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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 D3697C4338F for ; Fri, 23 Jul 2021 13:45:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ADFD860EBD for ; Fri, 23 Jul 2021 13:45:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235160AbhGWNFP (ORCPT ); Fri, 23 Jul 2021 09:05:15 -0400 Received: from foss.arm.com ([217.140.110.172]:46398 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233486AbhGWNFO (ORCPT ); Fri, 23 Jul 2021 09:05:14 -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 AEE3BD6E; Fri, 23 Jul 2021 06:45:47 -0700 (PDT) Received: from [10.57.36.145] (unknown [10.57.36.145]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2CFAC3F694; Fri, 23 Jul 2021 06:45:46 -0700 (PDT) Subject: Re: [PATCH v2 00/10] coresight: TRBE and Self-Hosted trace fixes To: 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, anshuman.khandual@arm.com, jinlmao@qti.qualcomm.com References: <20210723124611.3828908-1-suzuki.poulose@arm.com> From: Suzuki K Poulose Message-ID: <78d0f297-52b6-cd8d-1406-e646d5af2898@arm.com> Date: Fri, 23 Jul 2021 14:45:44 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210723124611.3828908-1-suzuki.poulose@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/07/2021 13:46, Suzuki K Poulose wrote: > This series fixes the following issues with the TRBE and Self-Hosted > trace for CoreSight. > > The Self-hosted trace filter control registers are now save-restored > across CPU PM event. And more importantly the Trace Filtering is now > used to control per ETM session (rather than allowing the trace > throughout the life time of the system). i.e, ETM configuration of > the given run is used to enforce trace filtering (TRFCR) along with the > Trace Exclusion controls in TRCVICTLR. > > For the TRBE, we were using the TRUNCATED flag in the AUX buffer on > every IRQ to indicate that we may have lost a few bytes of trace. But > this causes the event to be disabled until the userspace re-enables > it back, even when there is space left in the ring buffer. To make > things worse, we were restarting the AUX handle, which would soon > be disabled, potentially creating 0 sized records (without truncation), > which the perf tool tends to ignore. This might cause the event to be > disabled permanently. Also, sometimes we leave the buffer TRUNCATED, > but delay the closing of the handle to event schedule out, which could > cause significant black out in the trace capture. This was reported > by Tamas Zsoldos. > > This series removes the use of TRUNCATED flag for every IRQ. Instead, > it is only used if we really run out of space in the buffer. And also > we make sure the "handle" is closed immediately on TRUNCATED case, > which triggers the userspace to take action. The core perf layer has > been hardened to handle this case where a "handle" is closed out. > Finally, we make sure that the CPU trace is prohibited, when the TRBE > is left disabled. The ETE/ETM driver will program the Trace Filtering > appropriately since we do this dynamically now with the first half > of the series. > > The series is also available here : https://git.gitlab.arm.com/linux-arm/linux-skp.git coresight/trbe-self-hosted-fixes/v2 Suzuki