From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: write performance difference 3.18.21/git f2fs Date: Fri, 2 Oct 2015 09:46:45 -0700 Message-ID: <20151002164645.GA2446@jaegeuk-mac02.mot.com> References: <01bf01d0f777$45df5ee0$d19e1ca0$@samsung.com> <20150926032218.GA4311@schmorp.de> <20150926052551.GA2243@schmorp.de> <20150926075253.GD13619@jaegeuk-mac02.hsd1.ca.comcast.net> <20150926135957.GB9860@schmorp.de> <20150928175944.GA16945@jaegeuk-mac02.mot.com> <20150929110204.GA7608@schmorp.de> <20150929231310.GA6010@jaegeuk-mac02.mot.com> <20151001121120.GA7340@schmorp.de> <20151001185124.GA9803@schmorp.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Zi3Ue-0004iC-Ll for linux-f2fs-devel@lists.sourceforge.net; Fri, 02 Oct 2015 16:47:36 +0000 Received: from mail.kernel.org ([198.145.29.136]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Zi3Ud-0000d2-Af for linux-f2fs-devel@lists.sourceforge.net; Fri, 02 Oct 2015 16:47:36 +0000 Content-Disposition: inline In-Reply-To: <20151001185124.GA9803@schmorp.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Marc Lehmann Cc: linux-f2fs-devel@lists.sourceforge.net On Thu, Oct 01, 2015 at 08:51:24PM +0200, Marc Lehmann wrote: > On Thu, Oct 01, 2015 at 02:11:20PM +0200, Marc Lehmann wrote: > > WOW, THAT HELPED A LOT. While the peak throughput seems quite a bit lower > > Ok, for completeness, here is the full log and a description of what was > going on. > > http://data.plan9.de/f2fs.s64.noinline.full.trace.xz Now, I can see much clean patterns. > status at the end + some idle time > http://ue.tst.eu/d16cf98c72fe9ecbac178ded47a21396.txt > > It was faster than the reader till roughtly the 1.2TB mark, after > which it acquired longish episodes of being <<50MB/s (for example, > around 481842.363964), and also periods of ~20kb/s, due to many small > WRITE_SYNC's in a row (e.g. at 482329.101222 and 490189.681438, > http://ue.tst.eu/cc94978eafc736422437a4ab35862c12.txt). The small > WRITE_SYNCs did not always result in this behaviour by the disk, though. Hmm, this is because of FS metadata flushes in background. I pushed one patch, can you get it through v3.18 branch? > After that, it was generally write-I/O bound. > > Also, the gc seemed to have kicked in at around that time, which is kind > of counterproductive. I increased the gc_* values in /sys, but don't know > if that had any effect. > > Most importantly, f2fs always recovered and had periods of much faster > writes (>= 120MB/s), so it's not the case that f2fs somehow saturates the > internal cache and then becomes slow forever. > > Overall, the throughput was 83MB/s, which is 20% worse than stock 3.18, but > still way beyond what any other filesystem could do. Cool. > Also, writing 1TB in a single session, with somewhat reduced speed > afterwards, would be enough for my purposes, i.e. I can live with that > (still, gigabit speeds would be nice of course, as that is the data rate I > often deal with). > > Notwithstanding any other improvements you might implement, f2fs has now > officially become my choice for SMR drives, the only remaining thing > needed is to convince me of its stability - it seems getting a kernel > with truly stable f2fs is a bit of a game of chance still, but I guess > confidence will come with more tests and actualy using it in production, > which I will do soon. > > -- > The choice of a Deliantra, the free code+content MORPG > -----==- _GNU_ http://www.deliantra.net > ----==-- _ generation > ---==---(_)__ __ ____ __ Marc Lehmann > --==---/ / _ \/ // /\ \/ / schmorp@schmorp.de > -=====/_/_//_/\_,_/ /_/\_\ > > ------------------------------------------------------------------------------ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ------------------------------------------------------------------------------