linux-kernel - Re: [PATCH 2/4] selftests/resctrl: Don't hard code divisor in MBM results

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Date:   Tue, 14 Feb 2023 09:01:36 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC:     <linux-kselftest@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH 2/4] selftests/resctrl: Don't hard code divisor in MBM
 results

Hi Ilpo,

On 2/14/2023 2:00 AM, Ilpo Järvinen wrote:
> On Mon, 13 Feb 2023, Reinette Chatre wrote:
>> On 2/8/2023 1:40 AM, Ilpo Järvinen wrote:
>>> From: Fenghua Yu <fenghua.yu@...el.com>
>>>
>>> Presently, while calculating MBM results, the divisor is hard coded as 4.
>>
>> "Presently" can be removed. Here and in the rest of the series the usage of
>> "presently" and "currently" can usually be removed to improve clarity.
>>
>>> It's hard coded to 4 because "NUM_OF_RUNS" is defined as 5 and the test
>>> does not count first result and hence 4. So, instead of hard coding the
>>> value to 4, change it to NUM_OF_RUNS - 1.
>>
>> Are there any plans surrounding using struct resctrl_val_param::num_of_runs
>> instead?
> 
> Actually no.
> 
> What I'd want to do is that the functions which call these result 
> calculator functions would specify the number of tests they passed
> into the result calculator. It seems safer because the results are read 

Would it not simplify things to pass the test parameters (struct resctrl_val_param)
to the result calculator? That contains the number of tests run and would
reign in the hard coding.

> back from a file which could have changed (or got deleted due to an 
> ipc bug prematurely cleaning up the file) and would better take account 
> those cases where the first value is skipped when reading the results.
> 

This sounds good. Thank you.

Reinette