linux-kernel - Re: [PATCH v9 1/6] selftests/resctrl: Fix set up schemata with 100% allocation on first run in MBM test

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Date:   Fri, 14 Apr 2023 08:24:31 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        "Shaopeng Tan" <tan.shaopeng@...fujitsu.com>
CC:     Fenghua Yu <fenghua.yu@...el.com>, Shuah Khan <shuah@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH v9 1/6] selftests/resctrl: Fix set up schemata with 100%
 allocation on first run in MBM test



On 4/14/2023 5:31 AM, Ilpo Järvinen wrote:
> On Thu, 13 Apr 2023, Shaopeng Tan wrote:
> 
>> There is a comment "Set up shemata with 100% allocation on the first run"
> 
> s/shemata/schemata/

Having the typo may be ok since this is a verbatim (typo and all) copy of
an existing comment.

>> in function mbm_setup(), but there is an increment bug and the condition
>> "num_of_runs == 0" will never be met and write_schemata() will never be
>> called to set schemata to 100%. Even if write_schemata() is called in MBM
>> test, since it is not supported for MBM test it does not set the schemata.
>> This is currently fine because resctrl_val_parm->mum_resctrlfs is always 1
>> and umount/mount will be run in each test to set the schemata to 100%.
>>
>> To support the usage when MBM test does not unmount/remount resctrl
>> filesystem before the test starts, fix to call write_schemata() and
>> set schemata properly when the function is called for the first time.
>>
>> Also, remove static local variable 'num_of_runs' because this is not
>> needed as there is resctrl_val_param->num_of_runs which should be used
>> instead like in cat_setup().
>>
>> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
>> Signed-off-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
>> ---
>>  tools/testing/selftests/resctrl/mbm_test.c  | 13 +++++++------
>>  tools/testing/selftests/resctrl/resctrlfs.c |  4 +++-
>>  2 files changed, 10 insertions(+), 7 deletions(-)
>>
>> diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/selftests/resctrl/mbm_test.c
>> index c9dfa54af42f..9b591c35310f 100644
>> --- a/tools/testing/selftests/resctrl/mbm_test.c
>> +++ b/tools/testing/selftests/resctrl/mbm_test.c
>> @@ -89,23 +89,24 @@ static int check_results(int span)
>>  static int mbm_setup(int num, ...)
>>  {
>>  	struct resctrl_val_param *p;
>> -	static int num_of_runs;
>>  	va_list param;
>>  	int ret = 0;
>>  
>> -	/* Run NUM_OF_RUNS times */
>> -	if (num_of_runs++ >= NUM_OF_RUNS)
>> -		return END_OF_TESTS;
>> -
>>  	va_start(param, num);
>>  	p = va_arg(param, struct resctrl_val_param *);
>>  	va_end(param);
>>  
>> +	/* Run NUM_OF_RUNS times */
>> +	if (p->num_of_runs >= NUM_OF_RUNS)
>> +		return -1;
> 
> This is not rebased correctly, negative return values mean now errors.
> To complete tests "normally", return END_OF_TESTS. Please see commit 
> fa10366cc6f4 ("selftests/resctrl: Allow ->setup() to return errors") for 
> future information.
> 
> With the forementioned problems fixed:
> 
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> 

Thanks for catching this. Unfortunately this was just merged so a separate
fix will be needed.

Reinette