Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752050Ab3FYHi1 (ORCPT ); Tue, 25 Jun 2013 03:38:27 -0400 Received: from mail-ee0-f49.google.com ([74.125.83.49]:51953 "EHLO mail-ee0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751092Ab3FYHiX (ORCPT ); Tue, 25 Jun 2013 03:38:23 -0400 Date: Tue, 25 Jun 2013 09:38:19 +0200 From: Ingo Molnar To: Nathan Zimmer Cc: 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: <20130625073819.GC11420@gmail.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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130624203657.GA107621@asylum.americas.sgi.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1209 Lines: 32 * Nathan Zimmer wrote: > On Sun, Jun 23, 2013 at 11:28:40AM +0200, Ingo Molnar wrote: > > > > That's 4.5 GB/sec initialization speed - that feels a bit slow and the > > boot time effect should be felt on smaller 'a couple of gigabytes' > > desktop boxes as well. Do we know exactly where the 2 hours of boot > > time on a 32 TB system is spent? > > There are other several spots that could be improved on a large system > but memory initialization is by far the biggest. My feeling is that deferred/on-demand initialization triggered from the buddy allocator is the better long term solution. That will also make it much easier to profile/test memory init performance: boot up a large system and run a simple testprogram that allocates a lot of RAM. ( It will also make people want to optimize the initialization sequence better, as it will be part of any freshly booted system's memory allocation overhead. ) Thanks, Ingo -- 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/