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 A9C96C5AD4C for ; Thu, 23 Nov 2023 16:09:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345086AbjKWQJC (ORCPT ); Thu, 23 Nov 2023 11:09:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229862AbjKWQJA (ORCPT ); Thu, 23 Nov 2023 11:09:00 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F901D48 for ; Thu, 23 Nov 2023 08:09:06 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A6FEC433C7; Thu, 23 Nov 2023 16:09:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700755746; bh=oAuo1J2PYet/KdK7D1flnc+jXpKcxa82RxxO55CgyuE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RPvHwSz2szhNlt2cVuK917ucGSXj1f5o+U7tSU9X+JNK7Hw9qKVw3KUAgiG3Ljrst tR2gjGVctto6ruzTlhS7HyaXh9Z8PPci+9kMbN6p9MiN9czCfl/vJjHqHlfAcF2S7W WOuzL14v1DEOoE1CtUk0oZJcEULe2I/hl2LjM68OfPpwYzL0WpUHXisDRno2SgdIA9 68bX1F+ehBJ3NC+7k25ld7+Hf6d46g01JN2YafS23t1FmVNo+EJk3sQzhMZhwWdUVN XmnqzOImQH1n2q7KHnQR+88E0IurIflU/gAPfo9fx8AKf5k0CGPmaY/LsfJGateurE e/9b8D82hP6uQ== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1r6CGF-00FpQF-TW; Thu, 23 Nov 2023 16:09:04 +0000 Date: Thu, 23 Nov 2023 16:09:02 +0000 Message-ID: <86bkbkzc2p.wl-maz@kernel.org> From: Marc Zyngier To: Ian Rogers Cc: Mark Rutland , Hector Martin , Arnaldo Carvalho de Melo , Namhyung Kim , Peter Zijlstra , Ingo Molnar , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v1] perf parse-events: Make legacy events lower priority than sysfs/json In-Reply-To: References: <20231123042922.834425-1-irogers@google.com> <86cyw0zeiu.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: irogers@google.com, mark.rutland@arm.com, marcan@marcan.st, acme@kernel.org, namhyung@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, adrian.hunter@intel.com, kan.liang@linux.intel.com, james.clark@arm.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 23 Nov 2023 15:27:54 +0000, Ian Rogers wrote: >=20 > On Thu, Nov 23, 2023 at 7:16=E2=80=AFAM Marc Zyngier wro= te: > > > > Again, perf gets shipped in distros, and not necessary as the latest > > version. Rather, they tend to ship the version matching the kernel. No > > backport, buggy perf. >=20 > Please complain to the distros. I complained to Debian, we got rid of > the horrible wrapper script thing they did. I complained to two > separate Ubuntu people over the last two weeks as they still have > broken packaging even though they derive from Debian. Fedora is of > course perfect as Arnaldo oversees it :-) In this instance, I don't need to complain to anyone but you. And guess what: it is on Fedora that this issue was first discovered. I also don't see what distro packaging policy has anything to do with the issue at hand, but that's beside the point. >=20 > > And again, I don't see a bug in the PMU driver. >=20 > Whether the PMU driver is requested a legacy cycles event or the > cycles event as an event code, the PMU driver should support it. > Supporting legacy events is just something core PMU drivers do. This > workaround wouldn't be necessary were it not for this PMU bug. Again, *which* PMU bug? What is a legacy event, and when has this terminology made it into the kernel? Who has decided that a change was necessary? Why haven't you submitted patches upgrading all the PMU drivers to support whatever you are referring to? > This change impacts every user of perf not just a partial fix to > workaround ARM PMU driver issues, see the updated parse-events test > for a list of what a simple test sees as a behavior change. When making far-reaching changes to a subsystem, I apply two rules: - I address everything that is affected, not just my pet architecture - I don't break other people's toys, which means compatibility is a *must*, not a 'nice to have' By this standard, your complaining that "ARM is broken" doesn't hold. It was working just fine until your changes rendered perf unusable. Nonetheless, thank you for addressing it quickly. This is sincerely appreciated. M. --=20 Without deviation from the norm, progress is not possible.