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 007E4C05027 for ; Mon, 23 Jan 2023 20:41:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232111AbjAWUlT (ORCPT ); Mon, 23 Jan 2023 15:41:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232728AbjAWUlK (ORCPT ); Mon, 23 Jan 2023 15:41:10 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12F2A3800B for ; Mon, 23 Jan 2023 12:40:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0xN7hOPDsbgth1lPxi0MXO8fcKBUctMvHiKYNT0njNY=; b=iH2KtTEZUm2GCo5Ai3vYCcozMK TyX8083e9g6tvTsF6AeH0yOASL2bZ0JdZWU64xjpxSEKQ4LzJA71SzJJK03Xvrccyz3sVNIIwzi6G 7kG5IxLqnM+cZqlr+aM66s/TkoEt51mnrkLwhqP8bDvnhU5zau0raV1WnX9TnIY4nA+RwRHIbJx5J YPNcD/6LNhapgrxLz+Li6D/U6TG2D9ZtSjVf+Rm2hYt1HC0pWZytRs+tLtmW47P9L+465YyC0TjZ2 XIRL8IPJ7uK5ksS7FPnfs59Tf9Q3ya+cg32tG7G8O2XESIjA0t+uwonxGoA8DNRObprDN6cZ5xjW1 moP52f1Q==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pK3aj-001dch-0f; Mon, 23 Jan 2023 20:38:57 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 402963001E7; Mon, 23 Jan 2023 21:39:25 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 227F22077B1DE; Mon, 23 Jan 2023 21:39:25 +0100 (CET) Date: Mon, 23 Jan 2023 21:39:25 +0100 From: Peter Zijlstra To: kan.liang@linux.intel.com Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, namhyung@kernel.org, eranian@google.com, ak@linux.intel.com, Thomas Gleixner Subject: Re: [PATCH] perf/x86/intel/ds: Fix the conversion from TSC to perf time Message-ID: References: <20230123172027.125385-1-kan.liang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230123172027.125385-1-kan.liang@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 23, 2023 at 09:20:27AM -0800, kan.liang@linux.intel.com wrote: > The TSC unstable case seems to be some corner cases (e.g., due to broken > BIOS). This patch doesn't support the conversion when the TSC is > unstable. The TSC in a PEBS record will be dropped and fallback to the > software perf time provided by the generic code. :-( You're saying there's modern systems (PEBS timestamps are fairly new) that trigger unstable TSC ? What systems in specific have you observed this on -- we really need to name and shame them, this is fully unacceptable.