From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFT] major libata update Date: Wed, 17 May 2006 13:44:35 +0900 Message-ID: <446AAA33.5010800@gmail.com> References: <20060515170006.GA29555@havoc.gtf.org> <4469B93E.6010201@emc.com> <4469E0DB.1040709@garzik.org> <4469EEC0.4060907@gmail.com> <446A1A21.80501@emc.com> <446A63F6.5030706@gmail.com> <446A6615.6050701@garzik.org> <446A678E.8030403@garzik.org> <446A6ECD.7080104@garzik.org> <446A734A.6020504@gmail.com> <446A7504.9000201@gmail.com> <446A88DF.5060705@emc.com> <446A7E4A.1080003@gmail.com> <446A9F13.4020907@emc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from py-out-1112.google.com ([64.233.166.178]:38256 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S1751243AbWEQEom (ORCPT ); Wed, 17 May 2006 00:44:42 -0400 Received: by py-out-1112.google.com with SMTP id z59so161411pyg for ; Tue, 16 May 2006 21:44:41 -0700 (PDT) In-Reply-To: <446A9F13.4020907@emc.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Ric Wheeler Cc: Jeff Garzik , linux-ide@vger.kernel.org, Mark Lord , Jens Axboe Ric Wheeler wrote: > May 17 03:30:54 centera kernel: [start_ordered ]: BIO d08998c0 3357330 4096 > May 17 03:30:54 centera kernel: [start_ordered ]: ordered=1 in_flight=0 > May 17 03:30:54 centera kernel: [blk_do_ordered ]: start_ordered ed3553c0->dfe2bd28 > May 17 03:30:54 centera kernel: [elv_next_request ]: dfe2bd28 (bar) > May 17 03:30:54 centera kernel: [ordered_bio_endio ]: q->orderr=0 error=0 > May 17 03:30:54 centera kernel: [flush_dry_bio_endio ]: BIO f18ffa00 3357330 4096 > May 17 03:30:54 centera kernel: [blk_ordered_complete_seq]: ordseq=17 seq=08 orderr=0 error=0 > May 17 03:30:54 centera kernel: [blk_ordered_complete_seq]: sequence complete > May 17 03:30:54 centera kernel: [ordered_bio_endio ]: q->orderr=0 error=0 > May 17 03:30:54 centera kernel: [flush_dry_bio_endio ]: BIO f18ff300 3357330 4096 > May 17 03:30:54 centera kernel: [blk_ordered_complete_seq]: ordseq=17 seq=08 orderr=0 error=0 > May 17 03:30:54 centera kernel: [blk_ordered_complete_seq]: sequence complete [--snip--] Combined with your boot log, everything seems as expected. Write cache is disabled, so the chosen ordered mode is 0x1 - DRAIN only. In the log you've posted, there are no pending IOs on barrier issue, so the barrier is executed directly and then the sequence is complete. If there were other requests pending, all that happens would be waiting for them to finish before issuing the barrier. If you turned on write cache after the machine booted, what method did you use to turn on write cache? If you issued the command directly using sg to an active device (usage count >= 1), SCSI doesn't snoop such commands and thus it won't adjust ordered mode automatically. However, sd forces disk revalidation (and thus ordered reconfiguration) if you change cache mode via /sys/class/scsi_disk/X\:0\:0\:0/cache_type. -- tejun