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 856BCC433F5 for ; Wed, 9 Feb 2022 12:55:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233733AbiBIMyz (ORCPT ); Wed, 9 Feb 2022 07:54:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229922AbiBIMyp (ORCPT ); Wed, 9 Feb 2022 07:54:45 -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 5AB60C0613CA; Wed, 9 Feb 2022 04:54:49 -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=7b9c8GzE9tZkc6eT+rdeNdrr/Q/IwhVZG6xv7vX09Oo=; b=AlUVTn5XlgNzFiPIF6CHIb2Xpb P2arMilZX7owI9BZYCtG1B4txJV2NTH/pQP/HmmGismw16bbx+EYnYYxZ+nV2Jfy5aD9uEY3/NSBx t3CQRDcAv6uuxb5HM/ws8TH9Uo4TsL0ayS15WJqj6JGmQUEqOOXkyPe1LHD4JCioJXA1BB2/M3KQ2 3Rd4gHAsFj0e8P5PLhMwcvBNTyupgNKrvgT7ikqv4t2ElypFe1rtCl/dfO+5mcoflS8bff+5YBMrg zye1qdhoAzTZlLDY+1d5fpbzHAjXqaCogzHRBMpEIzbBTMsyU7VoObyrw+REPjF+KNz3D5Gg0PXhB xtneKLkg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nHmUK-008QQo-NT; Wed, 09 Feb 2022 12:54:25 +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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0E749300478; Wed, 9 Feb 2022 13:54:24 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EBCDE265018D6; Wed, 9 Feb 2022 13:54:23 +0100 (CET) Date: Wed, 9 Feb 2022 13:54:23 +0100 From: Peter Zijlstra To: Adrian Hunter Cc: Alexander Shishkin , Arnaldo Carvalho de Melo , Jiri Olsa , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, kvm@vger.kernel.org, H Peter Anvin , Mathieu Poirier , Suzuki K Poulose , Leo Yan Subject: Re: [PATCH 01/11] perf/x86: Fix native_perf_sched_clock_from_tsc() with __sched_clock_offset Message-ID: References: <20220209084929.54331-1-adrian.hunter@intel.com> <20220209084929.54331-2-adrian.hunter@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220209084929.54331-2-adrian.hunter@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 09, 2022 at 10:49:19AM +0200, Adrian Hunter wrote: > native_perf_sched_clock_from_tsc() is used to produce a time value that can > be consistent with perf_clock(). Consequently, it should be adjusted by > __sched_clock_offset, the same as perf_clock() would be. > > Fixes: 698eff6355f735 ("sched/clock, x86/perf: Fix perf test tsc") > Signed-off-by: Adrian Hunter > --- > arch/x86/kernel/tsc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > index a698196377be..c1c73fe324cd 100644 > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -242,7 +242,8 @@ u64 native_sched_clock(void) > */ > u64 native_sched_clock_from_tsc(u64 tsc) > { > - return cycles_2_ns(tsc); > + return cycles_2_ns(tsc) + > + (sched_clock_stable() ? __sched_clock_offset : 0); > } Why do we care about the !sched_clock_stable() case?