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 93B3EC433F5 for ; Tue, 15 Feb 2022 15:47:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240555AbiBOPrn (ORCPT ); Tue, 15 Feb 2022 10:47:43 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:32842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240966AbiBOPpc (ORCPT ); Tue, 15 Feb 2022 10:45:32 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DAE8123BD2 for ; Tue, 15 Feb 2022 07:41:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644939662; x=1676475662; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=QV2lpkZ1uoeX6MQ6u1abca3syu0nEO8PCNGkVo6xNn8=; b=IVxYpOEkOnnQv3WyV+EjQIZFCnmjOR9St01j6y03v3nAk9Je/lbTrQ5g bkPLMGt7XyKErTk4U+/DoVgfV8qpbZTB/Kc+Lm6Lx9BVbKOVghY3fpkbR 7kg/78MbDJVLcevJNimKy+UVNcCIylbemckhh1gldsQX61rsy8xpdMJIe fMnS113aMZJlP+gJWwnNyuU6kcFH3lZP23P8dh/0HQmZxTpL0QAFPmMQf cF0/3R9W4Pt30R2y4zjhacFQBuW3JEgSO5WyBn/fnMoxp4GHJnerYhCch HYF3Nlj3GiQQnNZbFWzZz8zAbXHRc+/K/Z5LcYRfKq7wiT96zan77AnoG A==; X-IronPort-AV: E=McAfee;i="6200,9189,10258"; a="250320820" X-IronPort-AV: E=Sophos;i="5.88,371,1635231600"; d="scan'208";a="250320820" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Feb 2022 07:40:49 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,371,1635231600"; d="scan'208";a="539378825" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.92]) ([10.237.72.92]) by fmsmga007.fm.intel.com with ESMTP; 15 Feb 2022 07:40:46 -0800 Message-ID: Date: Tue, 15 Feb 2022 17:40:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.5.0 Subject: Re: [PATCH V2 0/2] perf/x86/intel/pt: Add support for event tracing and TNT disabling Content-Language: en-US To: Peter Zijlstra Cc: Alexander Shishkin , Andi Kleen , Arnaldo Carvalho de Melo , Jiri Olsa , linux-kernel@vger.kernel.org, Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, H Peter Anvin References: <20220126104815.2807416-1-adrian.hunter@intel.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/02/2022 17:35, Peter Zijlstra wrote: > On Wed, Jan 26, 2022 at 12:48:13PM +0200, Adrian Hunter wrote: >> Hi >> >> As of Intel SDM (https://www.intel.com/sdm) version 076, there are 2 new >> Intel PT features called Event Trace and TNT-Disable. >> >> Event Trace exposes details about asynchronous events such as interrupts >> and VM-Entry/Exit. >> >> TNT-Disable disables TNT packets to reduce the tracing overhead, but with >> the result that exact control flow information is lost. > > What's a TNT? The TNT packet indicates whether conditional branches were taken or not taken.