From mboxrd@z Thu Jan 1 00:00:00 1970 From: Changli Gao Subject: Re: Splice status Date: Tue, 13 Jul 2010 20:32:17 +0800 Message-ID: References: <1278334254.2877.158.camel@edumazet-laptop> <1278388580.2466.305.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , Jens Axboe , "netdev@vger.kernel.org" To: Ofer Heifetz Return-path: Received: from mail-vw0-f46.google.com ([209.85.212.46]:38045 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754787Ab0GMMci convert rfc822-to-8bit (ORCPT ); Tue, 13 Jul 2010 08:32:38 -0400 Received: by vws5 with SMTP id 5so5741210vws.19 for ; Tue, 13 Jul 2010 05:32:37 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Jul 13, 2010 at 7:41 PM, Ofer Heifetz wrote= : > Hi, > > I wanted to let you know that I have been testing Samba splice on Mar= vell 6282 SoC on 2.6.35_rc3 and noticed that it gave worst performance = than not using it and also noticed that on re-writing file the iowait i= s high. > > iometer using 2G file (file is created before test) > > Splice =A0write cpu% iow% > ----------------------- > =A0No =A0 =A0 58 =A0 =A098 =A0 =A00 > Yes =A0 =A0 14 =A0 100 =A0 48 > > iozone using 2G file (file created during test) > > Splice =A0write cpu% iow% =A0re-write cpu% iow% > ------------------------------------------- > =A0No =A0 =A0 35 =A0 =A085 =A0 =A04 =A0 =A058.2 =A0 =A0 70 =A0 =A00 > Yes =A0 =A0 33 =A0 =A085 =A0 =A04 =A0 =A015.7 =A0 =A0100 =A0 58 > > Any clue why splice introduces a high iowait? > I noticed samba uses up to 16K per splice syscall, changing the samba= to try more did not help, so I guess it is a kernel limitation. > > -Ofer > What does the column write means? And what do you mean by saying re-write? Thanks. --=20 Regards, Changli Gao(xiaosuo@gmail.com)