From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from schroedinger.engr.sgi.com (schroedinger.engr.sgi.com [150.166.1.51]) by netops-testserver-3.corp.sgi.com (Postfix) with ESMTP id 808B89088D for ; Fri, 16 Mar 2007 15:17:39 -0700 (PDT) Received: from clameter (helo=localhost) by schroedinger.engr.sgi.com with local-esmtp (Exim 3.36 #1 (Debian)) id 1HSKjz-00022n-00 for ; Fri, 16 Mar 2007 15:17:39 -0700 Date: Fri, 16 Mar 2007 15:17:39 -0700 (PDT) From: Christoph Lameter Subject: ZERO_PAGE refcounting causes cache line bouncing Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: We have issues with ZERO_PAGE refcounting causing severe cacheline bouncing. ZERO_PAGES are mapped into multiple processes running on multiple nodes. Refcounter modifications therefore have to acquire a remote exclusive cacheline. Could we somehow fix this? There are a couple of ways to do this: 1. No refcounting on reserved pages in the VM. ZERO_PAGEs are reserved and there is no point in refcounting them since they will not go away. 2. Having a percpu or pernode ZERO_PAGE? May be a simpler solution but then we still may have issues if the ZERO_PAGE gets "freed" from other processors/ nodes. -- 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: email@kvack.org