linux-kernel - Re: [PATCH] bcache: Optimize sysfs

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Message-Id: <BF96F92E-B483-4FC7-B4DB-B9D76E44D9A7@suse.de>
Date:   Mon, 30 Oct 2023 15:38:08 +0800
From:   Coly Li <colyli@...e.de>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Kent Overstreet <kent.overstreet@...il.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-bcache@...r.kernel.org
Subject: Re: [PATCH] bcache: Optimize sysfs_hprint()



> 2023年10月29日 18:30，Christophe JAILLET <christophe.jaillet@...adoo.fr> 写道：
> 
> The size of what is in 'buf' is already computed by bch_hprint(), so skip
> these bytes when calling strcat().
> 
> This easily saves a few cycles. (should it matter)
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>

Your change does save several cpu cycles, but hurts the readability. This is not hot code path, just let strcat to do what it was designed for. 

Thanks.

Coly Li

> ---
> drivers/md/bcache/sysfs.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/bcache/sysfs.h b/drivers/md/bcache/sysfs.h
> index 65b8bd975ab1..798bcbeab0bb 100644
> --- a/drivers/md/bcache/sysfs.h
> +++ b/drivers/md/bcache/sysfs.h
> @@ -78,7 +78,7 @@ do { \
> do { \
> if (attr == &sysfs_ ## file) { \
> ssize_t ret = bch_hprint(buf, val); \
> - strcat(buf, "\n"); \
> + strcat(buf + ret, "\n"); \
> return ret + 1; \
> } \
> } while (0)
> -- 
> 2.34.1
>