From: Chao Yu <chao2.yu@samsung.com>
To: "'Fan Li'" <fanofcode.li@samsung.com>,
        "'Jaegeuk Kim'" <jaegeuk@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
References: <000001d11ce3$2f947f30$8ebd7d90$@samsung.com>
In-reply-to: <000001d11ce3$2f947f30$8ebd7d90$@samsung.com>
Subject: RE: [f2fs-dev]  [PATCH] f2fs: optimize __find_rev_next_bit
Date: Thu, 12 Nov 2015 18:36:29 +0800
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Hi Fan,

> -----Original Message-----
> From: Fan Li [mailto:fanofcode.li@samsung.com]
> Sent: Thursday, November 12, 2015 8:43 AM
> To: 'Jaegeuk Kim'
> Cc: linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net
> Subject: [f2fs-dev] [PATCH] f2fs: optimize __find_rev_next_bit
> 
> 1. Skip __reverse_ulong if the bitmap is empty.
> 2. Reduce branches and codes.
> According to my test, the performance of this new version is 5% higher on
> an empty bitmap of 64bytes, and remains about the same in the worst scenario.

Good catch!

IMO, it's better to optimize __find_rev_next_{,zero}bit together. :)

Thanks,


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