From: hejianet <hejianet@gmail.com>
To: Brian Foster <bfoster@redhat.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] libxfs: Optimize the loop for xfs_bitmap_empty
Date: Wed, 11 Nov 2015 14:37:51 +0800 [thread overview]
Message-ID: <5642E23F.6050009@gmail.com> (raw)
In-Reply-To: <20151110125403.GC21670@bfoster.bfoster>
Hi Brian
Thanks, I will resend the patch V2
B.R.
Justin
在 11/10/15 8:54 PM, Brian Foster 写道:
> On Mon, Nov 09, 2015 at 10:31:22PM +0800, Jia He wrote:
>> If there is any non zero bit in a long bitmap, it can jump out of the for
>> loop and finish the function as soon as possible.
>>
>> Signed-off-by: Jia He <hejianet@gmail.com>
>> Cc: Dave Chinner <david@fromorbit.com>
>> Cc: Brian Foster <bfoster@redhat.com>
>> ---
>> fs/xfs/libxfs/xfs_bit.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/fs/xfs/libxfs/xfs_bit.c b/fs/xfs/libxfs/xfs_bit.c
>> index 0e8885a..84614b0 100644
>> --- a/fs/xfs/libxfs/xfs_bit.c
>> +++ b/fs/xfs/libxfs/xfs_bit.c
>> @@ -36,6 +36,8 @@ xfs_bitmap_empty(uint *map, uint size)
>>
>> for (i = 0; i < size; i++) {
>> ret |= map[i];
>> + if (ret != 0)
>> + return 0;
>> }
>>
> Seems Ok to me, but if we're going to do this, why not just kill ret
> entirely? For example, check 'if (map[i] != 0) return 0;' in the loop
> and unconditionally return 1 if we make it to the end.
>
> Brian
>
>> return (ret == 0);
>> --
>> 2.5.0
>>
>> _______________________________________________
>> xfs mailing list
>> xfs@oss.sgi.com
>> http://oss.sgi.com/mailman/listinfo/xfs
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next prev parent reply other threads:[~2015-11-11 6:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-09 14:31 [PATCH] libxfs: Optimize the loop for xfs_bitmap_empty Jia He
2015-11-10 12:54 ` Brian Foster
2015-11-11 6:37 ` hejianet [this message]
2015-11-11 7:49 ` [PATCH v2] " Jia He
2015-11-11 12:48 ` Brian Foster
2015-12-16 3:04 ` hejianet
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