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

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Message-ID: <ZGKY1A1q5Px64v9h@kbusch-mbp>
Date:   Mon, 15 May 2023 14:40:52 -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:
> From: Jiwei Sun <sunjw10@...ovo.com>
> 
> A soft lockup issue will be triggered when do fio test on a 448-core
> server, such as the following warning:

...

> 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.

The most recent 6.4-rc has included a significant changeset to the pool
allocator that may show a considerable difference in pool->lock timing.
It would be interesting to hear if it changes your observation with your
448-core setup. Would you be able to re-run your experiements that
produced the soft lockup with this kernel on that machine?