linux-kernel - Re: [PATCH 2/5] selftests/resctrl: Clear unused common codes called by CAT/MBA tests

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Date:   Thu, 22 Sep 2022 10:44:49 -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 2/5] selftests/resctrl: Clear unused common codes called
 by CAT/MBA tests

Hi Shaopeng,

On 9/13/2022 6:51 PM, Shaopeng Tan wrote:
> In CAT/MBA(allocation) tests, function write_schemata() is used to
> change the percentage of schemata.
> In CMT/MBM(monitoring) tests schemata only need to be set 100% once,
> and the default value of schemata is 100% which is set by executing
> mount/umout resctrl filesystem.
> In addition, write_schemata() was not currently called from CMT.

While this is all accurate it is not clear to me that this
justifies the removal of the support for changing the
schemata as part of a CMT test. 

>From what I can tell write_schemata() is a a generic function that
currently supports all possible tests. If a later update needs to use
this for a CMT test then it should work.

I do not see any harm in leaving these checks.

> 
> Clean up unused CMT-related processing in function write_schemata().
> 
> Signed-off-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> ---
>  tools/testing/selftests/resctrl/resctrlfs.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
> index 6f543e470ad4..349dce00472f 100644
> --- a/tools/testing/selftests/resctrl/resctrlfs.c
> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
> @@ -498,8 +498,7 @@ int write_schemata(char *ctrlgrp, char *schemata, int cpu_no, char *resctrl_val)
>  	FILE *fp;
>  
>  	if (strncmp(resctrl_val, MBA_STR, sizeof(MBA_STR)) &&
> -	    strncmp(resctrl_val, CAT_STR, sizeof(CAT_STR)) &&
> -	    strncmp(resctrl_val, CMT_STR, sizeof(CMT_STR)))
> +	    strncmp(resctrl_val, CAT_STR, sizeof(CAT_STR)))
>  		return -ENOENT;
>  
>  	if (!schemata) {
> @@ -520,8 +519,7 @@ int write_schemata(char *ctrlgrp, char *schemata, int cpu_no, char *resctrl_val)
>  	else
>  		sprintf(controlgroup, "%s/schemata", RESCTRL_PATH);
>  
> -	if (!strncmp(resctrl_val, CAT_STR, sizeof(CAT_STR)) ||
> -	    !strncmp(resctrl_val, CMT_STR, sizeof(CMT_STR)))
> +	if (!strncmp(resctrl_val, CAT_STR, sizeof(CAT_STR)))
>  		sprintf(schema, "%s%d%c%s", "L3:", resource_id, '=', schemata);
>  	if (!strncmp(resctrl_val, MBA_STR, sizeof(MBA_STR)))
>  		sprintf(schema, "%s%d%c%s", "MB:", resource_id, '=', schemata);

Reinette