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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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WARNING: multiple messages have this Message-ID (diff)
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

  reply	other threads:[~2011-11-21 11:24 UTC|newest]

Thread overview: 116+ 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 ` Wu Fengguang
2011-11-21  9:18 ` Wu Fengguang
2011-11-21  9:18 ` [PATCH 1/8] block: limit default readahead size for small devices Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 10:00   ` Christoph Hellwig
2011-11-21 10:00     ` Christoph Hellwig
2011-11-21 11:24     ` Wu Fengguang [this message]
2011-11-21 11:24       ` Wu Fengguang
2011-11-21 12:47     ` Andi Kleen
2011-11-21 12:47       ` Andi Kleen
2011-11-21 14:46   ` Jeff Moyer
2011-11-21 14:46     ` Jeff Moyer
2011-11-21 14:46     ` Jeff Moyer
2011-11-21 22:52   ` Andrew Morton
2011-11-21 22:52     ` Andrew Morton
2011-11-21 22:52     ` Andrew Morton
2011-11-22 14:23     ` Jeff Moyer
2011-11-22 14:23       ` Jeff Moyer
2011-11-22 14:23       ` Jeff Moyer
2011-11-23 12:18     ` Wu Fengguang
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  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 10:01   ` Christoph Hellwig
2011-11-21 10:01     ` Christoph Hellwig
2011-11-21 11:35     ` Wu Fengguang
2011-11-21 11:35       ` Wu Fengguang
2011-11-24 22:28       ` Jan Kara
2011-11-24 22:28         ` Jan Kara
2011-11-25  0:36         ` Dave Chinner
2011-11-25  0:36           ` Dave Chinner
2011-11-28  2:39           ` Wu Fengguang
2011-11-28  2:39             ` Wu Fengguang
2011-11-30 13:04             ` Christian Ehrhardt
2011-11-30 13:04               ` Christian Ehrhardt
2011-11-30 13:04               ` Christian Ehrhardt
2011-11-30 13:29               ` Wu Fengguang
2011-11-30 13:29                 ` Wu Fengguang
2011-11-30 13:29                 ` Wu Fengguang
2011-11-30 16:09                 ` Jan Kara
2011-11-30 16:09                   ` Jan Kara
2011-11-21 13:16   ` Namhyung Kim
2011-11-21 13:16     ` Namhyung Kim
2011-11-21 13:24     ` Wu Fengguang
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  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 11:04   ` Steven Whitehouse
2011-11-21 11:04     ` Steven Whitehouse
2011-11-21 11:42     ` Wu Fengguang
2011-11-21 11:42       ` Wu Fengguang
2011-11-21 23:01   ` Andrew Morton
2011-11-21 23:01     ` Andrew Morton
2011-11-21 23:01     ` Andrew Morton
2011-11-23 12:47     ` Wu Fengguang
2011-11-23 12:47       ` Wu Fengguang
2011-11-23 20:31       ` Andrew Morton
2011-11-23 20:31         ` Andrew Morton
2011-11-29  3:42         ` Wu Fengguang
2011-11-29  3:42           ` Wu Fengguang
2011-11-21  9:18 ` [PATCH 4/8] readahead: record readahead patterns Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 23:19   ` Andrew Morton
2011-11-21 23:19     ` Andrew Morton
2011-11-21 23:19     ` Andrew Morton
2011-11-29  2:40     ` Wu Fengguang
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  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 14:17   ` Andi Kleen
2011-11-21 14:17     ` Andi Kleen
2011-11-22 14:14     ` Wu Fengguang
2011-11-22 14:14       ` Wu Fengguang
2011-11-21 23:29   ` Andrew Morton
2011-11-21 23:29     ` Andrew Morton
2011-11-21 23:32     ` Andi Kleen
2011-11-21 23:32       ` Andi Kleen
2011-11-29  3:23     ` Wu Fengguang
2011-11-29  3:23       ` Wu Fengguang
2011-11-29  4:49       ` Andrew Morton
2011-11-29  4:49         ` Andrew Morton
2011-11-29  6:41         ` Wu Fengguang
2011-11-29  6:41           ` Wu Fengguang
2011-11-29 12:29           ` 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  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 14:01   ` Steven Rostedt
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  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 23:33   ` Andrew Morton
2011-11-21 23:33     ` Andrew Morton
2011-11-21 23:33     ` Andrew Morton
2011-11-29  3:08     ` Wu Fengguang
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  9:18   ` Wu Fengguang
2011-11-21  9:18   ` Wu Fengguang
2011-11-21 23:36   ` Andrew Morton
2011-11-21 23:36     ` Andrew Morton
2011-11-21 23:36     ` Andrew Morton
2011-11-22 14:18     ` Wu Fengguang
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  9:56   ` Christoph Hellwig
2011-11-21 12:00   ` Wu Fengguang
2011-11-21 12:00     ` Wu Fengguang

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