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Fri, 27 Mar 2026 23:23:40 +0000 Message-ID: <71fe5d8c-3ff1-40ee-b4de-522a5a7b4195@intel.com> Date: Fri, 27 Mar 2026 16:22:29 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 10/10] selftests/resctrl: Reduce L2 impact on CAT test To: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= CC: , , , , , , , , , , , , , LKML , References: From: Reinette Chatre Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MW4PR04CA0247.namprd04.prod.outlook.com (2603:10b6:303:88::12) To SJ2PR11MB7573.namprd11.prod.outlook.com (2603:10b6:a03:4d2::10) Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB7573:EE_|CYXPR11MB8711:EE_ X-MS-Office365-Filtering-Correlation-Id: 609a3a0a-a763-4b3f-d2d3-08de8c57e11c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|1800799024|376014|366016|56012099003|22082099003|18002099003; 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When loading the buffer it can be >> assumed that a portion of the buffer will be loaded into the L2 cache and >> depending on cache design may not be present in L3. It is thus possible >> for data to not be in L3 but also not trigger an L3 cache miss when >> accessed. >> >> Reduce impact of L2 on the L3 CAT test by, if L2 allocation is supported, >> minimizing the portion of L2 that the workload can allocate into. This >> encourages most of buffer to be loaded into L3 and support better >> comparison between buffer size, cache portion, and cache misses when >> accessing the buffer. >> >> Signed-off-by: Reinette Chatre >> Tested-by: Chen Yu >> --- >> Changes since v2: >> - Add Chen Yu's tag. >> --- >> tools/testing/selftests/resctrl/cat_test.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c >> index 6aac03147d41..371a2f26dc47 100644 >> --- a/tools/testing/selftests/resctrl/cat_test.c >> +++ b/tools/testing/selftests/resctrl/cat_test.c >> @@ -157,6 +157,10 @@ static int cat_test(const struct resctrl_test *test, >> if (ret) >> goto reset_affinity; >> >> + ret = minimize_l2_occupancy(test, uparams, param); >> + if (ret) >> + goto reset_affinity; >> + >> perf_event_attr_initialize(&pea, PERF_COUNT_HW_CACHE_MISSES); >> pe_fd = perf_open(&pea, bm_pid, uparams->cpu); >> if (pe_fd < 0) { >> > > Reviewed-by: Ilpo Järvinen > Thank you very much for this and all the other reviews. Much appreciated. Reinette