From mboxrd@z Thu Jan 1 00:00:00 1970 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Subject: RE: [RFC/PATCH] pfn_valid() more generic : arch independent part[0/2] Date: Wed, 6 Oct 2004 22:22:20 -0700 Message-ID: From: "Luck, Tony" Sender: owner-linux-mm@kvack.org Return-Path: To: Hiroyuki KAMEZAWA , "Martin J. Bligh" Cc: LinuxIA64 , linux-mm List-ID: >Because pfn_valid() often returns 0 in inner loop of free_pages_bulk(), >I want to avoid page fault caused by using get_user() in pfn_valid(). How often? Surely this is only a problem at the edges of blocks of memory? I suppose it depends on whether your discontig memory appears in blocks much smaller than MAXORDER. But even there it should only be an issue coalescing buddies that are bigger than the granule size (since all of the pages in a granule on ia64 are guaranteed to exist, the buddy of any page must also exist). Do you have some data to show that this is a problem. -Tony -- 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