8:49 ` Ingo Molnar
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