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=-15.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 C5EECC4338F for ; Fri, 30 Jul 2021 05:54:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A938461008 for ; Fri, 30 Jul 2021 05:54:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236603AbhG3FyE (ORCPT ); Fri, 30 Jul 2021 01:54:04 -0400 Received: from foss.arm.com ([217.140.110.172]:37308 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229948AbhG3FyD (ORCPT ); Fri, 30 Jul 2021 01:54:03 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 96D0D31B; Thu, 29 Jul 2021 22:53:58 -0700 (PDT) Received: from [10.163.66.9] (unknown [10.163.66.9]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D7333F66F; Thu, 29 Jul 2021 22:53:55 -0700 (PDT) Subject: Re: [PATCH v2 09/10] coresight: trbe: End the AUX handle on truncation To: Suzuki K Poulose , coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tamas.zsoldos@arm.com, al.grant@arm.com, leo.yan@linaro.org, mike.leach@linaro.org, mathieu.poirier@linaro.org, jinlmao@qti.qualcomm.com, Peter Zijlstra , Will Deacon References: <20210723124611.3828908-1-suzuki.poulose@arm.com> <20210723124611.3828908-10-suzuki.poulose@arm.com> From: Anshuman Khandual Message-ID: Date: Fri, 30 Jul 2021 11:24:44 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210723124611.3828908-10-suzuki.poulose@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/23/21 6:16 PM, Suzuki K Poulose wrote: > When we detect that there isn't enough space left to start > a meaningful session, we disable the TRBE, marking the buffer > as TRUNCATED. But we delay the notification to the perf layer > by perf_aux_output_end() until the event is scheduled out. via the CoreSight PMU layer's stop event ? > This will cause significant black outs in the trace. Now that > the CoreSight PMU layer can handle a closed "AUX" handle > properly, we can close the handle as soon as we detect the > case, allowing the userspace to collect and re-enable the > event. > > Also, while in the IRQ handler, move the irq_work_run() after > we have updated the handle, to make sure the "TRUNCATED" flag > causes the event to be disabled as soon as possible. Makes sense. Minor nit. Commit message here should be reformatted to be expanded upto 75 character width. > > Cc: Anshuman Khandual > Cc: Mathieu Poirier > Cc: Mike Leach > Cc: Leo Yan > Cc: Peter Zijlstra (Intel) > Cc: Will Deacon > Signed-off-by: Suzuki K Poulose > --- > drivers/hwtracing/coresight/coresight-trbe.c | 25 ++++++++++++-------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index 6d6aad171c72..e7567727e8fc 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -134,6 +134,7 @@ static void trbe_stop_and_truncate_event(struct perf_output_handle *handle) > trbe_drain_and_disable_local(); > perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED | > PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW); > + perf_aux_output_end(handle, 0); > *this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL; > } > > @@ -699,7 +700,7 @@ static void trbe_handle_spurious(struct perf_output_handle *handle) > isb(); > } > > -static void trbe_handle_overflow(struct perf_output_handle *handle) > +static int trbe_handle_overflow(struct perf_output_handle *handle) > { > struct perf_event *event = handle->event; > struct trbe_buf *buf = etm_perf_sink_config(handle); > @@ -728,10 +729,10 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) > */ > trbe_drain_and_disable_local(); > *this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL; > - return; > + return -EINVAL; > } > > - __arm_trbe_enable(buf, handle); > + return __arm_trbe_enable(buf, handle); > } > > static bool is_perf_trbe(struct perf_output_handle *handle) > @@ -762,6 +763,7 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) > struct perf_output_handle *handle = *handle_ptr; > enum trbe_fault_action act; > u64 status; > + bool truncated = false; > > /* Reads to TRBSR_EL1 is fine when TRBE is active */ > status = read_sysreg_s(SYS_TRBSR_EL1); > @@ -786,24 +788,27 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) > if (!is_perf_trbe(handle)) > return IRQ_NONE; > > - /* > - * Ensure perf callbacks have completed, which may disable > - * the trace buffer in response to a TRUNCATION flag. > - */ > - irq_work_run(); > - > act = trbe_get_fault_act(status); > switch (act) { > case TRBE_FAULT_ACT_WRAP: > - trbe_handle_overflow(handle); > + truncated = !!trbe_handle_overflow(handle); > break; > case TRBE_FAULT_ACT_SPURIOUS: > trbe_handle_spurious(handle); > break; > case TRBE_FAULT_ACT_FATAL: > trbe_stop_and_truncate_event(handle); > + truncated = true; > break; > } > + > + /* > + * If the buffer was truncated, ensure perf callbacks > + * have completed, which will disable the event. > + */ > + if (truncated) > + irq_work_run(); > + > return IRQ_HANDLED; > } > > LGTM. Reviewed-by: Anshuman Khandual