Re: [PATCH] backing dev unplugging

Christophe Saout
2004-03-11T12:17:36Z

Am Mi, den 10.03.2004 schrieb Jens Axboe um 13:45:

> diff -ur -X /home/axboe/cdrom/exclude /opt/kernel/linux-2.6.4-rc2-mm1/drivers/md/dm-crypt.c linux-2.6.4-rc2-mm1-plug/drivers/md/dm-crypt.c
> --- /opt/kernel/linux-2.6.4-rc2-mm1/drivers/md/dm-crypt.c 2004-03-09 13:08:48.000000000 +0100
> +++ linux-2.6.4-rc2-mm1-plug/drivers/md/dm-crypt.c 2004-03-09 15:27:36.000000000 +0100
> @@ -668,7 +668,7 @@
>
> /* out of memory -> run queues */
> if (remaining)
> - blk_run_queues();
> + blk_congestion_wait(bio_data_dir(clone), HZ/100);

Why did you change this? It was the way I wanted it.

If we were out of memory the buffers were allocated from a mempool and I
want to get it out as soon as possible. If we are OOM the write will
most likely be the VM trying to free some memory and it would be
counterproductive to wait. It is not unlikely that we are the only
writer to that disk so there's a chance that the queue is not congested.