linux-kernel - Re: [PATCH] nvme: add cond_resched() to nvme_complete

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Message-ID: <ZFKLxfet7qUIwScd@kbusch-mbp.dhcp.thefacebook.com>
Date:   Wed, 3 May 2023 10:28:53 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     jiweisun126@....com
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        axboe@...com, hch@....de, sagi@...mberg.me, ahuang12@...ovo.com,
        sunjw10@...ovo.com
Subject: Re: [PATCH] nvme: add cond_resched() to nvme_complete_batch()

On Tue, May 02, 2023 at 08:54:12PM +0800, jiweisun126@....com wrote:
> According to the above two logs, we can know the nvme_irq() cost too much
> time, in the above case, about 4.8 second. And we can also know that the
> main bottlenecks is in the competition for the spin lock pool->lock.

I have a fix that makes pool->lock critical section much shorter and constant
time. It was staged in mm tree for months, but mysteriously it's missing...