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Subject: Re: [PATCH] bcache: Optimize sysfs_hprint()
From:   Coly Li <colyli@suse.de>
In-Reply-To: <9b82413f1ca0b924cc139d945777e32dd22ffe41.1698575385.git.christophe.jaillet@wanadoo.fr>
Date:   Mon, 30 Oct 2023 15:38:08 +0800
Cc:     Kent Overstreet <kent.overstreet@gmail.com>,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
        linux-bcache@vger.kernel.org
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Message-Id: <BF96F92E-B483-4FC7-B4DB-B9D76E44D9A7@suse.de>
References: <9b82413f1ca0b924cc139d945777e32dd22ffe41.1698575385.git.christophe.jaillet@wanadoo.fr>
To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Precedence: bulk


> 2023=E5=B9=B410=E6=9C=8829=E6=97=A5 18:30=EF=BC=8CChristophe JAILLET =
<christophe.jaillet@wanadoo.fr> =E5=86=99=E9=81=93=EF=BC=9A
>=20
> The size of what is in 'buf' is already computed by bch_hprint(), so =
skip
> these bytes when calling strcat().
>=20
> This easily saves a few cycles. (should it matter)
>=20
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.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.=20

Thanks.

Coly Li

> ---
> drivers/md/bcache/sysfs.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> 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 =3D=3D &sysfs_ ## file) { \
> ssize_t ret =3D bch_hprint(buf, val); \
> - strcat(buf, "\n"); \
> + strcat(buf + ret, "\n"); \
> return ret + 1; \
> } \
> } while (0)
> --=20
> 2.34.1
>=20