Re: [PATCH] perf diff: Report noisy for cycles diff

[Jin, Yao]

On 7/16/2019 4:51 PM, Jiri Olsa wrote:
> On Fri, Jul 12, 2019 at 03:53:55PM +0800, Jin Yao wrote:
> > This patch prints the stddev and hist for the cycles diff of
> > program block. It can help us to understand if the cycles diff
> > is noisy or not.
>
> I'm getting compile error:
>
>    CC       builtin-diff.o
> builtin-diff.c: In function âcompute_cycles_diffâ:
> builtin-diff.c:712:10: error: taking the absolute value of unsigned type âu64â {aka âlong unsigned intâ} has no effect [-Werror=absolute-value]
>    712 |          labs(pair->block_info->cycles_spark[i] -
>        |          ^~~~
> cc1: all warnings being treated as errors
> mv: cannot stat './.builtin-diff.o.tmp': No such file or directory

Oh, sorry about that. My gcc (gcc version 7.4.0 (Ubuntu 
7.4.0-1ubuntu1~18.04.1)) didn't report this error. :(

u64 - u64 is u64. I should define it as s64.

Thanks for reminding me.

Thanks
Jin Yao

> jirka