From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932786AbcAKMPB (ORCPT ); Mon, 11 Jan 2016 07:15:01 -0500 Received: from foss.arm.com ([217.140.101.70]:54833 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932103AbcAKMO7 (ORCPT ); Mon, 11 Jan 2016 07:14:59 -0500 Subject: Re: [PATCH v5 08/11] arm-cci: Provide hook for writing to PMU counters To: Mark Rutland References: <1451908490-2615-1-git-send-email-suzuki.poulose@arm.com> <1451908490-2615-9-git-send-email-suzuki.poulose@arm.com> <20160111105454.GG6499@leverpostej> Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, arm@kernel.org, punit.agrawal@arm.com, peterz@infradead.org From: "Suzuki K. Poulose" Message-ID: <56939CC0.1@arm.com> Date: Mon, 11 Jan 2016 12:14:56 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20160111105454.GG6499@leverpostej> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/01/16 10:54, Mark Rutland wrote: > On Mon, Jan 04, 2016 at 11:54:47AM +0000, Suzuki K. Poulose wrote: >> static struct cci_pmu_model cci_pmu_models[]; >> @@ -846,7 +847,15 @@ static void pmu_write_counter(struct perf_event *event, u32 value) >> dev_err(&cci_pmu->plat_device->dev, "Invalid CCI PMU counter %d\n", idx); >> return; >> } >> - __pmu_write_counter(cci_pmu, value, idx); >> + >> + if (cci_pmu->model->write_counters) { >> + unsigned long mask[BITS_TO_LONGS(cci_pmu->num_cntrs)]; >> + >> + memset(mask, 0, BITS_TO_LONGS(cci_pmu->num_cntrs) * sizeof(unsigned long)); >> + set_bit(idx, mask); >> + cci_pmu->model->write_counters(cci_pmu, mask, value); >> + } else >> + __pmu_write_counter(cci_pmu, value, idx); >> } > > It would be much simpler to always log writes here, and only do the real > wirtes in batches when we re-enable the PMU (with appropriate > disable/enable calls in the IRQ handler). > > We'd still need special hooks for CCIs which require a special dance to > program them, but all the logic to handle the writes would be in one > place. This one is only there for the writes from the irq handler. Now that we have decided to disable pmu there, we could batch this one too. Cheers Suzuki