From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 14 Feb 2005 16:01:49 -0600 From: Robin Holt Subject: Re: [RFC 2.6.11-rc2-mm2 7/7] mm: manual page migration -- sys_page_migrate Message-ID: <20050214220148.GA11832@lnx-holt.americas.sgi.com> References: <20050212032535.18524.12046.26397@tomahawk.engr.sgi.com> <20050212032620.18524.15178.29731@tomahawk.engr.sgi.com> <1108242262.6154.39.camel@localhost> <20050214135221.GA20511@lnx-holt.americas.sgi.com> <1108407043.6154.49.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1108407043.6154.49.camel@localhost> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: Robin Holt , Ray Bryant , Hirokazu Takahashi , Hugh DIckins , Andrew Morton , Marcello Tosatti , Ray Bryant , linux-mm , linux-kernel List-ID: On Mon, Feb 14, 2005 at 10:50:42AM -0800, Dave Hansen wrote: > On Mon, 2005-02-14 at 07:52 -0600, Robin Holt wrote: > > The node mask is a list of allowed. This is intended to be as near > > to a one-to-one migration path as possible. > > If that's the case, it would make the kernel internals a bit simpler to > only take a "from" and "to" node, instead of those maps. You'll end up > making multiple syscalls, but that shouldn't be a problem. Then how do you handle overlapping nodes. If I am doing a 5->4, 4->3, 3->2, 2->1 shift in the memory placement and had only a from and to node, I would end up calling multiple times. This would end up in memory shifting from 5->4 on the first, 4->3 on the second, ... with the end result of all memory shifting to a single node. With the array-of-node maps, you make a single pass across the address space. This results in a clean mapping without the userspace needing to know which nodes the pages are on. On a seperate topic, I would guess the syscall time is trivial compared to the time to walk the page tables. Thanks, Robin -- 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