From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755674AbZDCCF6 (ORCPT ); Thu, 2 Apr 2009 22:05:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756453AbZDCCFo (ORCPT ); Thu, 2 Apr 2009 22:05:44 -0400 Received: from rv-out-0506.google.com ([209.85.198.224]:30939 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757523AbZDCCFm convert rfc822-to-8bit (ORCPT ); Thu, 2 Apr 2009 22:05:42 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=RcnDRANzaAgXLcGsC/vL8F7FZgfCBN8E+jNBVdmvUbEgdJYK5L2fd2TLtuIGEzWzRK sq7hhQGY0RdD/W03hNRQmfrPJEsv/96Zv7ceDzEpS+z88eMakkU9fJIEquRj/76Fpoqb /DwmbIwvd2JjJeMNqJpQjXLEUbC/9YJ2p+Aj0= MIME-Version: 1.0 In-Reply-To: <72dbd3150904021855v440f46a7oc21a7ed28fbfcb13@mail.gmail.com> References: <49CCCB0A.6070701@nokia.com> <9b1675090904021724t2fb0a671uc10d8e7bcba0bc5c@mail.gmail.com> <9b1675090904021728y35776377u327f2266d06e2f29@mail.gmail.com> <72dbd3150904021855v440f46a7oc21a7ed28fbfcb13@mail.gmail.com> Date: Thu, 2 Apr 2009 20:05:40 -0600 Message-ID: <9b1675090904021905o7e0cec64lfe4a5372777908b6@mail.gmail.com> Subject: Re: EXT4-ish "fixes" in UBIFS From: "Trenton D. Adams" To: David Rees Cc: Christian Kujau , Artem Bityutskiy , Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 2, 2009 at 7:55 PM, David Rees wrote: > On Thu, Apr 2, 2009 at 5:28 PM, Trenton D. Adams > wrote: >> On Thu, Apr 2, 2009 at 6:24 PM, Trenton D. Adams >> wrote: >>> Yes, mounting "-o sync" does improve ext3 performance.  It sucks >>> though, because I do want quick writes.  And mounting with sync option >>> slows down to disk io speeds.  In my case, that's between 20 and 23 >>> megabytes per second *big frown, quivering lip, and tears in my eyes*. >>> :P >>> >> >> Oh, I should have clarified.  It improves performance under heavy >> load.  Under normal load, mounting without sync is fine.  What I tend >> to do is mount with "remount,rw,sync" when heavy load is starting. >> Then my system goes slowly, but latency is good.  Then, when it's all >> done (say a big compile, or job, or whatever), I remount without sync >> again. >> >> I'm thinking of writing a script that monitors performance, and >> remounts as needed, lol.  WHAT A HACK. hehe. > > All you're doing here is implementing the lowering of dirty data > limits in the VM dynamically based on how long fsyncs take. > > Linus outlined this specific strategy as "the ideal siutation" > somewhere in the depths of "That filesystem thread". I thought he said it was a HORRIBLE solution. :D I recall him slamming Andrew over it. Unless you're referring to the kernel actually doing it on the fly. > > Look at the new in 2.6.29 dirty*bytes parameters in > Documentation/sysctl/vm.txt for more info.  By lowering those values, > you can effectively turn normal writes into synchronous writes which > will greatly reduce latency of fsync under heavy write load. > > In previous kernels you can tweak dirty_ratio and > dirty_background_ratio, but they don't have the granularity of the new > knobs.  Although if you are talking about just remounting in sync > mode, they may work for you at least as a proof of concept. ;-) > > -Dave > dirty_ratio and dirty_background never really had any affect for me. I'll look into the other parameters. Waiting for the checkout again, as I am currently under a heavy rsync load (*rolls eyes*). Thanks.