From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yufen Yu Subject: Re: [PATCH v5 00/16] md/raid5: set STRIPE_SIZE as a configurable value Date: Wed, 8 Jul 2020 21:14:49 +0800 Message-ID: <0dd1ebed-2802-2bef-48f0-87bbdd2ee8e5@huawei.com> References: <20200702120628.777303-1-yuyufen@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-raid-owner@vger.kernel.org To: Song Liu Cc: linux-raid , NeilBrown , Guoqing Jiang , Hou Tao List-Id: linux-raid.ids On 2020/7/3 7:00, Song Liu wrote: > On Thu, Jul 2, 2020 at 5:05 AM Yufen Yu wrote: >> >> Hi, all >> >> For now, STRIPE_SIZE is equal to the value of PAGE_SIZE. That means, RAID5 >> will issue each bio to disk at least 64KB when PAGE_SIZE is 64KB in arm64. >> However, filesystem usually issue bio in the unit of 4KB. Then, RAID5 may >> waste resource of disk bandwidth. >> >> To solve the problem, this patchset try to set stripe_size as a configuare >> value. The default value is 4096. We will add a new sysfs entry and set it >> by writing a new value, likely: >> >> echo 16384 > /sys/block/md1/md/stripe_size > > Higher level question: do we need to support page size that is NOT 4kB > times power > of 2? Meaning, do we need to support 12kB, 20kB, 24kB, etc. If we only > supports, 4kB, > 8kB, 16kB, 32kB, etc. some of the logic can be simpler. Yeah, I think we just support 4kb, 8kb, 16kb, 32kb... is enough. But Sorry that I don't know what logic can be simpler in current implementation. I mean it also need to allocate page, and record page offset. Thanks, Yufen