linux-kernel - Re: [PATCH 05/24] selftests/resctrl: Create cache

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Message-ID: <3849d986-caf4-41ad-85c7-11f11f986e1c@intel.com>
Date:   Thu, 2 Nov 2023 10:47:33 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        <linux-kselftest@...r.kernel.org>, Shuah Khan <shuah@...nel.org>,
        "Shaopeng Tan" <tan.shaopeng@...fujitsu.com>,
        Maciej Wieczór-Retman 
        <maciej.wieczor-retman@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 05/24] selftests/resctrl: Create cache_size() helper

Hi Ilpo,

On 10/24/2023 2:26 AM, Ilpo Järvinen wrote:
> CAT and CMT tests calculate the span size from the n-bits cache
> allocation on their own.
> 
> Add cache_size() helper which calculates size of the cache portion for
> the given number of bits and use it to replace the existing span
> calculations. This also prepares for the new CAT test that will need to
> determine the size of the cache portion also during results processing.
> 
> cache_size local variables were renamed out of the way to
> cache_total_size.

Please do stick to imperative mood ... "Rename cache_size local
variables ..."


...

> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index 2f3f0ee439d8..da06b2d492f9 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -117,4 +117,18 @@ int show_cache_info(unsigned long sum_llc_val, int no_of_bits,
>  		    unsigned long max_diff_percent, unsigned long num_of_runs,
>  		    bool platform, bool cmt);
>  
> +/*
> + * cache_size - Calculate the size of a cache portion
> + * @cache_size:	Cache size in bytes
> + * @mask:	Cache portion mask
> + * @cache_mask:	Full bitmask for the cache
> + *
> + * Return: The size of the cache portion in bytes.
> + */
> +static inline int cache_size(unsigned long cache_size, unsigned long mask,
> +			     unsigned long cache_mask)
> +{
> +	return cache_size * count_bits(mask) / count_bits(cache_mask);
> +}
> +
>  #endif /* RESCTRL_H */


The get_cache_size() and cache_size() naming appears similar enough to me
to cause confusion. Considering the "portion" term above, what do you think
of "cache_portion_size()" or even "cache_portion_bytes()"?

Reinette