Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755017AbbDTMh7 (ORCPT ); Mon, 20 Apr 2015 08:37:59 -0400 Received: from mga01.intel.com ([192.55.52.88]:12504 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754730AbbDTMhz convert rfc822-to-8bit (ORCPT ); Mon, 20 Apr 2015 08:37:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,609,1422950400"; d="scan'208";a="697934876" From: "Brown, Len" To: Ingo Molnar , Len Brown CC: "x86@kernel.org" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner Subject: RE: [PATCH 1/1] x86: replace cpu_up hard-coded mdelay with variable Thread-Topic: [PATCH 1/1] x86: replace cpu_up hard-coded mdelay with variable Thread-Index: AQHQejtB5DqAWzVn+EOQ9DXUDafaeJ1V88cA///jbZA= Date: Mon, 20 Apr 2015 12:37:52 +0000 Message-ID: <1A7043D5F58CCB44A599DFD55ED4C94846861500@fmsmsx115.amr.corp.intel.com> References: <1429404795-23260-1-git-send-email-lenb@kernel.org> <87d69aab88c14d65ae1e7be55050d1b689b59b4b.1429402494.git.len.brown@intel.com> <20150420071306.GA14315@gmail.com> In-Reply-To: <20150420071306.GA14315@gmail.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.1.200.106] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 920 Lines: 25 > What's the cutoff for 'modern hardware' - which CPUs stopped requiring > the delay? This is the topic of ongoing research, and I'm not ready to send the patch setting a new default until I've heard back from a few more HW people. Every system I've tested appears to work with delay 0. Were I to guess, I'd venture that every system that runs an X86_64 kernel might count as "modern" -- even the 2005 AMD Turion laptop I've got in the bone pile. > Also, is there any public document where the no-delay is specified for > 'modern hardware'? Unfortunately only the converse is true. There is an ancient document specifying that the delay may be necessary. cheers, -Len -- 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/