From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: raid5-cache I/O path improvements V2 Date: Thu, 17 Sep 2015 03:53:26 +0200 Message-ID: <20150917015326.GA22865@lst.de> References: <1442038638-6947-1-git-send-email-hch@lst.de> <87a8so6t8f.fsf@notabene.neil.brown.name> <20150915215458.GA1943628@devbig084.prn1.facebook.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150915215458.GA1943628@devbig084.prn1.facebook.com> Sender: linux-raid-owner@vger.kernel.org To: Shaohua Li Cc: Neil Brown , Christoph Hellwig , "linux-raid@vger.kernel.org" , Kernel Team , "dan.j.williams@intel.com" List-Id: linux-raid.ids On Tue, Sep 15, 2015 at 02:54:59PM -0700, Shaohua Li wrote: > > I don't want a sysfs config if we can possibly avoid it. > > > > Christoph's code sets FUA on every block written to the log, both data > > and metadata. Is that really what we want? > > > > I don't know much of the hardware details, but wouldn't setting FUA and > > FLUSH on the last block written be just as effective and possibly faster > > (by giving more flexibility to lower layers)?? > > How is it different against without FUA, eg, doing a flush after several bios? It's just a more complicated version of doing the same..