Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030292AbbD1QGI (ORCPT ); Tue, 28 Apr 2015 12:06:08 -0400 Received: from mail-wg0-f54.google.com ([74.125.82.54]:35622 "EHLO mail-wg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965701AbbD1QGG (ORCPT ); Tue, 28 Apr 2015 12:06:06 -0400 MIME-Version: 1.0 In-Reply-To: <1430231830-7702-1-git-send-email-mgorman@suse.de> References: <1430231830-7702-1-git-send-email-mgorman@suse.de> Date: Tue, 28 Apr 2015 19:06:04 +0300 X-Google-Sender-Auth: _ytK4n9j6-hI0Xg_uWJ3w3U8CdI Message-ID: Subject: Re: [PATCH 0/13] Parallel struct page initialisation v4 From: Pekka Enberg To: Mel Gorman Cc: Andrew Morton , Nathan Zimmer , Dave Hansen , Waiman Long , Scott Norton , Daniel J Blueman , Linux-MM , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1784 Lines: 41 On Tue, Apr 28, 2015 at 5:36 PM, Mel Gorman wrote: > Struct page initialisation had been identified as one of the reasons why > large machines take a long time to boot. Patches were posted a long time ago > to defer initialisation until they were first used. This was rejected on > the grounds it should not be necessary to hurt the fast paths. This series > reuses much of the work from that time but defers the initialisation of > memory to kswapd so that one thread per node initialises memory local to > that node. > > After applying the series and setting the appropriate Kconfig variable I > see this in the boot log on a 64G machine > > [ 7.383764] kswapd 0 initialised deferred memory in 188ms > [ 7.404253] kswapd 1 initialised deferred memory in 208ms > [ 7.411044] kswapd 3 initialised deferred memory in 216ms > [ 7.411551] kswapd 2 initialised deferred memory in 216ms > > On a 1TB machine, I see > > [ 8.406511] kswapd 3 initialised deferred memory in 1116ms > [ 8.428518] kswapd 1 initialised deferred memory in 1140ms > [ 8.435977] kswapd 0 initialised deferred memory in 1148ms > [ 8.437416] kswapd 2 initialised deferred memory in 1148ms > > Once booted the machine appears to work as normal. Boot times were measured > from the time shutdown was called until ssh was available again. In the > 64G case, the boot time savings are negligible. On the 1TB machine, the > savings were 16 seconds. FWIW, Acked-by: Pekka Enberg for the whole series. - Pekka -- 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/