lkml.org 
[lkml]   [2012]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 1/3] sysfs: Compact sysfs_dirent s_flags into a byte.
Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:

> 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?

The next patch stuffs an 8bit nlink in the hole. I was making room so
we don't have to grow sysfs_dirent.

Eric


\
 
 \ /
  Last update: 2012-03-09 03:49    [W:0.100 / U:0.324 seconds]
©2003-2014 Jasper Spaans. Advertise on this site