From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jiri Slaby <jslaby@suse.cz>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jiri Slaby <jirislaby@gmail.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
LKML <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Maciej Rutecki <maciej.rutecki@gmail.com>
Subject: Re: [PATCH 1/3] sysfs: Compact sysfs_dirent s_flags into a byte.
Date: Thu, 8 Mar 2012 14:28:43 -0800 [thread overview]
Message-ID: <20120308222843.GB32001@kroah.com> (raw)
In-Reply-To: <m1r4x2wzdt.fsf_-_@fess.ebiederm.org>
On Thu, Mar 08, 2012 at 01:34:22PM -0800, Eric W. Biederman wrote:
>
> In an effort to keep sysfs_dirent small used the smallest
> basic type I can for sysfs s_flags.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
> ---
> fs/sysfs/sysfs.h | 10 +++++-----
> 1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
> index 6289a00..c76c932 100644
> --- a/fs/sysfs/sysfs.h
> +++ b/fs/sysfs/sysfs.h
> @@ -76,7 +76,7 @@ struct sysfs_dirent {
> struct sysfs_elem_bin_attr s_bin_attr;
> };
>
> - unsigned short s_flags;
> + unsigned char s_flags;
> umode_t s_mode;
> unsigned int s_ino;
> struct sysfs_inode_attrs *s_iattr;
Are you sure this saved you any real space here? Have you use pahole (I
think that's the tool name) to determine if there are holes in the
structure? Given that you moved this to a smaller variable, yet there
are pointers later on, odds are nothing changed at all overall.
Verification would be good to have, to see if this work was really worth
it, right?
thanks,
greg k-h
next prev parent reply other threads:[~2012-03-08 22:28 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-30 21:56 sysfs regression: wrong link counts Jiri Slaby
2012-01-30 22:06 ` Greg KH
2012-01-30 22:10 ` Alan Cox
2012-01-30 22:27 ` Greg KH
2012-01-30 22:43 ` Al Viro
2012-01-30 22:56 ` Al Viro
2012-01-31 1:27 ` Eric W. Biederman
2012-01-31 10:48 ` Jiri Slaby
2012-01-31 12:44 ` Eric W. Biederman
2012-01-31 16:45 ` Linus Torvalds
2012-01-31 19:18 ` Al Viro
2012-02-01 5:06 ` Eric W. Biederman
2012-02-01 22:21 ` [PATCH] sysfs: Optionally count subdirectories to support buggy applications Eric W. Biederman
2012-02-01 22:24 ` Greg Kroah-Hartman
2012-02-01 22:44 ` Eric W. Biederman
2012-02-01 22:49 ` Greg Kroah-Hartman
2012-02-01 22:31 ` Dave Jones
2012-02-01 22:35 ` Jiri Slaby
2012-02-01 23:15 ` Linus Torvalds
2012-02-01 23:18 ` Linus Torvalds
2012-02-02 1:22 ` Al Viro
2012-02-02 21:24 ` [RFC] killing boilerplate checks in ->link/->mkdir/->rename Al Viro
2012-02-02 23:46 ` Linus Torvalds
2012-02-03 1:16 ` Al Viro
2012-02-03 1:45 ` Al Viro
2012-02-03 2:00 ` Linus Torvalds
2012-02-03 14:57 ` Chris Mason
2012-02-03 17:08 ` Al Viro
2012-02-03 19:34 ` Artem Bityutskiy
2012-02-06 8:50 ` Artem Bityutskiy
2012-02-06 13:56 ` Al Viro
2012-02-06 17:05 ` Artem Bityutskiy
2012-02-06 17:11 ` Al Viro
2012-02-07 7:21 ` Artem Bityutskiy
2012-02-06 22:49 ` Dave Chinner
2012-02-03 8:25 ` Andreas Dilger
2012-02-03 17:03 ` Al Viro
2012-02-04 7:42 ` Andreas Dilger
2012-03-05 13:30 ` [PATCH] sysfs: Optionally count subdirectories to support buggy applications Jiri Slaby
2012-03-05 16:09 ` Greg Kroah-Hartman
2012-03-05 16:47 ` Linus Torvalds
2012-03-08 21:05 ` Greg Kroah-Hartman
2012-03-08 22:18 ` Eric W. Biederman
2012-03-08 23:40 ` Linus Torvalds
2012-03-08 21:28 ` Eric W. Biederman
2012-03-08 21:34 ` [PATCH 1/3] sysfs: Compact sysfs_dirent s_flags into a byte Eric W. Biederman
2012-03-08 21:36 ` [PATCH 2/3] sysfs: Maintain usable nlink directory counts Eric W. Biederman
2012-03-08 21:37 ` [PATCH 3/3] sysfs: Remove SYSFS_FLAG_REMOVED and use sd->s_nlink == 0 instead Eric W. Biederman
2012-03-09 3:40 ` Linus Torvalds
2012-03-08 22:28 ` Greg Kroah-Hartman [this message]
2012-03-09 2:49 ` [PATCH 1/3] sysfs: Compact sysfs_dirent s_flags into a byte Eric W. Biederman
2012-01-31 3:45 ` sysfs regression: wrong link counts Eric W. Biederman
2012-01-31 11:54 ` Alan Cox
2012-01-30 22:52 ` Kay Sievers
2012-01-31 10:41 ` network regression: cannot rename netdev twice Jiri Slaby
2012-01-31 10:52 ` Kay Sievers
2012-01-31 11:00 ` Jiri Slaby
2012-01-31 11:13 ` Kay Sievers
2012-01-31 11:17 ` Jiri Slaby
2012-01-31 11:58 ` Kay Sievers
2012-01-31 14:18 ` Eric W. Biederman
2012-01-31 14:40 ` [PATCH] sysfs: Update the name hash when renaming sysfs entries Eric W. Biederman
2012-01-31 14:41 ` Jiri Slaby
2012-01-31 14:55 ` Greg KH
2012-02-04 2:14 ` network regression: cannot rename netdev twice Henrique de Moraes Holschuh
2012-02-06 20:03 ` Kay Sievers
2012-02-08 2:00 ` Henrique de Moraes Holschuh
2012-02-08 3:50 ` Kay Sievers
2012-02-08 6:42 ` Valdis.Kletnieks
2012-02-08 10:57 ` Kay Sievers
2012-02-08 20:06 ` Valdis.Kletnieks
2012-02-08 20:27 ` Stephen Hemminger
2012-02-08 23:48 ` Kay Sievers
2012-01-31 1:32 ` sysfs regression: wrong link counts Eric W. Biederman
2012-02-01 18:29 ` Maciej Rutecki
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