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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id ny4-20020a056214398400b005e37909a7fcsm2022912qvb.13.2023.04.03.23.23.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Apr 2023 23:23:18 -0700 (PDT) Message-ID: <968a026e-066e-deea-d02f-f64133295ff1@redhat.com> Date: Tue, 4 Apr 2023 08:23:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Reply-To: eric.auger@redhat.com Subject: Re: [kvm-unit-tests PATCH 0/6] arm: pmu: Fix random failures of pmu-chain-promotion Content-Language: en-US To: eric.auger.pro@gmail.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, andrew.jones@linux.dev, maz@kernel.org, will@kernel.org, oliver.upton@linux.dev, ricarkol@google.com, reijiw@google.com, alexandru.elisei@arm.com References: <20230315110725.1215523-1-eric.auger@redhat.com> From: Eric Auger In-Reply-To: <20230315110725.1215523-1-eric.auger@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi, On 3/15/23 12:07, Eric Auger wrote: > On some HW (ThunderXv2), some random failures of > pmu-chain-promotion test can be observed. > > pmu-chain-promotion is composed of several subtests > which run 2 mem_access loops. The initial value of > the counter is set so that no overflow is expected on > the first loop run and overflow is expected on the second. > However it is observed that sometimes we get an overflow > on the first run. It looks related to some variability of > the mem_acess count. This variability is observed on all > HW I have access to, with different span though. On > ThunderX2 HW it looks the margin that is currently taken > is too small and we regularly hit failure. > > although the first goal of this series is to increase > the count/margin used in those tests, it also attempts > to improve the pmu-chain-promotion logs, add some barriers > in the mem-access loop, clarify the chain counter > enable/disable sequence. > > A new 'pmu-memaccess-reliability' is also introduced to > detect issues with MEM_ACCESS event variability and make > the debug easier. > > Obviously one can wonder if this variability is something normal > and does not hide any other bug. I hope this series will raise > additional discussions about this. > > https://github.com/eauger/kut/tree/pmu-chain-promotion-fixes-v1 Gentle ping. Thanks Eric > > Eric Auger (6): > arm: pmu: pmu-chain-promotion: Improve debug messages > arm: pmu: pmu-chain-promotion: Introduce defines for count and margin > values > arm: pmu: Add extra DSB barriers in the mem_access loop > arm: pmu: Fix chain counter enable/disable sequences > arm: pmu: Add pmu-memaccess-reliability test > arm: pmu-chain-promotion: Increase the count and margin values > > arm/pmu.c | 189 +++++++++++++++++++++++++++++++++------------- > arm/unittests.cfg | 6 ++ > 2 files changed, 141 insertions(+), 54 deletions(-) >