From: Mike Fedyk Subject: Re: [Regression] Filesystem I/O is CPU-bound in rc7 and rc8 Date: Fri, 19 Feb 2010 13:22:45 -0800 Message-ID: <93cdabd21002191322g7ea13d8bk52f1545df913f07@mail.gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, jfs-discussion@lists.sourceforge.net To: James Cloos Return-path: In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sat, Feb 13, 2010 at 7:11 PM, James Cloos wrote: > Sometime between rc6 and rc7 all filesystem I/O started using 100% CP= U, > usually on the order of 60% sys, 40% user. > > I've tried this with each of ext4, jfs and btrfs filesystems. =C2=A0A= ll show > the same issue. > Are you sure you're not running with any of the debugging options enabled? I see the same, but I have debugging enabled (rawhide kernel). > Using dd(1) to read from the block specials directly works as well an= d > as fast as it always has; only reading or writing to mounted filesyst= ems > is affected. > > Box is 32-bit x86, PentiumIII-M; drives are ide using libata. > > If the btrfs fs is mounted, the slowdown is enought to trigger the > hung_task call trace (120s) on the btrfs-transac process. > > But the regression is just as apparent when only jfs and ext4 are mou= nted. > > The only filesystems I've found which avoid the regression are tmpfs = and > devtmpfs. > > I didn't have time to write up a report when I noticed this in rc7 bu= t > had to boot back into rc6 for work. > > Some of the commits since rc7 looked like they might have addressed t= his > regression, but it persists in rc8. > > -JimC > -- > James Cloos =C2=A0 =C2=A0 =C2=A0 =C2=A0 OpenPGP: = 1024D/ED7DAEA6 > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs= " in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.ht= ml > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html