linux-kernel - Re: [PATCH v7 12/13] selftests/resctrl: Disable MBA and MBM tests for AMD

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Message-ID: <20190510184011.210794fc@donnerap.cambridge.arm.com>
Date:   Fri, 10 May 2019 18:40:11 +0100
From:   Andre Przywara <andre.przywara@....com>
To:     Fenghua Yu <fenghua.yu@...el.com>
Cc:     "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
        "H Peter Anvin" <hpa@...or.com>, "Tony Luck" <tony.luck@...el.com>,
        "Reinette Chatre" <reinette.chatre@...el.com>,
        "Ravi V Shankar" <ravi.v.shankar@...el.com>,
        "Xiaochen Shen" <xiaochen.shen@...el.com>,
        "Arshiya Hayatkhan Pathan" <arshiya.hayatkhan.pathan@...el.com>,
        "Sai Praneeth Prakhya" <sai.praneeth.prakhya@...el.com>,
        "Babu Moger" <babu.moger@....com>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        James Morse <James.Morse@....com>
Subject: Re: [PATCH v7 12/13] selftests/resctrl: Disable MBA and MBM tests
 for AMD

On Sat,  9 Feb 2019 18:50:41 -0800
Fenghua Yu <fenghua.yu@...el.com> wrote:

Hi,

> From: Babu Moger <babu.moger@....com>
> 
> For now, disable MBA and MBM tests for AMD. Deciding test pass/fail
> is not clear right now. We can enable when we have some clarity.

I don't think this is the right way. The availability of features should
be queryable, for instance by looking into /sys/fs/resctrl/info. Checking
for a certain vendor to skip tests just sounds wrong to me, and is
definitely not scalable or future proof.

We should really check the availability of a feature, then skip the whole
subsystem test in resctrl_tests.c.

Cheers,
Andre.

> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> ---
>  tools/testing/selftests/resctrl/cat_test.c      | 2 +-
>  tools/testing/selftests/resctrl/resctrl_tests.c | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index 1a0f77e4f7bf..264bf2325f9e 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -69,7 +69,7 @@ static void show_cache_info(unsigned long sum_llc_perf_miss, int no_of_bits,
>  	printf("Allocated cache lines: %lu \t", allocated_cache_lines);
>  	printf("Percent diff=%d \t", abs((int)diff_percent));
>  
> -	if (abs((int)diff_percent) > MAX_DIFF_PERCENT)
> +	if (genuine_intel && (abs((int)diff_percent) > MAX_DIFF_PERCENT))
>  		printf("Failed\n");
>  	else
>  		printf("Passed\n");
> diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
> index 1d9adcfbdb4c..620be40b8c01 100644
> --- a/tools/testing/selftests/resctrl/resctrl_tests.c
> +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> @@ -197,7 +197,7 @@ int main(int argc, char **argv)
>  	sprintf(bw_report, "reads");
>  	sprintf(bm_type, "fill_buf");
>  
> -	if (mbm_test) {
> +	if (genuine_intel && mbm_test) {
>  		printf("\nMBM BW Change Starting..\n");
>  		if (!has_ben)
>  			sprintf(benchmark_cmd[5], "%s", "mbm");
> @@ -207,7 +207,7 @@ int main(int argc, char **argv)
>  		mbm_test_cleanup();
>  	}
>  
> -	if (mba_test) {
> +	if (genuine_intel && mba_test) {
>  		printf("\nMBA Schemata Change Starting..\n");
>  		if (!has_ben)
>  			sprintf(benchmark_cmd[5], "%s", "mba");