From: Bart Van Assche <bvanassche@acm.org>
To: "yukuai (C)" <yukuai3@huawei.com>,
axboe@kernel.dk, andriy.shevchenko@linux.intel.com,
john.garry@huawei.com, ming.lei@redhat.com
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
yi.zhang@huawei.com
Subject: Re: [PATCH -next RFC v2 8/8] sbitmap: wake up the number of threads based on required tags
Date: Mon, 11 Apr 2022 20:20:32 -0700 [thread overview]
Message-ID: <7095eedb-91a7-e8d6-f30b-91aa65de3533@acm.org> (raw)
In-Reply-To: <51aa71af-4c05-2991-5698-12014a4943d5@huawei.com>
On 4/9/22 00:01, yukuai (C) wrote:
> For the race that new threads are waited after get_wake_nr() and before
> wake_up_nr() in situation (b), I can't figure out how this can be
> problematic [ ... ]
If the atomic_dec_return() statement in __sbq_wake_up() returns a value
that is less than or equal to zero, wake_batch waiters should be woken
up or I/O will hang until sbitmap_queue_wake_all() is called. That last
function should not be called unless there is no alternative.
Thanks,
Bart.
next prev parent reply other threads:[~2022-04-12 3:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-08 7:39 [PATCH -next RFC v2 0/8] improve tag allocation under heavy load Yu Kuai
2022-04-08 7:39 ` [PATCH -next RFC v2 1/8] sbitmap: record the number of waiters for each waitqueue Yu Kuai
2022-04-08 7:39 ` [PATCH -next RFC v2 2/8] blk-mq: call 'bt_wait_ptr()' later in blk_mq_get_tag() Yu Kuai
2022-04-08 14:20 ` Bart Van Assche
2022-04-09 2:09 ` yukuai (C)
2022-04-08 7:39 ` [PATCH -next RFC v2 3/8] sbitmap: make sure waitqueues are balanced Yu Kuai
2022-04-15 6:31 ` Li, Ming
2022-04-15 7:07 ` yukuai (C)
2022-04-08 7:39 ` [PATCH -next RFC v2 4/8] blk-mq: don't preempt tag under heavy load Yu Kuai
2022-04-08 14:24 ` Bart Van Assche
2022-04-09 2:38 ` yukuai (C)
2022-04-08 7:39 ` [PATCH -next RFC v2 5/8] sbitmap: force tag preemption if free tags are sufficient Yu Kuai
2022-04-08 7:39 ` [PATCH -next RFC v2 6/8] blk-mq: force tag preemption for split bios Yu Kuai
2022-04-08 7:39 ` [PATCH -next RFC v2 7/8] blk-mq: record how many tags are needed for splited bio Yu Kuai
2022-04-08 7:39 ` [PATCH -next RFC v2 8/8] sbitmap: wake up the number of threads based on required tags Yu Kuai
2022-04-08 14:31 ` Bart Van Assche
2022-04-09 2:19 ` yukuai (C)
2022-04-08 21:13 ` Bart Van Assche
2022-04-09 2:17 ` yukuai (C)
2022-04-09 4:16 ` Bart Van Assche
2022-04-09 7:01 ` yukuai (C)
2022-04-12 3:20 ` Bart Van Assche [this message]
2022-04-08 19:10 ` [PATCH -next RFC v2 0/8] improve tag allocation under heavy load Jens Axboe
2022-04-09 2:26 ` yukuai (C)
2022-04-09 2:28 ` Jens Axboe
2022-04-09 2:34 ` yukuai (C)
2022-04-09 7:14 ` yukuai (C)
2022-04-09 21:31 ` Bart Van Assche
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