From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Date: Sun, 27 Mar 2005 17:12:20 +0000 Subject: Re: [PATCH] add a clear_pages function to clear pages of higher order Message-Id: <20050327171220.GA18506@muc.de> List-Id: References: <200503111008.12134.vda@port.imtp.ilyichevsk.odessa.ua> <200503181154.37414.vda@port.imtp.ilyichevsk.odessa.ua> <20050318192808.GB38053@muc.de> <16963.2075.713737.485070@napali.hpl.hp.com> In-Reply-To: <16963.2075.713737.485070@napali.hpl.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: davidm@hpl.hp.com Cc: Christoph Lameter , Denis Vlasenko , Dave Hansen , Andrew Morton , Linux Kernel Mailing List , Mel Gorman , linux-ia64@vger.kernel.org, Jens.Maurer@gmx.net > Clearly, if the CPU that's clearing the page is likely to use that > same page soon after, it'd be useful to use temporal stores. That is always the case in the current code (without Christophers pre cleaning daemon). The page fault handler clears and user space is guaranteed to need at least one cacheline from the fresh page because it just did a page fault on it. With non temporal stores you guarantee at least one hard cache miss directly after the return to user space. I suspect even with precleaning the average time from cleaning to use will be quite short. -Andi