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

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Message-ID: <TYAPR01MB6330740D4D21CE76B22496258B559@TYAPR01MB6330.jpnprd01.prod.outlook.com>
Date:   Tue, 27 Sep 2022 09:01:34 +0000
From:   "tan.shaopeng@...itsu.com" <tan.shaopeng@...itsu.com>
To:     'Reinette Chatre' <reinette.chatre@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Shuah Khan <shuah@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-kselftest@...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 Reinette,

> 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.

According to my research, whether clearing this code or not has no effect on the current program.
I cleared this code because it looks redundant. Because CMT test didn't call write_schemata().
I will remove this patch in the next version.

Best Regards,
Shaopeng

> >
> > 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