From: Joe Perches <joe@perches.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] softirq: Use ffs in __do_softirq
Date: Mon, 09 Dec 2013 10:56:46 -0800 [thread overview]
Message-ID: <1386615406.8168.16.camel@joe-AO722> (raw)
In-Reply-To: <20131209184454.GA1811@localhost.localdomain>
On Mon, 2013-12-09 at 19:44 +0100, Frederic Weisbecker wrote:
> On Sun, Nov 17, 2013 at 01:55:10AM -0800, Joe Perches wrote:
> > Possible speed improvement of the __do_softirq function by using ffs
> > instead of using a while loop with an & 1 test then single bit shift.
[]
> Perhaps using for_each_set_bit() would simplify that more?
It might simplify the appearance of the code but it
would/could expand the amount of generated code because
for_each_set_bit uses an address_of(unsigned long) and
the value tested is an unsigned int.
extra dereferences, can't be in a register, etc...
next prev parent reply other threads:[~2013-12-09 18:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-17 9:55 [PATCH 0/3] softirq: possible speedup and neatenings Joe Perches
2013-11-17 9:55 ` [PATCH 1/3] softirq: Use ffs in __do_softirq Joe Perches
2013-12-09 18:44 ` Frederic Weisbecker
2013-12-09 18:56 ` Joe Perches [this message]
2013-12-09 19:13 ` Frederic Weisbecker
2013-11-17 9:55 ` [PATCH 2/3] softirq: Convert printks to pr_<level> Joe Perches
2013-11-17 9:55 ` [PATCH 3/3] softirq: Use const char * const for softirq_to_name, whitespace neatening Joe Perches
2013-12-24 15:19 ` Wang YanQing
2013-12-24 15:27 ` Joe Perches
2013-12-09 17:22 ` [PATCH 0/3] softirq: possible speedup and neatenings Joe Perches
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