linux-kernel - Re: [PATCH v5] erofs: add per-cpu threads for decompression as an option

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Date:   Thu, 23 Feb 2023 18:29:56 +0000
From:   Eric Biggers <ebiggers@...nel.org>
To:     Gao Xiang <hsiangkao@...ux.alibaba.com>
Cc:     linux-erofs@...ts.ozlabs.org, Chao Yu <chao@...nel.org>,
        Yue Hu <huyue2@...lpad.com>,
        Jeffle Xu <jefflexu@...ux.alibaba.com>,
        Sandeep Dhavale <dhavale@...gle.com>, kernel-team@...roid.com,
        LKML <linux-kernel@...r.kernel.org>,
        Nathan Huckleberry <nhuck@...gle.com>
Subject: Re: [PATCH v5] erofs: add per-cpu threads for decompression as an
 option

Hi,

On Wed, Feb 08, 2023 at 05:33:22PM +0800, Gao Xiang wrote:
> From: Sandeep Dhavale <dhavale@...gle.com>
> 
> Using per-cpu thread pool we can reduce the scheduling latency compared
> to workqueue implementation. With this patch scheduling latency and
> variation is reduced as per-cpu threads are high priority kthread_workers.
> 
> The results were evaluated on arm64 Android devices running 5.10 kernel.

I see that this patch was upstreamed.  Meanwhile, commit c25da5b7baf1d
("dm verity: stop using WQ_UNBOUND for verify_wq") was also upstreamed.

Why is this more complex solution better than simply removing WQ_UNBOUND?

- Eric