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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5749ECA0FE7 for ; Tue, 26 Aug 2025 13:09:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WLdSSfqhu0LV/K1YAgsjsa3xTiVERY4Lw13byKLJI9E=; b=nHgl9EKOwBv7Ms 9w/ebizRrU0p0cP/C78dZVdivPpxggWQV53HtngygZ11KHcr7c623Hq/oLpWGBM6xmGtCBjNJRBaV QxwbqCpojA5Vp+iSHBe/f55q5OjrK0EFxYAB8VBs18fdcBuC+fogn5hD7m+CVW1un6Uh8IlKjhjMA pP+nb+7wTqZbsW18svsqMv3Oy8bE5PLtMs0zDiyYF6+AnKKCcu3Dpcdv/fN8Xcwq8WPFwfr6IEb8r YABS/mQNqbKX/g/HtQBpNH9GECvfXmMBY2K1Ix0qMQ6HLqyrH1Kc57bJ2f/nqZkOCn9x37TpSN1VA ZLaG4VzOeMXhJOJHb2BA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqtQ7-0000000C2qn-3OTg; Tue, 26 Aug 2025 13:09:03 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqtKn-0000000C1mf-3py9; Tue, 26 Aug 2025 13:03:33 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=pe5SE8cLTPPyLKyF6S5l44TjxJSycuwoPwH53Hc4MBc=; b=s5T3h8QunORHMVi1lJq+TueBjc cEFljtvjN5QJ03jRIuUbqZT2dzYWLCkq7EIgZ1HjiZepKSvKZUS4jhIftbJpUomzAxLkXpo4MhYIl ZCvpLQBdWeqllwk2L5LEakNCj50aVxzY1I5n8BnO+qCbmyfysUZaBrevf4ZwX/NHQuj2PrtwGK3Is jhSt6FlQLnGrrRwVWOG3VEhB1mGDJu+1EhbkwSGhAG25rhQM5DyWklhsvsXQh2tW5FYLoYbc8dttl tsa9sX+EEmcEbn/jBCdJY0wOlh7GZntWiVjKPlxT8hw9CmspDWHiAZfhSZSTIR8f/mKGoVnI/OKYV DfymEZ2w==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqtKk-00000002CWx-1CxP; Tue, 26 Aug 2025 13:03:31 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id E7FAC3002C5; Tue, 26 Aug 2025 15:03:29 +0200 (CEST) Date: Tue, 26 Aug 2025 15:03:29 +0200 From: Peter Zijlstra To: Robin Murphy Cc: mingo@redhat.com, will@kernel.org, mark.rutland@arm.com, acme@kernel.org, namhyung@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, linux-csky@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-pm@vger.kernel.org, linux-rockchip@lists.infradead.org, dmaengine@vger.kernel.org, linux-fpga@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, coresight@lists.linaro.org, iommu@lists.linux.dev, linux-amlogic@lists.infradead.org, linux-cxl@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH 12/19] perf: Ignore event state for group validation Message-ID: <20250826130329.GX4067720@noisy.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org On Wed, Aug 13, 2025 at 06:01:04PM +0100, Robin Murphy wrote: > It may have been different long ago, but today it seems wrong for these > drivers to skip counting disabled sibling events in group validation, > given that perf_event_enable() could make them schedulable again, and > thus increase the effective size of the group later. Conversely, if a > sibling event is truly dead then it stands to reason that the whole > group is dead, so it's not worth going to any special effort to try to > squeeze in a new event that's never going to run anyway. Thus, we can > simply remove all these checks. So currently you can do sort of a manual event rotation inside an over-sized group and have it work. I'm not sure if anybody actually does this, but its possible. Eg. on a PMU that supports only 4 counters, create a group of 5 and periodically cycle which of the 5 events is off. So I'm not against changing this, but changing stuff like this always makes me a little fearful -- it wouldn't be the first time that when it finally trickles down to some 'enterprise' user in 5 years someone comes and finally says, oh hey, you broke my shit :-( _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip