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 3E7D5C05027 for ; Tue, 14 Feb 2023 20:55:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231935AbjBNUz6 (ORCPT ); Tue, 14 Feb 2023 15:55:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230107AbjBNUz4 (ORCPT ); Tue, 14 Feb 2023 15:55:56 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 763B2298CC for ; Tue, 14 Feb 2023 12:55:55 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1676408154; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DUOIZuJdLZ75nj03a3zeKvglfxGqzebdblZ7SweGKPY=; b=FCNHyRxr41HuCa/UjE2mA1iF7ZoMHxJYx00ntnQlL2shoAr6pidRP5/bB1WsI40dh64NVF CQ2ZIa183BNcW72WhedH/SumgCQdruBgQk6JW/C7Z1cgJHAhDUbGIHwer9PeKeoFvCGQu2 BQrzbgmNnM33lPHf0AzetAbO6AnfT+DHUwMYWVgWgYFodShM7Jg6QKFPzY7SoLvX8lXjk2 vx2OpSxrNpxSoAElgNlG7F1rjRyU1rsPLxZt4/QszfEHIo0l8OvLWqhK6uu0jpZv0RYmZB Xpy2QrJp0SDZf3jlO0Q5Ykvv9yybNOXpCV+ibxwDdGFY087esuV4tWFPOf5+2A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1676408154; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DUOIZuJdLZ75nj03a3zeKvglfxGqzebdblZ7SweGKPY=; b=iTtLTSUryfnTWb17wWZcxtclMcVfEAod4aGFDhvwA3ycITeDM3JKh/YzK/zdjmdHoSjfxG zrCHjCpY0FJL5IDw== To: "Liang, Kan" , jstultz@google.com, peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org Cc: sboyd@kernel.org, eranian@google.com, namhyung@kernel.org, ak@linux.intel.com, adrian.hunter@intel.com, Ravi Bangoria Subject: Re: [RFC PATCH V2 4/9] perf/x86: Enable post-processing monotonic raw conversion In-Reply-To: <4372ae84-76e2-8bae-b0ad-87102973df67@linux.intel.com> References: <20230213190754.1836051-1-kan.liang@linux.intel.com> <20230213190754.1836051-5-kan.liang@linux.intel.com> <875yc4rp68.ffs@tglx> <4372ae84-76e2-8bae-b0ad-87102973df67@linux.intel.com> Date: Tue, 14 Feb 2023 21:55:53 +0100 Message-ID: <873578rmp2.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 14 2023 at 15:21, Kan Liang wrote: > On 2023-02-14 3:02 p.m., Thomas Gleixner wrote: >> >> What guarantees that the clocksource used by the timekeeping core is >> actually TSC? Nothing at all. You cannot make assumptions here. >> > > Yes, you are right. > I will add a check to make sure the clocksource is TSC when perf does > the conversion. > > Could you please comment on whether the patch is in the right direction? > This V2 patch series expose the kernel internal conversion information > into the user space. Is it OK for you? Making the conversion info an ABI is suboptimal at best. I'm still trying to wrap my brain around all of this. Will reply over there once my confusion subsides. Thanks, tglx