Re: [tip:perf/core] perf/x86/intel: Clean-up/reduce PEBS code

[Andi Kleen]

tip-bot for Peter Zijlstra <tipbot@xxxxxxxxx> writes:
> +
> +	at  = (struct pebs_record_nhm *)(unsigned long)ds->pebs_buffer_base;
> +	top = (struct pebs_record_nhm *)(unsigned long)ds->pebs_index;
>  
>  	ds->pebs_index = ds->pebs_buffer_base;
>  
> +	n = (top - at) / x86_pmu.pebs_record_size;


This adds a full slow division to the PEBS hot path.

Does not seem like a improvement to me.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/