Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752660AbbENHSp (ORCPT ); Thu, 14 May 2015 03:18:45 -0400 Received: from mail-la0-f50.google.com ([209.85.215.50]:36589 "EHLO mail-la0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750775AbbENHSo (ORCPT ); Thu, 14 May 2015 03:18:44 -0400 MIME-Version: 1.0 In-Reply-To: References: <1430732554-7294-1-git-send-email-jschoenh@amazon.de> <20150506082759.GA30019@gmail.com> <20150507102351.GA14347@gmail.com> Date: Thu, 14 May 2015 03:18:42 -0400 X-Google-Sender-Auth: G2ruF-yi1QS3LqERhDDKTP68g0s Message-ID: Subject: Re: [PATCH] x86: skip delays during SMP initialization similar to Xen From: Len Brown To: Ingo Molnar Cc: =?UTF-8?Q?Jan_H=2E_Sch=C3=B6nherr?= , Thomas Gleixner , X86 ML , "linux-kernel@vger.kernel.org" , Anthony Liguori , Ingo Molnar , "H. Peter Anvin" , Tim Deegan , Gang Wei , Linus Torvalds 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: 941 Lines: 27 On Thu, May 14, 2015 at 2:36 AM, Len Brown wrote: >> [ 2.737884] x86: Booted up 4 nodes, 120 CPUs > For the record, the same (bare metal) box running latest tip boots > 10ms/processor quicker > [ 1.553658] x86: Booted up 4 nodes, 120 CPUs > BTW. this time can be reduced by 7% (113 ms) by deleting announce_cpu(): > > [ 1.445815] x86: Booted up 4 nodes, 120 CPUs I see that the x2apic optimization has been reverted from TIP. So just for grins, I booted the same box with all the udelays in smpboot.c removed, and it speed up boot by only 12ms (0.8%) total: [ 1.432946] x86: Booted up 4 nodes, 120 CPUs cheers, -Len Brown, Intel Open Source Technology Center -- 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/