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From: fche@redhat.com (Frank Ch. Eigler)
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
	Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Fengguang Wu <wfg@mail.ustc.edu.cn>,
	hirofumi@mail.parknet.co.jp, galak@kernel.crashing.org,
	zaitcev@redhat.com, greg@kroah.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, mbligh@google.com
Subject: Re: [PATCH] writeback: remove unnecessary wait in throttle_vm_writeout()
Date: Fri, 28 Sep 2007 15:50:14 -0400	[thread overview]
Message-ID: <y0mabr6vabt.fsf@ton.toronto.redhat.com> (raw)
In-Reply-To: <20070928175756.GA16066@Krystal> (Mathieu Desnoyers's message of "Fri, 28 Sep 2007 13:57:56 -0400")


Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> writes:

>> [...]
>> > I totally agree with Ingo here. Having a basic instrumentation that is
>> > enabled by default will help to identify code paths causing unexpected
>> > delays in the kernel. [...]
>
>> It is. See: CONFIG_VM_EVENT_COUNTERS and all the other vm specific
>> crap littered in /proc/ (buddyinfo, zoneinfo, meminfo, etc).  [...]

> Isn't the actual instrumentation present in the VM subsystem
> consisting mostly of event counters ? This kind of profiling
> provides limited help in following specific delays in the
> kernel. [...]

These existing VM events/counters could be a good target for a second
worked-out example (after blktrace) of reimplementation using generic
markers.

- FChE

  reply	other threads:[~2007-09-28 19:51 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20070927015016.GA11080@mail.ustc.edu.cn>
2007-09-27  1:50 ` Fengguang Wu
2007-09-27 15:16   ` Rik van Riel
     [not found]     ` <20070928011846.GA5496@mail.ustc.edu.cn>
2007-09-28  1:18       ` Fengguang Wu
2007-09-27 20:47   ` Andrew Morton
2007-09-28  8:02     ` Ingo Molnar
2007-09-27 22:59       ` Nick Piggin
2007-09-28 16:23       ` Mathieu Desnoyers
2007-09-28  0:10         ` Nick Piggin
2007-09-28 17:57           ` Mathieu Desnoyers
2007-09-28 19:50             ` Frank Ch. Eigler [this message]
2007-09-28 20:25             ` Nick Piggin
2007-09-27 21:49   ` Nick Piggin

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