linux-kernel - Re: [PATCH] block: simplify blksize

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Message-ID: <Y1lhmzQ9L2vxJzns@kbusch-mbp.dhcp.thefacebook.com>
Date:   Wed, 26 Oct 2022 10:34:35 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     Dawei Li <set_pte_at@...look.com>, axboe@...nel.dk, hch@....de,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block: simplify blksize_bits() implementation

On Wed, Oct 26, 2022 at 09:29:21AM -0700, Bart Van Assche wrote:
> On 10/26/22 08:14, Dawei Li wrote:
> > Convert current looping-based implementation into bit operation,
> > which can bring improvement for:
> > 
> > 1) bitops is more efficient for its arch-level optimization.
> 
> As far as I know blksize_bits() is not used in the hot path so performance
> of this function is not critical.

blksize_bits() is used on every IO going through iomap_dio_bio_iter(),
though the usage there is completely unnecessary and can be removed.