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Message-ID: <641c8be0-69f6-0ab5-b174-411352ed5f94@deltatee.com>
Date:   Fri, 16 Sep 2022 12:36:14 -0600
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To:     Yu Kuai <yukuai1@huaweicloud.com>, song@kernel.org,
        guoqing.jiang@linux.dev, pmenzel@molgen.mpg.de
Cc:     linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        yukuai3@huawei.com, yi.zhang@huawei.com
References: <20220916113428.774061-1-yukuai1@huaweicloud.com>
 <20220916113428.774061-4-yukuai1@huaweicloud.com>
From:   Logan Gunthorpe <logang@deltatee.com>
In-Reply-To: <20220916113428.774061-4-yukuai1@huaweicloud.com>
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Subject: Re: [PATCH v3 3/5] md/raid10: prevent unnecessary calls to wake_up()
 in fast path
Precedence: bulk


On 2022-09-16 05:34, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> Currently, wake_up() is called unconditionally in fast path such as
> raid10_make_request(), which will cause lock contention under high
> concurrency:
> 
> raid10_make_request
>  wake_up
>   __wake_up_common_lock
>    spin_lock_irqsave
> 
> Improve performance by only call wake_up() if waitqueue is not empty
> in allow_barrier() and raid10_make_request().
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Reviewed-by: Logan Gunthorpe <logang@deltatee.com>