Messages in this thread | | | Date | Thu, 06 Jan 2005 15:35:32 +1100 | From | Nick Piggin <> | Subject | Re: [PATCH][5/?] count writeback pages in nr_scanned |
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Andrew Morton wrote: > Nick Piggin <nickpiggin@yahoo.com.au> wrote: > >>>I suspect something might still be broken. It may take a few >>>days of continuous testing to trigger the bug, though ... >>> >> >>It is possible to be those blk_congestion_wait paths, because >>the queue simply won't be congested. So doing io_schedule_timeout >>might help. > > > If the queue is not congested, blk_congestion_wait() will still sleep. See > freed_request(). >
Hmm... doesn't look like it to me:
if (rl->count[rw] < queue_congestion_off_threshold(q)) clear_queue_congested(q, rw);
And clear_queue_congested does an unconditional wakeup (if there is someone sleeping on the congestion queue).
> >>I wonder if reducing the size of the write queue in CFQ would help >>too? IIRC, it only really wants a huge read queue. > > > Surely it will help - but we need to be able to handle the situation > because memory can still become full of PageWriteback pages if there are > many disks. >
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