linux-kernel - Re: [PATCH v3] block: simplify blksize

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Message-ID: <a3c2674b-c2fd-9128-4ea0-0264c0fc1156@nvidia.com>
Date:   Mon, 31 Oct 2022 02:03:48 +0000
From:   Chaitanya Kulkarni <chaitanyak@...dia.com>
To:     Dawei Li <set_pte_at@...look.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>
CC:     "bvanassche@....org" <bvanassche@....org>,
        "hch@....de" <hch@....de>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] block: simplify blksize_bits() implementation

On 10/29/2022 10:20 PM, 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.
> 

do you have a quantitative date to prove that ?
Also which arch benefits the most ? is it true for all ?

> 2) Given that blksize_bits() is inline, _if_ @size is compile-time
> constant, it's possible that order_base_2() _may_ make output
> compile-time evaluated, depending on code context and compiler behavior.
> 

patches like this needs to be supported by the quantitative
data, else I've seen reviewers taking an objection ...

either way :-

Reviewed-by: Chaitanya Kulkarni <kch@...dia.com>

-ck