From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 27 Aug 2007 18:46:12 +0000 From: Mike Travis Subject: Re: [PATCH 0/6] x86: Reduce Memory Usage and Inter-Node message traffic (v2) In-Reply-To: <20070825092434.GE16227@bingen.suse.de> Message-ID: References: <20070824222654.687510000@sgi.com> <20070825005017.GC1894@linux-os.sc.intel.com> <20070825092434.GE16227@bingen.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: "Siddha, Suresh B" , travis@sgi.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Christoph Lameter List-ID: On Sat, 25 Aug 2007, Andi Kleen wrote: > On Fri, Aug 24, 2007 at 05:50:18PM -0700, Siddha, Suresh B wrote: > > On Fri, Aug 24, 2007 at 03:26:54PM -0700, travis@sgi.com wrote: > > > Previous Intro: > > > > Thanks for doing this. > > > > > In x86_64 and i386 architectures most arrays that are sized > > > using NR_CPUS lay in local memory on node 0. Not only will most > > > (99%?) of the systems not use all the slots in these arrays, > > > particularly when NR_CPUS is increased to accommodate future > > > very high cpu count systems, but a number of cache lines are > > > passed unnecessarily on the system bus when these arrays are > > > referenced by cpus on other nodes. > > > > Can we move cpuinfo_x86 also to per cpu area? Though critical run > > I worry how much impact that would be? boot_cpu_data is quite > widely used. > I looked at this and it would be a big memory savings. But I haven't yet analyzed the various accesses to verify that we can cleanly move the structure, and that we don't suffer a bunch of tlb misses because accesses are primarily from node 0. More info soon. Thanks, Mike -- 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: email@kvack.org