Re: [PATCH 1/5] selftests/resctrl: Clear unused initalization code in MBM tests

From: Reinette Chatre
Date: Thu Sep 22 2022 - 13:44:17 EST


Hi Shaopeng,

(typo in Subject: initalization -> initialization)

On 9/13/2022 6:51 PM, Shaopeng Tan wrote:
> There is a comment "Set up shemata with 100% allocation on the first run"
> in function mbm_setup(), but the condition "num_of_runs == 0" will
> never be met and write_schemata() will never be called to set schemata
> to 100%.

Thanks for catching this.

>
> Since umount/mount resctrl file system is run on each resctrl test,
> at the same time the default schemata will also be set to 100%.

This is the case when a test is run with struct
resctrl_val_param->mum_resctrlfs == 1, but if the test is run with
struct
resctrl_val_param->mum_resctrlfs == 0 then resctrl filesystem will
not be remounted.

I do think that this setup function should support both cases.

>
> Clear unused initialization code in MBM test, such as CMT test.

Could the initialization code be fixed instead to increment
the number of runs later, similar to cat_setup()?

>
> Signed-off-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> ---
> tools/testing/selftests/resctrl/mbm_test.c | 17 ++++++-----------
> 1 file changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/selftests/resctrl/mbm_test.c
> index 8392e5c55ed0..38a3b3ad1c76 100644
> --- a/tools/testing/selftests/resctrl/mbm_test.c
> +++ b/tools/testing/selftests/resctrl/mbm_test.c
> @@ -89,24 +89,19 @@ 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 -1;
>
> va_start(param, num);
> p = va_arg(param, struct resctrl_val_param *);
> va_end(param);
>
> - /* Set up shemata with 100% allocation on the first run. */
> - if (num_of_runs == 0)
> - ret = write_schemata(p->ctrlgrp, "100", p->cpu_no,
> - p->resctrl_val);
> + /* Run NUM_OF_RUNS times */
> + if (p->num_of_runs >= NUM_OF_RUNS)
> + return -1;

You seem to be fixing two bugs in this patch, the first is described in the
commit message and the second is to use p->num_of_runs instead of the
local num_of_runs. Although, after a quick look I cannot see if
struct resctrl_val_param->num_of_runs is used anywhere. Could you
please add description of these changes to the changelog?

> +
> + p->num_of_runs++;
>
> - return ret;
> + return 0;
> }
>
> void mbm_test_cleanup(void)

Thank you

Reinette