Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752051Ab3FZOtJ (ORCPT ); Wed, 26 Jun 2013 10:49:09 -0400 Received: from relay2.sgi.com ([192.48.179.30]:37813 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750729Ab3FZOtH (ORCPT ); Wed, 26 Jun 2013 10:49:07 -0400 Date: Wed, 26 Jun 2013 09:49:04 -0500 From: Nathan Zimmer To: Ingo Molnar Cc: Nathan Zimmer , holt@sgi.com, travis@sgi.com, rob@landley.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, yinghai@kernel.org, akpm@linux-foundation.org, gregkh@linuxfoundation.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Peter Zijlstra Subject: Re: [RFC 2/2] x86_64, mm: Reinsert the absent memory Message-ID: <20130626144903.GA2210@asylum.americas.sgi.com> References: <1371831934-156971-1-git-send-email-nzimmer@sgi.com> <1371831934-156971-3-git-send-email-nzimmer@sgi.com> <20130623092840.GB13445@gmail.com> <20130624203657.GA107621@asylum.americas.sgi.com> <20130626121430.GA4980@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130626121430.GA4980@gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1038 Lines: 31 On Wed, Jun 26, 2013 at 02:14:30PM +0200, Ingo Molnar wrote: > > * Nathan Zimmer wrote: > > > perf seems to struggle with 512 cpus, but I did get some data. > > Btw., mind outlining in what way it struggles? > > Thanks, > > Ingo System interactivity take a nose dive, including the ability to halt perf. The commands do get through but they take a while. Other processes tend to make signifigantly reduced progress. Also it tends to slow down all running processes. My guess it is the NMIs overwhelming the system but I have not found a good way to profile perf gone wild so it is only a guess. The issue mitigate somewhat by restrictring the number of cpus perf is recording or by not using the -g option, but sometimes I do need data on the whole system. Nate -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/