linux-kernel - RE: [f2fs-dev] [PATCH] f2fs: optimize __find_rev_next

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Message-id: <022201d11d36$17f24d50$47d6e7f0$@samsung.com>
Date:	Thu, 12 Nov 2015 18:36:29 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	'Fan Li' <fanofcode.li@...sung.com>,
	'Jaegeuk Kim' <jaegeuk@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: RE: [f2fs-dev]  [PATCH] f2fs: optimize __find_rev_next_bit

Hi Fan,

> -----Original Message-----
> From: Fan Li [mailto:fanofcode.li@...sung.com]
> Sent: Thursday, November 12, 2015 8:43 AM
> To: 'Jaegeuk Kim'
> Cc: linux-kernel@...r.kernel.org; linux-f2fs-devel@...ts.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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