From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx102.postini.com [74.125.245.102]) by kanga.kvack.org (Postfix) with SMTP id 588B76B007E for ; Mon, 2 Apr 2012 12:45:55 -0400 (EDT) Message-ID: <4F79D9F1.7030504@redhat.com> Date: Mon, 02 Apr 2012 12:55:13 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [RFC][PATCH 00/26] sched/numa References: <20120316144028.036474157@chello.nl> <4F670325.7080700@redhat.com> <1332155527.18960.292.camel@twins> <20120319130401.GI24602@redhat.com> <1332163591.18960.334.camel@twins> <20120319135745.GL24602@redhat.com> <4F673D73.90106@redhat.com> <20120319143002.GQ24602@redhat.com> <1332182523.18960.372.camel@twins> <4F69022D.3080300@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: Peter Zijlstra , Andrea Arcangeli , Avi Kivity , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Dan Smith , Bharata B Rao , Lee Schermerhorn , Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org On 04/02/2012 12:34 PM, Pekka Enberg wrote: > On Wed, Mar 21, 2012 at 12:18 AM, Rik van Riel wrote: >> I suspect Java and other runtimes may have issues where >> they simply do not know which thread will end up using >> which objects from the heap heavily. > > What kind of JVM workloads are you thinking of? Modern GCs use > thread-local allocation for performance reasons so I'd assume that > most of accesses are on local node. Yes, the use thread-local allocation. However, I suspect that after the memory has been allocated locally, it may quite often end up with another thread for further processing... The JVM doing the right thing only helps so much, when the Java program has no way to know about underlying things, or influence how the threads get scheduled on the JVM. Allowing us to discover which threads are accessing the same data, and figuring out what data each thread uses, could be useful for NUMA placement... I have some ideas on how to gather the information that Andrea is gathering, with less space overhead. I will try to present that idea today... -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org