Re: 2.4.20: Proccess stuck in __lock_page ...

Con Kolivas
2003-05-28T10:34:39Z

On Wed, 28 May 2003 20:25, Jens Axboe wrote:
> On Wed, May 28 2003, Andrew Morton wrote:
> > Matthias Mueller <matthias.mueller@rz.uni-karlsruhe.de> wrote:
> > > Works fine on my notebook. Good throughput and no mouse hangs anymore.
> >
> > Interesting.
> >
> > Could you please work out which change caused it? Go back to stock 2.4
> > and then apply this:
> >
> >
> > diff -puN drivers/block/ll_rw_blk.c~1 drivers/block/ll_rw_blk.c
> > --- 24/drivers/block/ll_rw_blk.c~1 2003-05-28 03:20:42.000000000 -0700
> > +++ 24-akpm/drivers/block/ll_rw_blk.c 2003-05-28 03:20:57.000000000 -0700
> > @@ -590,10 +590,10 @@ static struct request *__get_request_wai
> > register struct request *rq;
> > DECLARE_WAITQUEUE(wait, current);
> >
> > - generic_unplug_device(q);
> > add_wait_queue_exclusive(&q->wait_for_requests[rw], &wait);
> > do {
> > set_current_state(TASK_UNINTERRUPTIBLE);
> > + generic_unplug_device(q);
> > if (q->rq[rw].count == 0)
> > schedule();
> > spin_lock_irq(&io_request_lock);
>
> I think it was already established that this wasn't the reason. Was my
> first suspect too, though...
>
> > then this:
> >
> > diff -puN drivers/block/ll_rw_blk.c~2 drivers/block/ll_rw_blk.c
> > --- 24/drivers/block/ll_rw_blk.c~2 2003-05-28 03:21:03.000000000 -0700
> > +++ 24-akpm/drivers/block/ll_rw_blk.c 2003-05-28 03:21:09.000000000 -0700
> > @@ -590,7 +590,7 @@ static struct request *__get_request_wai
> > register struct request *rq;
> > DECLARE_WAITQUEUE(wait, current);
> >
> > - add_wait_queue_exclusive(&q->wait_for_requests[rw], &wait);
> > + add_wait_queue(&q->wait_for_requests[rw], &wait);
> > do {
> > set_current_state(TASK_UNINTERRUPTIBLE);
> > generic_unplug_device(q);
>
> Since we do a general wake_up(), only the order of wakeups matter here
> right (lifo vs fifo). Given that, the _exclusive() should be more fair
> possibly at the cost of a bit of throughput.
>
> > Then this (totally unlikely, don't bother):
> >
> > diff -puN drivers/block/ll_rw_blk.c~3 drivers/block/ll_rw_blk.c
> > --- 24/drivers/block/ll_rw_blk.c~3 2003-05-28 03:21:15.000000000 -0700
> > +++ 24-akpm/drivers/block/ll_rw_blk.c 2003-05-28 03:21:39.000000000 -0700
> > @@ -829,8 +829,7 @@ void blkdev_release_request(struct reque
> > */
> > if (q) {
> > list_add(&req->queue, &q->rq[rw].free);
> > - if (++q->rq[rw].count >= q->batch_requests &&
> > - waitqueue_active(&q->wait_for_requests[rw]))
> > + if (++q->rq[rw].count >= q->batch_requests)
> > wake_up(&q->wait_for_requests[rw]);
> > }
> > }
>
> Well it's the only one left :). But you are right, try one of them at
> the time, establishing the effect of each of them.

THIS IS IT! The last one. No pauses writing a 2Gb file now unless I do a read
midstream.

Con