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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83251ECE560 for ; Sun, 23 Sep 2018 21:54:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E5DA20989 for ; Sun, 23 Sep 2018 21:54:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=comcast.net header.i=@comcast.net header.b="lzH6WLl3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1E5DA20989 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=comcast.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727280AbeIXDx1 (ORCPT ); Sun, 23 Sep 2018 23:53:27 -0400 Received: from resqmta-ch2-03v.sys.comcast.net ([69.252.207.35]:33322 "EHLO resqmta-ch2-03v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726520AbeIXDx1 (ORCPT ); Sun, 23 Sep 2018 23:53:27 -0400 Received: from resomta-ch2-12v.sys.comcast.net ([69.252.207.108]) by resqmta-ch2-03v.sys.comcast.net with ESMTP id 4CHUgdJUBPUIw4CKdgeazY; Sun, 23 Sep 2018 21:54:23 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1537739663; bh=ozBS/3YtQT+ZEMp6NCYGolIle4BnTZ3kBc+HJ8/2gug=; h=Received:Received:Subject:To:From:Message-ID:Date:MIME-Version: Content-Type; b=lzH6WLl31/7ThxyEmBN7Dl6HO6UQ4d71SYRcCC8Cia56qQwpQfy7qo2BT80wVSDK4 /ztWMvQUWHD1DQb2XjXv+MSRFCKsj5gzGaH3siwEgYi0gSrEfmEWeLhXHzPqF7zPAA FISvhUGSgWnGasSPr3fFkFyegLcq5pX4PiFn3yk21yCXtK7ueOYVdRA1Z+4pK91U/q GY6Ca1AlpOCKhxiPuQkFpnpC4XQZXN76Zc0pzMV0LcHYU2UWLOwZJu/5uf6qNd/rdV tEM+Pmcq2Y9iWb2YAEHVGrZ9qfvfrAnggl4zFHjJouX+SJcYdTUE4vCBOHTKbgEmF7 A5wVM43VANtRw== Received: from [10.1.10.100] ([73.214.254.59]) by resomta-ch2-12v.sys.comcast.net with ESMTPSA id 4CKcgRnarT2X34CKdg2faP; Sun, 23 Sep 2018 21:54:23 +0000 Subject: Re: AMD Athlon bogus performance value causing RCU stalls? To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org References: <6243f7cc-1a80-db0b-4765-fa12bda9b06a@comcast.net> From: Rob Prowel Message-ID: Date: Sun, 23 Sep 2018 17:54:22 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfKtHwqGCZ1miu1CggW6UdpVF+aXHvL8GoboKMA3pDEPUaz0mC2dq6lAr+DDX0sAzgRW2pXiJ7oS7mfVKew1+o8g2I9goIBRgmM0Otv38M9DwABKUs/Ph NJqyp+BigYI6aqYZkqtU+gKjteTSLxNdzRbRCQtRm9YVMk00ZuDSZNak0wRJhGlN5UeiyuVnMEIUENv9AihkyManhCMTg1BxPiI= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/23/18 17:19, Thomas Gleixner wrote: >> >> What is that value for the second Athlon core (seems extremely bogus), and >> would/could that be the reason for the schedule_timeouts? This bogus value >> also shows up in the bootup log when the second core is activated. Seems to >> be AMD specific, as the values are correct on my Xeon machines. > > That's a 32bit machine I assume. No. Actually it is a 64 bit AMD Athlon. Might need to check the math being a problem in the 64 bit domain as well. > > Yes. This was decoded recently as an issue on 32bit due to a calculation > which is based on 'unsigned long' but requires to be 64bit wide. > > It's in the 4.18.8 stable kernel, which should be available from your > fedora repo anytime soon. > Will check with the newer kernel when it's available but please do double check if this problem might exist on 64 bit architectures as well...and of course I'm interested to know whether it is the likely cuprit of my RCU problem.