From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA5C9C6FA90 for ; Thu, 22 Sep 2022 16:36:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231208AbiIVQgU (ORCPT ); Thu, 22 Sep 2022 12:36:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231220AbiIVQgP (ORCPT ); Thu, 22 Sep 2022 12:36:15 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 080279CCCA; Thu, 22 Sep 2022 09:36:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663864575; x=1695400575; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=XksDpOqRwt44B4iEf3mFYfxR+zBGMcBBxmzTBp9XKR8=; b=gD0ug7s4Nr28P++pQyKmHmiK6BGPEQDwBJVw5RI2FCIPofb3CRBOxj7I TlJFLaNy6BY7xEt7AOV0kjkj0k7Mbc6DPziMP8Ra8D0mAAeAjtUWyartm NTKaS/07/JvK/u0uXjLx2Y/UVG2s4UqI0N5qhm/sDMgwOnnlL+QzeQ9tb Gk2HZG7LSY222GRKSjvdIJONTd9hjM15uhGZOU49L3ayk/c+mYdVINKEK 6sdhYERfGQhSaSFABQKquMMnwMqw6msADpBzpvdO7Kt9zpD2Gs80e0s+j Crlv0r+YOQ2mn/ZcpjYlvtTyRbpqOC5BQwVRSzh/hCejBb9C3JCuzOvRA A==; X-IronPort-AV: E=McAfee;i="6500,9779,10478"; a="300338827" X-IronPort-AV: E=Sophos;i="5.93,335,1654585200"; d="scan'208";a="300338827" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Sep 2022 09:36:14 -0700 X-IronPort-AV: E=Sophos;i="5.93,335,1654585200"; d="scan'208";a="615275113" Received: from sponnura-mobl1.amr.corp.intel.com (HELO [10.209.58.200]) ([10.209.58.200]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Sep 2022 09:36:05 -0700 Message-ID: Date: Thu, 22 Sep 2022 09:36:05 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture Content-Language: en-US To: "Rafael J. Wysocki" , Borislav Petkov Cc: Peter Zijlstra , K Prateek Nayak , Linux Kernel Mailing List , Len Brown , ACPI Devel Maling List , Linux PM , Dave Hansen , Thomas Gleixner , andi@lisas.de, Pu Wen , Mario Limonciello , "Zhang, Rui" , "Guilherme G. Piccoli" , Daniel Lezcano , ananth.narayan@amd.com, gautham.shenoy@amd.com, Calvin Ong , Stable , regressions@lists.linux.dev References: <20220921063638.2489-1-kprateek.nayak@amd.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 9/22/22 08:53, Rafael J. Wysocki wrote: > On Thu, Sep 22, 2022 at 5:36 PM Borislav Petkov wrote: >> On Thu, Sep 22, 2022 at 05:21:21PM +0200, Rafael J. Wysocki wrote: >>> Well, it can be forced to use ACPI idle instead. >> Yeah, I did that earlier. The dummy IO read in question costs ~3K on >> average on my Coffeelake box here. > Well, that's the cost of forcing something non-default. Just to be clear: The _original_ AMD Zen problem that this thread is addressing is from a *default* configuration, right? It isn't that someone overrode the idle defaults?