Re: [PATCH v2] selftests/resctrl: fix clang build warnings related to abs(), labs() calls
From: Reinette Chatre
Date: Tue May 07 2024 - 21:38:49 EST
Hi John,
On 5/7/2024 6:25 PM, John Hubbard wrote:
> On 5/7/24 6:21 PM, Reinette Chatre wrote:
>> Hi John,
> ...
>>
>> The following (what was in v1) looks good to me. What am I missing?
>>
>> diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c
>> index a81f91222a89..05a241519ae8 100644
>> --- a/tools/testing/selftests/resctrl/cmt_test.c
>> +++ b/tools/testing/selftests/resctrl/cmt_test.c
>> @@ -40,11 +40,11 @@ static int show_results_info(unsigned long sum_llc_val, int no_of_bits,
>> int ret;
>> avg_llc_val = sum_llc_val / num_of_runs;
>> - avg_diff = (long)abs(cache_span - avg_llc_val);
>> + avg_diff = (long)(cache_span - avg_llc_val);
>
> This deletes the abs() call, because I incorrectly let clang's warning
> lead me to believe that the abs() call was a no-op. But both you and Ilpo
> pointed out that the math breaks if you do that.
To me the extra abs() was unnecessary anyway ...
>
>> diff_percent = ((float)cache_span - avg_llc_val) / cache_span * 100;
>> ret = platform && abs((int)diff_percent) > max_diff_percent &&
>> - abs(avg_diff) > max_diff;
>> + labs(avg_diff) > max_diff;
>
.. because it is repeated here.
> This hunk is OK.
>
>> ksft_print_msg("%s Check cache miss rate within %lu%%\n",
>> ret ? "Fail:" : "Pass:", max_diff_percent);
>>
>> Reinette
>
> thanks,
Reinette