From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263782AbTJ0XvY (ORCPT ); Mon, 27 Oct 2003 18:51:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263783AbTJ0XvY (ORCPT ); Mon, 27 Oct 2003 18:51:24 -0500 Received: from mail-06.iinet.net.au ([203.59.3.38]:58523 "HELO mail.iinet.net.au") by vger.kernel.org with SMTP id S263782AbTJ0XvS (ORCPT ); Mon, 27 Oct 2003 18:51:18 -0500 Message-ID: <3F9DAF2C.8010308@cyberone.com.au> Date: Tue, 28 Oct 2003 10:50:04 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030827 Debian/1.4-3 X-Accept-Language: en MIME-Version: 1.0 To: cliff white CC: Michael Frank , linux-kernel@vger.kernel.org Subject: Re: 2.6.0-test8/test9 io scheduler needs tuning? References: <200310261201.14719.mhf@linuxmail.org> <20031027145531.2eb01017.cliffw@osdl.org> In-Reply-To: <20031027145531.2eb01017.cliffw@osdl.org> Content-Type: multipart/mixed; boundary="------------080105000501010502090303" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------080105000501010502090303 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cliff white wrote: >On Tue, 28 Oct 2003 05:52:45 +0800 >Michael Frank wrote: > > >>To my surprise 2.6 - which used to do better then 2.4 - does no longer >>handle these test that well. >> >>Generally, IDE IO throughput is _very_ uneven and IO _stops_ at times with the >>system cpu load very high (and the disk LED off). >> >>IMHO the CPU scheduling is OK but the IO scheduling acts up here. >> >>The test system is a 2.4GHz P4 with 512M RAM and a 55MB/s udma IDE harddisk. >> >>The tests load the system to loadavg > 30. IO should be about 20MB/s on avg. >> >>Enclosed are vmstat -1 logs for 2.6-test9-Vanilla, followed by 2.6-test8-Vanilla >>(-mm1 behaves similar), 2.4.22-Vanilla and 2.4.21+swsusp all compiled wo preempt. >> >>IO on 2.6 stops now for seconds at a time. -test8 is worse than -test9 >> > >We see the same delta at OSDL. Try repeating your tests with 'elevator=deadline' >to confirm. >For example, on the 8-cpu platform: >STP id Kernel Name MaxJPM Change Options >281669 linux-2.6.0-test8 7014.42 0.0 >281671 linux-2.6.0-test8 8294.94 +18.26% elevator=deadline > >The -mm kernels don't show this big delta. We also do not see this delta on >smaller machines > I'm working with Randy to fix this. Attached is what I have so far. See how you go with it. --------------080105000501010502090303 Content-Type: text/plain; name="as-fix.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="as-fix.patch" linux-2.6-npiggin/drivers/block/as-iosched.c | 30 ++++++--------------------- 1 files changed, 7 insertions(+), 23 deletions(-) diff -puN drivers/block/as-iosched.c~as-fix drivers/block/as-iosched.c --- linux-2.6/drivers/block/as-iosched.c~as-fix 2003-10-27 14:53:47.000000000 +1100 +++ linux-2.6-npiggin/drivers/block/as-iosched.c 2003-10-27 14:54:04.000000000 +1100 @@ -99,7 +99,6 @@ struct as_data { sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */ struct list_head *dispatch; /* driver dispatch queue */ struct list_head *hash; /* request hash */ - unsigned long new_success; /* anticipation success on new proc */ unsigned long current_batch_expires; unsigned long last_check_fifo[2]; int changed_batch; /* 1: waiting for old batch to end */ @@ -585,18 +584,11 @@ static void as_antic_stop(struct as_data int status = ad->antic_status; if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) { - struct as_io_context *aic; - if (status == ANTIC_WAIT_NEXT) del_timer(&ad->antic_timer); ad->antic_status = ANTIC_FINISHED; /* see as_work_handler */ kblockd_schedule_work(&ad->antic_work); - - aic = ad->io_context->aic; - if (aic->seek_samples == 0) - /* new process */ - ad->new_success = (ad->new_success * 3) / 4 + 256; } } @@ -612,14 +604,8 @@ static void as_antic_timeout(unsigned lo spin_lock_irqsave(q->queue_lock, flags); if (ad->antic_status == ANTIC_WAIT_REQ || ad->antic_status == ANTIC_WAIT_NEXT) { - struct as_io_context *aic; ad->antic_status = ANTIC_FINISHED; kblockd_schedule_work(&ad->antic_work); - - aic = ad->io_context->aic; - if (aic->seek_samples == 0) - /* new process */ - ad->new_success = (ad->new_success * 3) / 4; } spin_unlock_irqrestore(q->queue_lock, flags); } @@ -708,11 +694,10 @@ static int as_can_break_anticipation(str return 1; } - if (ad->new_success < 256 && - (aic->seek_samples == 0 || aic->ttime_samples == 0)) { + if (aic->seek_samples == 0 || aic->ttime_samples == 0) { /* - * Process has just started IO and we have a bad history of - * success anticipating on new processes! + * Process has just started IO. Don't anticipate. + * TODO! Must fix this up. */ return 1; } @@ -1292,7 +1277,7 @@ fifo_expired: ad->changed_batch = 0; - arq->request->flags |= REQ_SOFTBARRIER; +// arq->request->flags |= REQ_SOFTBARRIER; } /* @@ -1391,6 +1376,7 @@ static void as_add_request(struct as_dat } else { as_add_aliased_request(ad, arq, alias); + /* * have we been anticipating this request? * or does it come from the same process as the one we are @@ -1427,8 +1413,6 @@ static void as_requeue_request(request_q /* Stop anticipating - let this request get through */ as_antic_stop(ad); - - return; } static void @@ -1437,10 +1421,12 @@ as_insert_request(request_queue_t *q, st struct as_data *ad = q->elevator.elevator_data; struct as_rq *arq = RQ_DATA(rq); +#if 0 /* barriers must flush the reorder queue */ if (unlikely(rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER) && where == ELEVATOR_INSERT_SORT)) where = ELEVATOR_INSERT_BACK; +#endif switch (where) { case ELEVATOR_INSERT_BACK: @@ -1823,8 +1809,6 @@ static int as_init(request_queue_t *q, e if (ad->write_batch_count < 2) ad->write_batch_count = 2; - ad->new_success = 512; - return 0; } _ --------------080105000501010502090303--