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Date:   Mon, 27 Sep 2021 17:15:46 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Hamza Mahfooz <someguy@effective-light.com>
Cc:     linux-kernel@vger.kernel.org, Benjamin LaHaise <bcrl@kvack.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>, linux-aio@kvack.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] aio: convert active_reqs into an array
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On Mon, Sep 27, 2021 at 12:10:47PM -0400, Hamza Mahfooz wrote:
> Commit 833f4154ed56 ("aio: fold lookup_kiocb() into its sole caller")
> suggests that, the fact that active_reqs is a linked-list means aio_kiocb
> lookups in io_cancel() are inefficient. So, to get faster lookups while
> maintaining similar characteristics elsewhere, turn active_reqs into an
> array and keep track of the free indices of the array (so we know which
> indices are safe to use).

As requested last time: please explain what workload you have where
cancellation performance actually matters.