From mboxrd@z Thu Jan  1 00:00:00 1970
From: cl@linux.com (Christoph Lameter)
Date: Thu, 30 Apr 2009 11:44:54 -0400 (EDT)
Subject: [ltt-dev] [PATCH] Fix dirty page accounting in
 redirty_page_for_writepage()
In-Reply-To: <20090430154255.GA3714@elte.hu>
References: <20090430024303.GB19875@Krystal>
	<alpine.DEB.1.10.0904300921290.22262@qirst.com>
	<20090430133859.GB8329@elte.hu>
	<alpine.DEB.1.10.0904300938220.22262@qirst.com>
	<20090430141446.GD14696@elte.hu>
	<alpine.DEB.1.10.0904301013110.14178@qirst.com>
	<20090430143819.GF14696@elte.hu>
	<alpine.DEB.1.10.0904301042170.4028@qirst.com>
	<20090430150142.GC20580@elte.hu>
	<alpine.DEB.1.10.0904301114440.4028@qirst.com>
	<20090430154255.GA3714@elte.hu>
Message-ID: <alpine.DEB.1.10.0904301142140.4028@qirst.com>

On Thu, 30 Apr 2009, Ingo Molnar wrote:

> nice. Do these all get called with irqs off, all the time?

In most cases yes. The VMstat patch includes an example were we may not
care too much about a event counter missing a beat once in a while for
platforms not supporting atomic per cpu ops. I know this affects IA64. The
cost of an atomic operations for an event counter update (which would have
avoided the potential of a concurrent update) was not justifiable.