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List:       linux-mm
Subject:    Re: Kernel 2.6.8.1: swap storm of death - nr_requests > 1024 on swap partition
From:       William Lee Irwin III <wli () holomorphy ! com>
Date:       2004-08-29 22:17:57
Message-ID: 20040829221757.GA5492 () holomorphy ! com
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Jens Axboe <axboe@suse.de> wrote:
>>  Why you do see a difference is that when ->max_queued isn't valid, you
>>  end up block a lot more in get_request_wait() because cfq_may_queue will
>>  disallow you to queue a lot more than with the patch. Since other io
>>  schedulers don't have these sort of checks, they behave like CFQ does
>>  with the bug in blk_init_queue() fixed.

On Sun, Aug 29, 2004 at 01:59:17PM -0700, Andrew Morton wrote:
> The changlog wasn't that detailed ;)
> But yes, it's the large nr_requests which is tripping up swapout.  I'm
> assuming that when a process exits with its anonymous memory still under
> swap I/O we're forgetting to actually free the pages when the I/O
> completes.  So we end up with a ton of zero-ref swapcache pages on the LRU.
> I assume.   Something odd's happening, that's for sure.

Maybe we need to be checking for this in end_swap_bio_write() or
rotate_reclaimable_page()?


-- wli
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