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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham 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 3777EC43144 for ; Fri, 29 Jun 2018 13:27:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA7E127F48 for ; Fri, 29 Jun 2018 13:27:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA7E127F48 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754930AbeF2N1d (ORCPT ); Fri, 29 Jun 2018 09:27:33 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:34224 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753287AbeF2N1c (ORCPT ); Fri, 29 Jun 2018 09:27:32 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 71B0E80D; Fri, 29 Jun 2018 06:27:31 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3DB893F318; Fri, 29 Jun 2018 06:27:30 -0700 (PDT) Date: Fri, 29 Jun 2018 14:27:25 +0100 From: Mark Rutland To: Suzuki K Poulose Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will.deacon@arm.com, robin.murphy@arm.com, julien.thierry@arm.com Subject: Re: [PATCH v3 4/7] arm_pmu: Tidy up clear_event_idx call backs Message-ID: <20180629132724.ztcfelcnb2dt2u35@lakrids.cambridge.arm.com> References: <1529403342-17899-1-git-send-email-suzuki.poulose@arm.com> <1529403342-17899-5-git-send-email-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1529403342-17899-5-git-send-email-suzuki.poulose@arm.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 19, 2018 at 11:15:39AM +0100, Suzuki K Poulose wrote: > The armpmu uses get_event_idx callback to allocate an event > counter for a given event, which marks the selected counter > as "used". Now, when we delete the counter, the arm_pmu goes > ahead and clears the "used" bit and then invokes the "clear_event_idx" > call back, which kind of splits the job between the core code > and the backend. Tidy this up by relying on the clear_event_idx > to do the book keeping, if available. Otherwise, let the core > driver do the default "clear" bit operation. This will be useful > for adding the chained event support, where we leave the event > idx maintenance to the backend. > > Also, when an event is removed from the PMU, reset the hw.idx > to indicate that a counter is not allocated for this event, > to help the backends do better checks. This will be also used > for the chain counter support. > > Cc: Mark Rutland > Cc: Will Deacon > Reviewed-by: Julien Thierry > Signed-off-by: Suzuki K Poulose TBH, I think it might be better to make clear_event_idx() mandatory, such that each backend provides both clear / set, next to each other in the code. It's a bit more code, but it would restore orthogonality to the API. Mark. > --- > Changes since v2: > - Reset the event counter after an event is removed. > --- > arch/arm/kernel/perf_event_v7.c | 2 ++ > drivers/perf/arm_pmu.c | 17 +++++++++++++---- > 2 files changed, 15 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c > index fd7ce01..765d265 100644 > --- a/arch/arm/kernel/perf_event_v7.c > +++ b/arch/arm/kernel/perf_event_v7.c > @@ -1637,6 +1637,7 @@ static void krait_pmu_clear_event_idx(struct pmu_hw_events *cpuc, > bool venum_event = EVENT_VENUM(hwc->config_base); > bool krait_event = EVENT_CPU(hwc->config_base); > > + clear_bit(hwc->idx, cpuc->used_mask); > if (venum_event || krait_event) { > bit = krait_event_to_bit(event, region, group); > clear_bit(bit, cpuc->used_mask); > @@ -1966,6 +1967,7 @@ static void scorpion_pmu_clear_event_idx(struct pmu_hw_events *cpuc, > bool venum_event = EVENT_VENUM(hwc->config_base); > bool scorpion_event = EVENT_CPU(hwc->config_base); > > + clear_bit(hwc->idx, cpuc->used_mask); > if (venum_event || scorpion_event) { > bit = scorpion_event_to_bit(event, region, group); > clear_bit(bit, cpuc->used_mask); > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index e3766a8..6e10e8c 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -227,6 +227,16 @@ static void armpmu_start(struct perf_event *event, int flags) > armpmu->enable(event); > } > > +static void armpmu_clear_event_idx(struct arm_pmu *armpmu, > + struct pmu_hw_events *hw_events, > + struct perf_event *event) > +{ > + if (armpmu->clear_event_idx) > + armpmu->clear_event_idx(hw_events, event); > + else > + clear_bit(event->hw.idx, hw_events->used_mask); > +} > + > static void > armpmu_del(struct perf_event *event, int flags) > { > @@ -237,11 +247,10 @@ armpmu_del(struct perf_event *event, int flags) > > armpmu_stop(event, PERF_EF_UPDATE); > hw_events->events[idx] = NULL; > - clear_bit(idx, hw_events->used_mask); > - if (armpmu->clear_event_idx) > - armpmu->clear_event_idx(hw_events, event); > - > + armpmu_clear_event_idx(armpmu, hw_events, event); > perf_event_update_userpage(event); > + /* Clear the allocated counter */ > + hwc->idx = -1; > } > > static int > -- > 2.7.4 >