From: Wu Fengguang <fengguang.wu@intel.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"Li, Shaohua" <shaohua.li@intel.com>,
Clemens Ladisch <clemens@ladisch.de>,
Jens Axboe <jens.axboe@oracle.com>,
Rik van Riel <riel@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH 1/8] block: limit default readahead size for small devices
Date: Mon, 21 Nov 2011 19:24:09 +0800 [thread overview]
Message-ID: <20111121112409.GA8895@localhost> (raw)
In-Reply-To: <20111121100004.GB5084@infradead.org>
On Mon, Nov 21, 2011 at 06:00:04PM +0800, Christoph Hellwig wrote:
> On Mon, Nov 21, 2011 at 05:18:20PM +0800, Wu Fengguang wrote:
> > This looks reasonable: smaller device tend to be slower (USB sticks as
> > well as micro/mobile/old hard disks).
> >
> > Given that the non-rotational attribute is not always reported, we can
> > take disk size as a max readahead size hint. This patch uses a formula
> > that generates the following concrete limits:
>
> Given that you mentioned the rotational flag and device size in this
> mail, as well as benchmarking with an intel SSD - did you measure
> how useful large read ahead sizes still are with highend Flash device
> that have extremly high read IOP rates?
I don't know -- I don't have access to such highend devices.
However the patch changelog has the simple test script. It would be
high appreciated if someone can help collect the data :)
Thanks,
Fengguang
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next prev parent reply other threads:[~2011-11-21 11:24 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-21 9:18 [PATCH 0/8] readahead stats/tracing, backwards prefetching and more Wu Fengguang
2011-11-21 9:18 ` [PATCH 1/8] block: limit default readahead size for small devices Wu Fengguang
2011-11-21 10:00 ` Christoph Hellwig
2011-11-21 11:24 ` Wu Fengguang [this message]
2011-11-21 12:47 ` Andi Kleen
2011-11-21 14:46 ` Jeff Moyer
2011-11-21 22:52 ` Andrew Morton
2011-11-22 14:23 ` Jeff Moyer
2011-11-23 12:18 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 2/8] readahead: make default readahead size a kernel parameter Wu Fengguang
2011-11-21 10:01 ` Christoph Hellwig
2011-11-21 11:35 ` Wu Fengguang
2011-11-24 22:28 ` Jan Kara
2011-11-25 0:36 ` Dave Chinner
2011-11-28 2:39 ` Wu Fengguang
2011-11-30 13:04 ` Christian Ehrhardt
2011-11-30 13:29 ` Wu Fengguang
2011-11-30 16:09 ` Jan Kara
2011-11-21 13:16 ` Namhyung Kim
2011-11-21 13:24 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 3/8] readahead: replace ra->mmap_miss with ra->ra_flags Wu Fengguang
2011-11-21 11:04 ` Steven Whitehouse
2011-11-21 11:42 ` Wu Fengguang
2011-11-21 23:01 ` Andrew Morton
2011-11-23 12:47 ` Wu Fengguang
2011-11-23 20:31 ` Andrew Morton
2011-11-29 3:42 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 4/8] readahead: record readahead patterns Wu Fengguang
2011-11-21 23:19 ` Andrew Morton
2011-11-29 2:40 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 5/8] readahead: add /debug/readahead/stats Wu Fengguang
2011-11-21 14:17 ` Andi Kleen
2011-11-22 14:14 ` Wu Fengguang
2011-11-21 23:29 ` Andrew Morton
2011-11-21 23:32 ` Andi Kleen
2011-11-29 3:23 ` Wu Fengguang
2011-11-29 4:49 ` Andrew Morton
2011-11-29 6:41 ` Wu Fengguang
2011-11-29 12:29 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 6/8] readahead: add debug tracing event Wu Fengguang
2011-11-21 14:01 ` Steven Rostedt
2011-11-21 9:18 ` [PATCH 7/8] readahead: basic support for backwards prefetching Wu Fengguang
2011-11-21 23:33 ` Andrew Morton
2011-11-29 3:08 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 8/8] readahead: dont do start-of-file readahead after lseek() Wu Fengguang
2011-11-21 23:36 ` Andrew Morton
2011-11-22 14:18 ` Wu Fengguang
2011-11-21 9:56 ` [PATCH 0/8] readahead stats/tracing, backwards prefetching and more Christoph Hellwig
2011-11-21 12:00 ` Wu Fengguang
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