From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: raid5-cache I/O path improvements V2 Date: Mon, 14 Sep 2015 19:11:22 +0000 Message-ID: References: <1442038638-6947-1-git-send-email-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <1442038638-6947-1-git-send-email-hch@lst.de> Content-Language: en-US Content-ID: <77E12A3A7CA9624BBD5B5DEB67BA1F4D@fb.com> Sender: linux-raid-owner@vger.kernel.org To: Christoph Hellwig , "neilb@suse.de" Cc: "linux-raid@vger.kernel.org" , Kernel Team , "dan.j.williams@intel.com" List-Id: linux-raid.ids On 9/11/15, 11:17 PM, "Christoph Hellwig" wrote: >Hi Shaohua, hi Neil, > >this series contains a few updates to the raid5-cache feature. > >The first patch just ports it to the post-4.2 block layer. As part of >that >I noticed that it currently doesn't handle I/O errors - fixes for that >will >follow. > >The second and third patch simplify the I/O unit state machine and reduce >latency and memory usage for the I/O units. The remainder are just a >couple >of cleanups in this area that I stumbled upon. > >Changes since V1: > - only use REQ_FUA if supported natively by the log device Hi Christoph, I finally got some data with a Samsung SSD, which supports fua. Controller is ahci. Test is a simple fio with all full stripe write. libata.fua=0, throughput 247m/s libata.fua=1, throughput 74m/s fua is significantly slower. I think we need a sysfs config to enable fua. Thanks, Shaohua