linux-kernel - Re: [PATCH v4 2/2] selftests/resctrl: Print a message if the result of MBM&CMT tests is failed on Intel cpu

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Date:   Fri, 18 Mar 2022 13:11:26 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Shuah Khan <shuah@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] selftests/resctrl: Print a message if the result
 of MBM&CMT tests is failed on Intel cpu

Hi Shaopeng Tan, 

Please use capitalization for CPU (in subject).

On 3/15/2022 10:59 PM, Shaopeng Tan wrote:
> According to "Intel Resource Director Technology (Intel RDT) on
> 2nd Generation Intel Xeon Scalable Processors Reference Manual",
> When the Intel Sub-NUMA Clustering(SNC) feature is enabled,
> Intel CMT and MBM counters may not be accurate.
> 
> However, there does not seem to be an architectural way to detect
> if SNC is enabled.
> 
> If the result of MBM&CMT test fails on Intel CPU,
> print a message to let users know a possible cause of failure.
> 
> Signed-off-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> ---
>  tools/testing/selftests/resctrl/resctrl_tests.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
> index dc548d3e2454..97ad6cfee6ee 100644
> --- a/tools/testing/selftests/resctrl/resctrl_tests.c
> +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> @@ -86,6 +86,8 @@ static void run_mbm_test(bool has_ben, char **benchmark_cmd, int span,
>  		sprintf(benchmark_cmd[5], "%s", MBA_STR);
>  	res = mbm_bw_change(span, cpu_no, bw_report, benchmark_cmd);
>  	ksft_test_result(!res, "MBM: bw change\n");
> +	if ((get_vendor() == ARCH_INTEL) && res)
> +		ksft_print_msg("Intel MBM may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");
>  	mbm_test_cleanup();
>  }
>  
> @@ -122,6 +124,8 @@ static void run_cmt_test(bool has_ben, char **benchmark_cmd, int cpu_no)
>  		sprintf(benchmark_cmd[5], "%s", CMT_STR);
>  	res = cmt_resctrl_val(cpu_no, 5, benchmark_cmd);
>  	ksft_test_result(!res, "CMT: test\n");
> +	if ((get_vendor() == ARCH_INTEL) && res)
> +		ksft_print_msg("Intel CMT may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");
>  	cmt_test_cleanup();
>  }
>  

Thank you very much for adding this.

Acked-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette