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From: Thomas Gleixner <tglx@linutronix.de>
To: Chen Gang <gang.chen@asianux.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kernel/softirq.c: delete 'while' looping to improve a little performance and beautify code
Date: Mon, 10 Jun 2013 16:15:24 +0200 (CEST)	[thread overview]
Message-ID: <alpine.LFD.2.02.1306101613200.22970@ionos> (raw)
In-Reply-To: <51B4755B.4020205@asianux.com>

On Sun, 9 Jun 2013, Chen Gang wrote:
> After finish the internal 'while', need not test TASKLET_STATE_SCHED
> again, so looping back to outside 'while' is only for set_bit().
> 
> When use 'if' and set_bit() instead of 'while', it will save at least
> one running conditional instruction, and also will be clearer for readers
> (although the binary size will be a little bigger).

And by doing that you break the atomicity of test_and_set_bit. There
is a good reason why this is an atomic operation and why the code is
written as is.
 
> The related patch is "1da177e Linux-2.6.12-rc2"

How is that patch related to the problem?

Thanks

	tglx

  parent reply	other threads:[~2013-06-10 14:16 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-09 12:30 Chen Gang
2013-06-10 12:25 ` Paul E. McKenney
2013-06-13  2:08   ` Chen Gang
2013-06-10 14:15 ` Thomas Gleixner [this message]
2013-06-13  2:10   ` Chen Gang

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