From: Jens Axboe <axboe@kernel.dk>
To: Bart Van Assche <bvanassche@acm.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Cc: Omar Sandoval <osandov@fb.com>
Subject: Re: [PATCH] blk-mq: fix sbitmap ws_active for shared tags
Date: Mon, 25 Mar 2019 10:42:41 -0600 [thread overview]
Message-ID: <0ef38015-d57c-fdbd-6c1e-6cf2ceec3ec4@kernel.dk> (raw)
In-Reply-To: <1553531987.118779.9.camel@acm.org>
On 3/25/19 10:39 AM, Bart Van Assche wrote:
> On Mon, 2019-03-25 at 10:22 -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>
>
> Hi Jens,
>
> Since commit 5d2ee7122c73 went upstream in kernel v5.0, does this patch need
> a "Cc: stable" tag?
I guess it does, I'll add it.
--
Jens Axboe
next prev parent reply other threads:[~2019-03-25 16:42 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 [this message]
2019-03-25 18:56 ` Omar Sandoval
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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