From: Jan Kara <jack@suse.cz>
To: Jens Axboe <axboe@fb.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org
Subject: Re: [PATCH 4/9] writeback: track if we're sleeping on progress in balance_dirty_pages()
Date: Wed, 13 Apr 2016 15:08:46 +0200 [thread overview]
Message-ID: <20160413130846.GA23550@quack2.suse.cz> (raw)
In-Reply-To: <1459350477-16404-5-git-send-email-axboe@fb.com>
On Wed 30-03-16 09:07:52, Jens Axboe wrote:
> Note in the bdi_writeback structure if a task is currently being
> limited in balance_dirty_pages(), waiting for writeback to
> proceed.
...
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 11ff8f758631..15e696bc5d14 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -1746,7 +1746,9 @@ pause:
> pause,
> start_time);
> __set_current_state(TASK_KILLABLE);
> + wb->dirty_sleeping = 1;
> io_schedule_timeout(pause);
> + wb->dirty_sleeping = 0;
Huh, but wb->dirty_sleeping is shared by all the processes in the system.
So this is seriously racy, isn't it? You rather need a counter for this to
work.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2016-04-13 13:08 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 15:07 [PATCHSET v3][RFC] Make background writeback not suck Jens Axboe
2016-03-30 15:07 ` [PATCH 1/9] writeback: propagate the various reasons for writeback Jens Axboe
2016-03-30 15:07 ` [PATCH 2/9] writeback: add wbc_to_write() Jens Axboe
2016-03-30 15:07 ` [PATCH 3/9] writeback: use WRITE_SYNC for reclaim or sync writeback Jens Axboe
2016-03-30 15:07 ` [PATCH 4/9] writeback: track if we're sleeping on progress in balance_dirty_pages() Jens Axboe
2016-04-13 13:08 ` Jan Kara [this message]
2016-04-13 14:20 ` Jens Axboe
2016-03-30 15:07 ` [PATCH 5/9] block: add ability to flag write back caching on a device Jens Axboe
2016-03-30 15:42 ` Christoph Hellwig
2016-03-30 15:46 ` Jens Axboe
2016-03-30 16:23 ` Jens Axboe
2016-03-30 17:29 ` Christoph Hellwig
2016-03-30 15:07 ` [PATCH 6/9] sd: inform block layer of write cache state Jens Axboe
2016-03-30 15:07 ` [PATCH 7/9] NVMe: " Jens Axboe
2016-03-30 15:07 ` [PATCH 8/9] block: add code to track actual device queue depth Jens Axboe
2016-03-30 15:07 ` [PATCH 9/9] writeback: throttle buffered writeback Jens Axboe
2016-03-31 8:24 ` [PATCHSET v3][RFC] Make background writeback not suck Dave Chinner
2016-03-31 14:29 ` Jens Axboe
2016-03-31 16:21 ` Jens Axboe
2016-04-01 0:56 ` Dave Chinner
2016-04-01 3:29 ` Jens Axboe
2016-04-01 3:33 ` Jens Axboe
2016-04-01 3:39 ` Jens Axboe
2016-04-01 6:16 ` Dave Chinner
2016-04-01 14:33 ` Jens Axboe
2016-04-01 5:04 ` Dave Chinner
2016-04-01 0:46 ` Dave Chinner
2016-04-01 3:25 ` Jens Axboe
2016-04-01 6:27 ` Dave Chinner
2016-04-01 14:34 ` Jens Axboe
2016-03-31 22:09 ` Holger Hoffstätte
2016-04-01 1:01 ` Dave Chinner
2016-04-01 16:58 ` Holger Hoffstätte
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