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Tue, 31 Mar 2026 12:13:05 -0700 (PDT) Received: from [192.168.1.14] ([38.175.187.108]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-67e2305db5dsm7419592eaf.4.2026.03.31.12.13.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 31 Mar 2026 12:13:05 -0700 (PDT) Message-ID: <17b0f9ea-ea81-489c-8a8b-f3118d3d28f3@linuxfoundation.org> Date: Tue, 31 Mar 2026 13:13:03 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 00/10] selftests/resctrl: Fixes and improvements focused on Intel platforms To: Reinette Chatre , shuah@kernel.org, Dave.Martin@arm.com, james.morse@arm.com, tony.luck@intel.com, babu.moger@amd.com, ilpo.jarvinen@linux.intel.com Cc: fenghuay@nvidia.com, peternewman@google.com, zide.chen@intel.com, dapeng1.mi@linux.intel.com, ben.horgan@arm.com, yu.c.chen@intel.com, jason.zeng@intel.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Shuah Khan References: Content-Language: en-US From: Shuah Khan In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/13/26 14:32, Reinette Chatre wrote: > Changes since v2: > - v2: https://lore.kernel.org/linux-patches/cover.1772582958.git.reinette.chatre@intel.com/ > - Rebased on top of v7.0-rc3. > - Split "selftests/resctrl: Improve accuracy of cache occupancy test" into > changes impacting L3 and L2 respectively. (Ilpo) > - "long_mask" -> "full_mask", "return_value" -> "measurement", "org_count" > -> "orig_count". (Ilpo) > - Use PATH_MAX where appropriate. (Ilpo) > - Handle errors first to reduce indentation. (Ilpo) > - Detailed changes in changelogs. > - No functional changes since v2. Series tested by running 20 iterations of all > tests on Emerald Rapids, Granite Rapids, Sapphire Rapids, Ice Lake, Sierra > Forest, and Broadwell. > > Changes since v1: > - v1: https://lore.kernel.org/lkml/cover.1770406608.git.reinette.chatre@intel.com/ > - The new perf interface that resctrl selftests can utilize has been accepted and > merged into v7.0-rc2. This series can thus now be considered for inclusion. > For reference, > commit 6a8a48644c4b ("perf/x86/intel/uncore: Add per-scheduler IMC CAS count events") > The resctrl selftest changes making use of the new perf interface are backward > compatible. The selftests do not require a v7.0-rc2 kernel to run but the > tests can only pass on recent Intel platforms running v7.0-rc2 or later. > - Combine the two outstanding resctrl selftest submissions into one series > for easier tracking: > https://lore.kernel.org/lkml/084e82b5c29d75f16f24af8768d50d39ba0118a5.1769101788.git.reinette.chatre@intel.com/ > https://lore.kernel.org/lkml/cover.1770406608.git.reinette.chatre@intel.com/ > - Fix typo in changelog of "selftests/resctrl: Improve accuracy of cache > occupancy test": "the data my be in L2" -> "the data may be in L2" > - Add Zide Chen's RB tags. > > Cover letter updated to be accurate wrt perf changes: > > The resctrl selftests fail on recent Intel platforms. Intermittent failures > in the CAT test and permanent failures of MBM and MBA tests on new platforms > like Sierra Forest and Granite Rapids. > > The MBM and MBA resctrl selftests both generate memory traffic and compare the > memory bandwidth measurements between the iMC PMUs and MBM to determine pass or > fail. Both these tests are failing on recent platforms like Sierra Forest and > Granite Rapids that have two events that need to be read and combined > for a total memory bandwidth count instead of the single event available on > earlier platforms. > > resctrl selftests prefer to obtain event details via sysfs instead of adding > model specific details on which events to read. Enhancements to perf to expose > the new event details are available since: > commit 6a8a48644c4b ("perf/x86/intel/uncore: Add per-scheduler IMC CAS count events") > This series demonstrates use of the new sysfs interface to perf > to obtain accurate iMC read memory bandwidth measurements. > > An additional issue with all the tests is that these selftests are part > performance tests and determine pass/fail on performance heuristics selected > after running the tests on a variety of platforms. When new platforms > arrive the previous heuristics may cause the tests to fail. These failures are > not because of an issue with the resctrl subsystem the tests intend to test > but because of the architectural changes in the new platforms. > > Adapt the resctrl tests to not be as sensitive to architectural changes > while adjusting the remaining heuristics to ensure tests pass on a variety > of platforms. More details in individual patches. > > Tested by running 100 iterations of all tests on Emerald Rapids, Granite > Rapids, Sapphire Rapids, Ice Lake, Sierra Forest, and Broadwell. > > Reinette Chatre (10): > selftests/resctrl: Improve accuracy of cache occupancy test > selftests/resctrl: Reduce interference from L2 occupancy during cache > occupancy test > selftests/resctrl: Do not store iMC counter value in counter config > structure > selftests/resctrl: Prepare for parsing multiple events per iMC > selftests/resctrl: Support multiple events associated with iMC > selftests/resctrl: Increase size of buffer used in MBM and MBA tests > selftests/resctrl: Raise threshold at which MBM and PMU values are > compared > selftests/resctrl: Remove requirement on cache miss rate > selftests/resctrl: Simplify perf usage in CAT test > selftests/resctrl: Reduce L2 impact on CAT test > Let me know if this series is ready to go into Linux 7.1 thanks, -- Shuah