From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 22 Apr 2003 07:32:36 -0700 From: "Martin J. Bligh" Subject: Re: objrmap and vmtruncate Message-ID: <171070000.1051021955@[10.10.2.4]> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar , Andrew Morton Cc: Andrea Arcangeli , mingo@elte.hu, hugh@veritas.com, dmccr@us.ibm.com, Linus Torvalds , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: > It also makes it easy to calculate the overhead of the pte chains: twice > the amount of pagetable overhead. Ie. with 32-bit pte's it's +8 bytes > overhead, or +0.2% of RAM overhead per mapped page, using a 4K page. With > 64-bit ptes on 32-bit platforms (PAE), the overhead is still 8 bytes. On > 64-bit platforms using 8K pages the overhead is still +0.2% of RAM, in > additionl to the 0.1% of RAM overhead for the pte itself. The worst-case > is 64-bit platforms with a 4K pagesize, there the overhead is +0.4% of > RAM, in addition to the 0.2% overhead caused by the pte itself. Oh, BTW. You're assuming no sharing of any pages in the above. Look what happens if 1000 processes share the same page ... M. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org