linux-kernel - Re: [PATCH] lib: test module for find_*

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Date:   Fri, 10 Nov 2017 12:45:18 +0200
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Yury Norov <ynorov@...iumnetworks.com>,
        linux-kernel@...r.kernel.org, Clement Courbet <courbet@...gle.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH] lib: test module for find_*_bit() functions

On 11/10/17, Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Thu,  9 Nov 2017 17:07:14 +0300 Yury Norov <ynorov@...iumnetworks.com>
> wrote:
>
>> find_bit functions are widely used in the kernel, including hot paths.
>> This module tests performance of that functions in 2 typical scenarios:
>> randomly filled bitmap with relatively equal distribution of set and
>> cleared bits, and sparse bitmap which has 1 set bit for 500 cleared bits.
>>
>> ...
>>
>> +config TEST_FIND_BIT
>
> Well.  It doesn't actually "test" the code.  It measures its performance ;)

Yes!

Yyra, you can grab CONFIG_BENCHMARK_* namespace :-)


Another thing:

> +
> +       return 0;
> +}
> +module_init(find_bit_test);
> +
> +static void __exit test_find_bit_cleanup(void)
> +{
> +}
> +module_exit(test_find_bit_cleanup);

module exit hook is entirely unnecessary as you can return -E from init hook.
See lib/test-kstrtox.c