From: Omar Sandoval <osandov@osandov.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Omar Sandoval <osandov@fb.com>
Subject: Re: [PATCH] blk-mq: fix sbitmap ws_active for shared tags
Date: Mon, 25 Mar 2019 11:56:35 -0700 [thread overview]
Message-ID: <20190325185635.GF5826@vader> (raw)
In-Reply-To: <c0d3f0c8-a5d7-19dd-7b7f-1d4f860c425b@kernel.dk>
On Mon, Mar 25, 2019 at 10:22:50AM -0600, Jens Axboe wrote:
> We now wrap sbitmap waitqueues in an active counter, so we can avoid
> iterating wakeups unless we have waiters there. This works as long as
> everyone that's manipulating the waitqueues use the proper helpers. For
> the tag wait case for shared tags, however, we add ourselves to the
> waitqueue without incrementing/decrementing the ->ws_active count. This
> means that wakeups can take a long time to happen.
>
> Fix this by manually doing the inc/dec as needed for the wait queue
> handling.
>
> Fixes: 5d2ee7122c73 ("sbitmap: optimize wakeup check")
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Can this use the helpers we added in 9f6b7ef6c3eb ("sbitmap: add helpers
for add/del wait queue handling")?
next prev parent reply other threads:[~2019-03-25 18:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 16:22 [PATCH] blk-mq: fix sbitmap ws_active for shared tags Jens Axboe
2019-03-25 16:39 ` Bart Van Assche
2019-03-25 16:42 ` Jens Axboe
2019-03-25 18:56 ` Omar Sandoval [this message]
2019-03-25 18:58 ` Jens Axboe
2019-03-25 19:04 ` Omar Sandoval
2019-03-25 19:05 ` Jens Axboe
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