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Date:   Thu, 5 May 2022 17:09:52 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc:     Christoph Hellwig <hch@lst.de>, David Sterba <dsterba@suse.com>,
        Josef Bacik <josef@toxicpanda.com>, Qu Wenruo <wqu@suse.com>,
        linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 08/10] btrfs: remove btrfs_end_io_wq
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On Thu, May 05, 2022 at 10:34:34AM +0800, Qu Wenruo wrote:
> I did a quick search on other fses, it looks like it's a common pratice
> to queue the work into the workqueue when the last one finished, other
> than making everything happen in workqueue.

Yes.  It is a lot more efficient as queing up lots of items tends to
cause quite some overhead, also due to the dynamic threadpool of the
workqueue.  XFS goes even futher and adds many bios to list at
completion time to be able to batch them up for the workqueue based
completions.