On Tue, 14 Feb 2012 21:18:12 +0800
Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
>
> --- linux.orig/include/linux/backing-dev.h 2012-02-14 19:43:06.000000000 +0800
> +++ linux/include/linux/backing-dev.h 2012-02-14 19:49:26.000000000 +0800
> @@ -304,6 +304,8 @@ void clear_bdi_congested(struct backing_
> void set_bdi_congested(struct backing_dev_info *bdi, int sync);
> long congestion_wait(int sync, long timeout);
> long wait_iff_congested(struct zone *zone, int sync, long timeout);
> +long reclaim_wait(long timeout);
> +void reclaim_rotated(void);
>
> static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
> {
> --- linux.orig/mm/backing-dev.c 2012-02-14 19:26:15.000000000 +0800
> +++ linux/mm/backing-dev.c 2012-02-14 20:09:45.000000000 +0800
> @@ -873,3 +873,38 @@ out:
> return ret;
> }
> EXPORT_SYMBOL(wait_iff_congested);
> +
> +static DECLARE_WAIT_QUEUE_HEAD(reclaim_wqh);
> +
> +/**
> + * reclaim_wait - wait for some pages being rotated to the LRU tail
> + * @timeout: timeout in jiffies
> + *
> + * Wait until @timeout, or when some (typically PG_reclaim under writeback)
> + * pages rotated to the LRU so that page reclaim can make progress.
> + */
> +long reclaim_wait(long timeout)
> +{
> + long ret;
> + unsigned long start = jiffies;
> + DEFINE_WAIT(wait);
> +
> + prepare_to_wait(&reclaim_wqh, &wait, TASK_KILLABLE);
> + ret = io_schedule_timeout(timeout);
> + finish_wait(&reclaim_wqh, &wait);
> +
> + trace_writeback_reclaim_wait(jiffies_to_usecs(timeout),
> + jiffies_to_usecs(jiffies - start));
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(reclaim_wait);
> +
> +void reclaim_rotated()
> +{
> + wait_queue_head_t *wqh = &reclaim_wqh;
> +
> + if (waitqueue_active(wqh))
> + wake_up(wqh);
> +}
> +
Thank you.
I like this approach. A nitpick is that this may wake up all waiters
in the system when a memcg is rotated.
How about wait_event() + condition by bitmap (using per memcg unique IDs.) ?
Thanks,
-Kame
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