From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: Poor written performance with RAID5 on ARM64 Date: Tue, 19 Apr 2016 06:59:17 -0700 Message-ID: <20160419135917.GA2116@kernel.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: =?utf-8?B?5YiY5q2j5YWD?= Cc: linux-raid List-Id: linux-raid.ids On Mon, Apr 18, 2016 at 01:43:04PM +0800, =E5=88=98=E6=AD=A3=E5=85=83 w= rote: > Hi,everyone. I upgrade kernel form 3.14.x to 4.4.x recently on my AR= M64 > server. I create a RAID5 device with 8 disks on the server and have = a dd > test which like this "dd if=3D/dev/zero of=3D/dev/md5 bs=3D64K count=3D= 400000". > Before upgrade it can reach 700M/s written and only 500M/s after upgr= ade. > Then I disable the bitmap which means "mdadm create --bitmap=3Dnone",= the speed > can reach 800M/s with 4.4 kernel. I have a fast view on driver/md/bit= map.c > and got no answer. I doubt X86 platform has the same question. So, w= hat is > the most difference between 3.14.x and 4.4.x about md driver. Where c= ould I > found the ChangeLog or commit about the driver. Any answer would be t= hankful. did you observe any changes in iostat? Could you post blktrace from one= of the raid disk? Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html