From: Jens Axboe <axboe@kernel.dk>
To: Yu Kuai <yukuai3@huawei.com>,
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 1/6] blk-mq: add a new flag 'BLK_MQ_F_NO_TAG_PREEMPTION'
Date: Tue, 29 Mar 2022 06:44:28 -0600 [thread overview]
Message-ID: <190625d8-ed84-f657-6058-2d151f6d4caa@kernel.dk> (raw)
In-Reply-To: <20220329094048.2107094-2-yukuai3@huawei.com>
On 3/29/22 3:40 AM, Yu Kuai wrote:
> Tag preemption is the default behaviour, specifically blk_mq_get_tag()
> will try to get tag unconditionally, which means a new io can preempt tag
> even if there are lots of ios that are waiting for tags.
>
> This patch introduce a new flag, prepare to disable such behaviour, in
> order to optimize io performance for large random io for HHD.
Not sure why we need a flag for this behavior. Does it ever make sense
to allow preempting waiters, jumping the queue?
--
Jens Axboe
next prev parent reply other threads:[~2022-03-29 12:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-29 9:40 [PATCH -next RFC 0/6] improve large random io for HDD Yu Kuai
2022-03-29 9:40 ` [PATCH -next RFC 1/6] blk-mq: add a new flag 'BLK_MQ_F_NO_TAG_PREEMPTION' Yu Kuai
2022-03-29 12:44 ` Jens Axboe [this message]
2022-03-30 1:18 ` yukuai (C)
2022-03-30 1:20 ` Jens Axboe
2022-03-29 9:40 ` [PATCH -next RFC 2/6] block: refactor to split bio thoroughly Yu Kuai
2022-03-29 12:46 ` Jens Axboe
2022-03-30 1:35 ` yukuai (C)
2022-03-29 13:32 ` Christoph Hellwig
2022-03-29 14:35 ` Jens Axboe
2022-03-29 14:40 ` Christoph Hellwig
2022-03-29 14:41 ` Jens Axboe
2022-03-29 14:42 ` Christoph Hellwig
2022-03-30 1:54 ` yukuai (C)
2022-03-29 9:40 ` [PATCH -next RFC 3/6] blk-mq: record how many tags are needed for splited bio Yu Kuai
2022-03-29 9:40 ` [PATCH -next RFC 4/6] sbitmap: wake up the number of threads based on required tags Yu Kuai
2022-03-29 9:40 ` [PATCH -next RFC 5/6] blk-mq: don't preempt tag expect for split bios Yu Kuai
2022-03-29 9:40 ` [PATCH -next RFC 6/6] sbitmap: force tag preemption if free tags are sufficient Yu Kuai
2022-03-29 12:53 ` [PATCH -next RFC 0/6] improve large random io for HDD Jens Axboe
2022-03-30 2:05 ` yukuai (C)
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