From mboxrd@z Thu Jan 1 00:00:00 1970 From: dhylands@gmail.com (Dave Hylands) Date: Tue, 21 Jun 2011 06:23:34 -0700 Subject: Question about page count In-Reply-To: References: Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org Hey Mulyadi, On Mon, Jun 20, 2011 at 10:15 PM, Mulyadi Santosa wrote: ...snip... > looking at how page_count implemented, it checks whether the related > page is gonna be reclaimed or a compound page (not sure what it is). > If so, returns the first page of that "page". On the ARM, you can setup the MMU to map 1Mb regions or 4Kb regions. A 1 Mb region only goes through the top level of the MMU, whereas a 4K page has to go through 2 levesl, so accessing pages through the 1 Mb mapping is faster. I believe (I'm not 100% sure) that the 256 x 4K pages that make up the 1Mb region are a compound page. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com