From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com [209.85.212.169]) by kanga.kvack.org (Postfix) with ESMTP id DBFBE6B0038 for ; Wed, 15 Apr 2015 10:48:33 -0400 (EDT) Received: by widdi4 with SMTP id di4so157833951wid.0 for ; Wed, 15 Apr 2015 07:48:33 -0700 (PDT) Received: from casper.infradead.org (casper.infradead.org. [2001:770:15f::2]) by mx.google.com with ESMTPS id do5si6104917wib.50.2015.04.15.07.48.30 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 15 Apr 2015 07:48:30 -0700 (PDT) Date: Wed, 15 Apr 2015 16:48:18 +0200 From: Peter Zijlstra Subject: Re: [RFC PATCH 0/14] Parallel memory initialisation Message-ID: <20150415144818.GX5029@twins.programming.kicks-ass.net> References: <1428920226-18147-1-git-send-email-mgorman@suse.de> <552E6486.6070705@hp.com> <20150415142731.GI17717@twins.programming.kicks-ass.net> <20150415143420.GG14842@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150415143420.GG14842@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Waiman Long , Linux-MM , Nathan Zimmer , Daniel Rahn , Davidlohr Bueso , Dave Hansen , Tom Vaden , Scott Norton , LKML On Wed, Apr 15, 2015 at 03:34:20PM +0100, Mel Gorman wrote: > On Wed, Apr 15, 2015 at 04:27:31PM +0200, Peter Zijlstra wrote: > > On Wed, Apr 15, 2015 at 09:15:50AM -0400, Waiman Long wrote: > > > I had included your patch with the 4.0 kernel and booted up a 16-socket > > > 12-TB machine. I measured the elapsed time from the elilo prompt to the > > > availability of ssh login. Without the patch, the bootup time was 404s. It > > > was reduced to 298s with the patch. So there was about 100s reduction in > > > bootup time (1/4 of the total). > > > > But you cheat! :-) > > > > How long between power on and the elilo prompt? Do the 100 seconds > > matter on that time scale? > > Calling it cheating is a *bit* harsh as the POST times vary considerably > between manufacturers. While I'm interested in Waiman's answer, I'm told > that those that really care about minimising reboot times will use kexec > to avoid POST. The 100 seconds is 100 seconds, whether that is 25% in > all cases is a different matter. Sure POST times vary, but its consistently stupid long :-) I'm forever thinking my EX machine died because its not coming back from a power cycle, and mine isn't really _that_ large. -- 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