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 43BAFC433B4 for ; Tue, 4 May 2021 09:39:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A96C6115B for ; Tue, 4 May 2021 09:39:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230033AbhEDJks (ORCPT ); Tue, 4 May 2021 05:40:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229883AbhEDJkq (ORCPT ); Tue, 4 May 2021 05:40:46 -0400 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 792D4C061574; Tue, 4 May 2021 02:39:52 -0700 (PDT) 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=cbJaT3WauSqqefXiQhipxL5QKWvgRRw7UQHpsath+Uk=; b=Fh34MW0SJTuy07liXxCF50N1v5 UsnNeTvC+HKGbxyV5M1xr2rQelNWMXX9IWoY6Tbzyx0oYm7eXDki2pHgQEx4um74tCoQ7/J2c/3O2 IT0vqGHPLWuxKpHv5s4Ro9DMP2G1JaIjotX5SMqxYOvvUXIaboSoepUfRxlxPVTvS30lxOIAY9wWj 2VZnjiI7aDjJSf4xdI5yFB+pZC2YtdmyWdpUX/yrqvXNiJ2W4fhmnDPqQ432A5Q24tqH03jnfBBd/ GR1C3IcSA9c5RkJGXVfvXIzs14PCtbByXnfcDNOAVmRa6kzy6l75DJnJXHN5WsRK0IIMqmiK7n4+o jJrpY65g==; 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 (Red Hat Linux)) id 1ldrWl-00Ftkl-44; Tue, 04 May 2021 09:39:39 +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 017023001D0; Tue, 4 May 2021 11:39:37 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AAB992026F4BB; Tue, 4 May 2021 11:39:37 +0200 (CEST) Date: Tue, 4 May 2021 11:39:37 +0200 From: Peter Zijlstra To: Suravee Suthikulpanit Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, iommu@lists.linux-foundation.org, mingo@redhat.com, joro@8bytes.org, Jon.Grimm@amd.com, amonakov@ispras.ru, David Coe Subject: Re: [PATCH] x86/events/amd/iommu: Fix invalid Perf result due to IOMMU PMC power-gating Message-ID: References: <20210504065236.4415-1-suravee.suthikulpanit@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210504065236.4415-1-suravee.suthikulpanit@amd.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 04, 2021 at 01:52:36AM -0500, Suravee Suthikulpanit wrote: > 2. Since AMD IOMMU PMU does not support interrupt mode, the logic > can be simplified to always start counting with value zero, > and accumulate the counter value when stopping without the need > to keep track and reprogram the counter with the previously read > counter value. This relies on the hardware counter being the full 64bit wide, is it?