From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ofer Heifetz Subject: RE: Splice status Date: Tue, 13 Jul 2010 17:40:14 +0300 Message-ID: References: <1278334254.2877.158.camel@edumazet-laptop> <1278388580.2466.305.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Cc: Eric Dumazet , Jens Axboe , "netdev@vger.kernel.org" To: Changli Gao Return-path: Received: from galiil.marvell.com ([199.203.130.254]:31858 "EHLO galiil.marvell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754929Ab0GMOlh convert rfc822-to-8bit (ORCPT ); Tue, 13 Jul 2010 10:41:37 -0400 In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: I profiled the splice iometer write run and noticed that blk_end_request_err is being called many times, it looks like a good candidate for the high iowait, need to debug the root cause for it. -Ofer -----Original Message----- From: Changli Gao [mailto:xiaosuo@gmail.com] Sent: Tuesday, July 13, 2010 4:58 PM To: Ofer Heifetz Cc: Eric Dumazet; Jens Axboe; netdev@vger.kernel.org Subject: Re: Splice status On Tue, Jul 13, 2010 at 8:42 PM, Ofer Heifetz wrote: > Write and re-write numbers are in MBps. > Iozone performs re-write meaning reads a chunk of data and writes it back, so basically the performance for this operation should be quiet high since kernel caches usage. > > I forgot to mention that I used EXT4 fs. Maybe it is caused by this line in generic_file_splice_write(): balance_dirty_pages_ratelimited_nr(mapping, nr_pages); Please try to test it again without this line. -- Regards, Changli Gao(xiaosuo@gmail.com)