From: Andrew Morton <akpm@linux-foundation.org>
To: "Chanho Min" <chanho.min@lge.com>
Cc: "'Nadia Yvette Chambers'" <nyc@holomorphy.com>,
"'Jiri Kosina'" <jkosina@suse.cz>,
"'Guennadi Liakhovetski'" <lg@denx.de>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] bitmap: speedup in bitmap_find_free_region when order is 0
Date: Tue, 9 Apr 2013 13:22:02 -0700 [thread overview]
Message-ID: <20130409132202.a73a059ab2b57d47d6f1652b@linux-foundation.org> (raw)
In-Reply-To: <5163b689.64d3440a.731b.ffff9984SMTPIN_ADDED_BROKEN@mx.google.com>
On Tue, 9 Apr 2013 15:34:44 +0900 "Chanho Min" <chanho.min@lge.com> wrote:
> >It seems excessively complicated to me. Why not change
> >bitmap_find_free_region() to skip the leading all-ones words and when
> >it finds a not-all-ones word, adjust `pos' then fall into the existing
> >bit-at-a-time search?
>
> Do we need the additional 'if' inside the for loop for implementing it?
It was just a concept - there are various ways of optimizing a real
implementation. Move the code into userspace then run some
microbenchmarks.
> I thought the separation of the routine for order=0 is the way to avoid
> the impact on the existing codes and its performance.
The existing code doesn't have any performance ;) It's so darn slow
that even a minor effort here will yield large (ie order-of-magnitude)
performance improvements.
prev parent reply other threads:[~2013-04-09 20:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-09 2:44 Chanho Min
2013-04-09 3:10 ` Andrew Morton
2013-04-09 3:18 ` Joe Perches
2013-04-09 4:18 ` Andrew Morton
2013-04-09 4:27 ` checkpatch: Warn on space before semicolon Joe Perches
[not found] ` <5163b689.64d3440a.731b.ffff9984SMTPIN_ADDED_BROKEN@mx.google.com>
2013-04-09 20:22 ` Andrew Morton [this message]
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