From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: [PATCH] readahead:add blk_run_backing_dev Date: Wed, 20 May 2009 10:52:58 +0800 Message-ID: <20090520025258.GA8318@localhost> References: <6.0.0.20.2.20090518183752.0581fdc0@172.19.0.2> <20090520100602.7438.A69D9226@jp.fujitsu.com> <6.0.0.20.2.20090520104202.071d0be8@172.19.0.2> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: KOSAKI Motohiro , Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , linux-mm , Jens Axboe To: Hisashi Hifumi Return-path: Content-Disposition: inline In-Reply-To: <6.0.0.20.2.20090520104202.071d0be8@172.19.0.2> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, May 20, 2009 at 09:43:18AM +0800, Hisashi Hifumi wrote: > > At 10:07 09/05/20, KOSAKI Motohiro wrote: > >(cc to Wu and linux-mm) > > > >> Hi. > >> > >> I wrote a patch that adds blk_run_backing_dev on page_cache_async_readahead > >> so readahead I/O is unpluged to improve throughput. > >> > >> Following is the test result with dd. > >> > >> #dd if=testdir/testfile of=/dev/null bs=16384 > >> > >> -2.6.30-rc6 > >> 1048576+0 records in > >> 1048576+0 records out > >> 17179869184 bytes (17 GB) copied, 224.182 seconds, 76.6 MB/s > >> > >> -2.6.30-rc6-patched > >> 1048576+0 records in > >> 1048576+0 records out > >> 17179869184 bytes (17 GB) copied, 206.465 seconds, 83.2 MB/s > >> > >> Sequential read performance on a big file was improved. > >> Please merge my patch. > > > >I guess the improvement depend on readahead window size. > >Have you mesure random access workload? > > I tried with iozone. But there was no difference. It does not impact random IO because the patch only modified the *async* readahead path, and random IO is obviously *sync* ones. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org