Date: Wed, 15 Apr 2015 16:48:18 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Waiman Long <waiman.long@hp.com>, Linux-MM <linux-mm@kvack.org>,
        Nathan Zimmer <nzimmer@sgi.com>, Daniel Rahn <drahn@suse.com>,
        Davidlohr Bueso <dbueso@suse.com>, Dave Hansen <dave.hansen@intel.com>,
        Tom Vaden <tom.vaden@hp.com>, Scott Norton <scott.norton@hp.com>,
        LKML <linux-kernel@vger.kernel.org>
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>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1445
Lines: 28

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 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/