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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BDF3C43460 for ; Fri, 16 Apr 2021 13:41:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0FF1610FA for ; Fri, 16 Apr 2021 13:41:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243006AbhDPNlm (ORCPT ); Fri, 16 Apr 2021 09:41:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233606AbhDPNll (ORCPT ); Fri, 16 Apr 2021 09:41:41 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17FA8C061574 for ; Fri, 16 Apr 2021 06:41:17 -0700 (PDT) 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=R6QwyoIHLujEky6poAogx4uw5mzz6A2pMKg7WGcrQRo=; b=uqCVr2k6T9SY+UIUGXhafWZQey mJJXfZ4s5qyQMYJquAoUcAT2kpHmyiFXQRLBymEgc5RynJcG5N43vUs2HXG/jqQoL+sOWoV1QqNsF yU6wjugP5+r5DUAH/LbjZkC4ULfszxxhrwCkvVCrIsYm0DKUL/01W4qATs2m98I4xwn/wZzMyaQx7 NW6pNKHTIyQ9AJFgsjxnvDAuSmntqO9ohOYXikaJmaAcnUXKuem+opA68j6kj5Y3oFbQgABX9Tyrd s3pWn+L9TyttXkJzwyTV4oc4Cwh8OtRi2pFsrGzhojwAFZQS8ZZcH4opog2VEmOENkg8is7WV3dFj TpjFnVuA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lXOh8-00A0RE-HL; Fri, 16 Apr 2021 13:39:55 +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 (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 87A32300212; Fri, 16 Apr 2021 15:39:35 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 53D962BE84B4D; Fri, 16 Apr 2021 15:39:35 +0200 (CEST) Date: Fri, 16 Apr 2021 15:39:35 +0200 From: Peter Zijlstra To: Namhyung Kim Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Jiri Olsa , Mark Rutland , Alexander Shishkin , LKML , Stephane Eranian , Andi Kleen , Ian Rogers , Song Liu , Tejun Heo , kernel test robot , Thomas Gleixner Subject: Re: [PATCH v3 1/2] perf/core: Share an event with multiple cgroups Message-ID: References: <20210413155337.644993-1-namhyung@kernel.org> <20210413155337.644993-2-namhyung@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 16, 2021 at 09:19:08PM +0900, Namhyung Kim wrote: > > Are you actually using mmap() to read? I had a proposal for FORMAT_GROUP > > like thing for mmap(), but I never implemented that (didn't get the > > enthousiatic response I thought it would). But yeah, there's nowhere > > near enough space in there for PERCPU. > > Recently there's a patch to do it with rdpmc which needs to mmap first. > > https://lore.kernel.org/lkml/20210414155412.3697605-1-robh@kernel.org/ Yeah, I'm not sure about that, I've not looked at it recently. The thing is though; for RDPMC to work, you *NEED* to be on the same CPU as the counter. The typical RDPMC use-case is self monitoring.