From: "Darrick J. Wong" Subject: Re: [PATCH 3/3] block: reimplement FLUSH/FUA to support merge Date: Wed, 23 Mar 2011 16:37:01 -0700 Message-ID: <20110323233701.GA24354@tux1.beaverton.ibm.com> References: <1295625598-15203-1-git-send-email-tj@kernel.org> <1295625598-15203-4-git-send-email-tj@kernel.org> <20110121185617.GI12072@redhat.com> <20110123102526.GA23121@htj.dyndns.org> <20110124203155.GA32261@tux1.beaverton.ibm.com> <20110125102128.GO27510@htj.dyndns.org> <4D3EB66C.4090006@kernel.dk> Reply-To: djwong@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Tejun Heo , Vivek Goyal , tytso@mit.edu, shli@kernel.org, neilb@suse.de, adilger.kernel@dilger.ca, jack@suse.cz, snitzer@redhat.com, linux-kernel@vger.kernel.org, kmannth@us.ibm.com, cmm@us.ibm.com, linux-ext4@vger.kernel.org, rwheeler@redhat.com, hch@lst.de, josef@redhat.com To: Jens Axboe Return-path: Received: from e3.ny.us.ibm.com ([32.97.182.143]:58769 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933061Ab1CWXhF (ORCPT ); Wed, 23 Mar 2011 19:37:05 -0400 Content-Disposition: inline In-Reply-To: <4D3EB66C.4090006@kernel.dk> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jan 25, 2011 at 12:39:24PM +0100, Jens Axboe wrote: > On 2011-01-25 11:21, Tejun Heo wrote: > > Hello, Darrick. > > > > On Mon, Jan 24, 2011 at 12:31:55PM -0800, Darrick J. Wong wrote: > >>> So, I think it's better to start with something simple and improve it > >>> with actual testing. If the current simple implementation can match > >>> Darrick's previous numbers, let's first settle the mechanisms. We can > >> > >> Yep, the fsync-happy numbers more or less match... at least for 2.6.37: > >> http://tinyurl.com/4q2xeao > > > > Good to hear. Thanks for the detailed testing. > > > >> I'll give 2.6.38-rc2 a try later, though -rc1 didn't boot for me, so these > >> numbers are based on a backport to .37. :( > > > > Well, there hasn' been any change in the area during the merge window > > anyway, so I think testing on 2.6.37 should be fine. > > > >>> I don't really think we should design the whole thing around broken > >>> devices which incorrectly report writeback cache when it need not. > >>> The correct place to work around that is during device identification > >>> not in the flush logic. > >> > >> elm3a4_sas and elm3c71_extsas advertise writeback cache yet the > >> flush completion times are suspiciously low. I suppose it could be > >> useful to disable flushes to squeeze out that last bit of > >> performance, though I don't know how one goes about querying the > >> disk array to learn if there's a battery behind the cache. I guess > >> the current mechanism (admin knob that picks a safe default) is good > >> enough. > > > > Yeap, that or a blacklist of devices which lie. > > > > Jens, what do you think? If you don't object, let's put this through > > linux-next. > > I like the approach, I'll queue it up for 2.6.39. Is this patch set still on the merge list for 2.6.39? --D > > -- > Jens Axboe >