Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 28 Oct 2003 14:37:52 +1300 | From | Nigel Cunningham <> | Subject | Re: 2.6.0-test8/test9 io scheduler needs tuning? |
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I'll try it with my software suspend patch. Under 2.4, I get around 45 pages per jiffy written when suspending. Under 2.6, I'm currently getting 2-4, so any improvement should be obvious!
Regards,
Nigel
On Tue, 2003-10-28 at 12:50, Nick Piggin wrote: > cliff white wrote: > > >On Tue, 28 Oct 2003 05:52:45 +0800 > >Michael Frank <mhf@linuxmail.org> 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. > > > ______________________________________________________________________ > > 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; > } > > > _ -- Nigel Cunningham 495 St Georges Road South, Hastings 4201, New Zealand
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