From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 19 Nov 2004 19:46:10 -0600 From: Robin Holt Subject: Re: another approach to rss : sloppy rss Message-ID: <20041120014610.GA20576@lnx-holt.americas.sgi.com> References: <419D47E6.8010409@yahoo.com.au> <419D4EC7.6020100@yahoo.com.au> <419D8C07.9040606@yahoo.com.au> <20041119195721.GA2203@lnx-holt.americas.sgi.com> <419E9CC1.8060503@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <419E9CC1.8060503@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Robin Holt , Christoph Lameter , Hugh Dickins , Benjamin Herrenschmidt , linux-mm@kvack.org, linux-ia64@vger.kernel.org List-ID: On Sat, Nov 20, 2004 at 12:24:17PM +1100, Nick Piggin wrote: > Well, you still need to put those counters on seperate cachelines, so you > still need to pad them out quite a lot. Then as they are shared, you _still_ > need to make them atomic, and they'll still be bouncing around too. > > Linus' idea of a per-thread 'pages_in - pages_out' counter may prove to be > just the right solution though. I can go with either solution. Not sure how many cpus we can group together before the cacheline becomes so hot that we need to fan them out. I have a gut feeling it is alot. On the 2.4 kernel which SGI put together, we just changed rss to an atomic and ensured it was in a seperate cacheline from the locks and performance was more than adequate. I realize a lot has changed since 2.4, but the concepts are similar. Just my 2 cents, 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