From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: Bad write performance with libata-tj-stable-2.6.17.4-20060710, pcmcia based sata_sil24, PMP, and NCQ drive Date: Tue, 29 Aug 2006 22:27:26 +0900 Message-ID: <44F440BE.80000@gmail.com> References: <20060828230132.GB20189@geeks.org> <44F3A8FD.6090108@gmail.com> <20060829045816.GA21746@geeks.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from nz-out-0102.google.com ([64.233.162.207]:27335 "EHLO nz-out-0102.google.com") by vger.kernel.org with ESMTP id S964957AbWH2N2T (ORCPT ); Tue, 29 Aug 2006 09:28:19 -0400 Received: by nz-out-0102.google.com with SMTP id n1so1283377nzf for ; Tue, 29 Aug 2006 06:28:19 -0700 (PDT) In-Reply-To: <20060829045816.GA21746@geeks.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Derek Taubert Cc: linux-ide@vger.kernel.org Derek Taubert wrote: >> >From iostat -k 10: >>> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn >>> sda 2428.64 2422.46 667.66 24273 6690 >>> sda 36.84 23.72 1667.87 237 16662 >>> sda 2440.60 2434.90 616.00 24349 6160 >>> The read rate is curious (should be 0)... >>> >>> Top shows 1% user, 3% system, 93% wait. >> It seems some kind of read IO is in progress. Can you repeat the test >> on an unused/idle (iostat -k 10 shows all zeros...) drive? The above >> result actually looks good if you consider both read and write sides. > > I think that 3MBytes/sec total for a drive that can read at 50MBytes/sec > on the same system is quite bad, especially since we're talking about > a linear write test. True, I was referring to both reads and writes. If both are in progress and they're apart on disk, the result looks normal. >> The result doesn't seem to indicate any problem in libata or any storage >> related kernel subsystem. I would track down the reader first. > > This drive has only been partitioned; there is no filesystem on it. So, > it certainly isn't mounted anywhere. There honestly isn't _anything_ > other than the dd going on to sda1, and that's the only partition on > sda. Hmmm... >>> 2) hdparm -C for all 4 drives always shows "drive state is: standby" >>> even when I'm certain that the drives are active. >> hdparm -C says the same thing for my drive. I think it's safe to >> ignore. Hmmm... it needs to be tracked down. Maybe some problem in >> HDIO ioctl implementation in libata. > > It's a "nice to have" for using smartd. ie: don't spin the drives up to > poll the failure attributes, but they should be checked if the drive's > already active. I don't really understand what you mean. Can you elaborate? >>> I'd really like some assistance debugging the write performance issue. >>> The "hdparm -C" issue would be gravy... >> Please track down the reader. > > Before running dd (fuser -v /dev/sda1 shows nothing): [--snip--] Can you try 'dd if=/dev/zero of=/dev/sdX bs=4M count=1'? -- tejun