From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 19 Nov 2004 18:03:06 -0800 From: William Lee Irwin III Subject: Re: page fault scalability patch V11 [0/7]: overview Message-ID: <20041120020306.GA2714@holomorphy.com> References: <419D581F.2080302@yahoo.com.au> <419D5E09.20805@yahoo.com.au> <1100848068.25520.49.camel@gaston> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Christoph Lameter , akpm@osdl.org, Benjamin Herrenschmidt , Nick Piggin , Hugh Dickins , linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org List-ID: On Fri, Nov 19, 2004 at 11:59:03AM -0800, Linus Torvalds wrote: > You could also make "rss" be a _signed_ integer per-thread. > When unmapping a page, you decrement one of the threads that shares the mm > (doesn't matter which - which is why the per-thread rss may go negative), > and when mapping a page you increment it. > Then, anybody who actually wants a global rss can just iterate over > threads and add it all up. If you do it under the mmap_sem, it's stable, > and if you do it outside the mmap_sem it's imprecise but stable in the > long term (ie errors never _accumulate_, like the non-atomic case will > do). > Does anybody care enough? Maybe, maybe not. It certainly sounds a hell of > a lot better than the periodic scan. Unprivileged triggers for full-tasklist scans are NMI oops material. -- wli -- 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