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Subject: Re: [PATCH 6/8] readahead: add debug tracing event
From: Steven Rostedt <rostedt@goodmis.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        linux-fsdevel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
        Jens Axboe <jens.axboe@oracle.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Rik van Riel <riel@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        Andi Kleen <andi@firstfloor.org>
In-Reply-To: <20111121093846.764030336@intel.com>
References: <20111121091819.394895091@intel.com>
	 <20111121093846.764030336@intel.com>
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Date: Mon, 21 Nov 2011 09:01:15 -0500
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On Mon, 2011-11-21 at 17:18 +0800, Wu Fengguang wrote:
> plain text document attachment (readahead-tracer.patch)
> This is very useful for verifying whether the algorithms are working
> to our expectaions.
> 
> Example output:
> 
> # echo 1 > /debug/tracing/events/vfs/readahead/enable
> # cp test-file /dev/null
> # cat /debug/tracing/trace  # trimmed output
> readahead-initial(dev=0:15, ino=100177, req=0+2, ra=0+4-2, async=0) = 4
> readahead-subsequent(dev=0:15, ino=100177, req=2+2, ra=4+8-8, async=1) = 8
> readahead-subsequent(dev=0:15, ino=100177, req=4+2, ra=12+16-16, async=1) = 16
> readahead-subsequent(dev=0:15, ino=100177, req=12+2, ra=28+32-32, async=1) = 32
> readahead-subsequent(dev=0:15, ino=100177, req=28+2, ra=60+60-60, async=1) = 24
> readahead-subsequent(dev=0:15, ino=100177, req=60+2, ra=120+60-60, async=1) = 0
> 
> CC: Ingo Molnar <mingo@elte.hu>
> CC: Jens Axboe <jens.axboe@oracle.com>
> CC: Steven Rostedt <rostedt@goodmis.org>

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

> CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Acked-by: Rik van Riel <riel@redhat.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>