Re: [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs

[H. Peter Anvin]

Stupid thought... do we have cases that matter where the bias and default don't agree?

Ingo Molnar <mingo@xxxxxxx> wrote:

>
>* Ingo Molnar <mingo@xxxxxxx> wrote:
>
>> But it is fundamentally mixing execution and *data type* and 
>> it is not conveying the build time bias properly.
>> 
>> So the best high level naming would be something like:
>> 
>> 	struct static_condition static_flag = STATIC_COND_FALSE;
>> 
>> 
>> 	if (very_unlikely(&static_flag)) {
>> 		...
>> 	}
>> 
>> 	...
>> 
>> 	static_cond_inc(&static_flag);
>> 	...
>> 	static_cond_dec(&static_flag);
>
>Btw., I think the modification path could also carry the high 
>cost of modification (stopping all cpus, modifying code, etc.).
>
>This could be done via:
>
>	static_cond_slow_inc(&static_flag);
>	...
>	static_cond_slow_dec(&static_flag);
>
>And if a developer does not notice that 'slow' implies a 
>performance cost, then he probably would have doubly missed this 
>aspect of jump_label_inc()/jump_label_dec().
>
>Thanks,
>
>	Ingo

-- 
Sent from my mobile phone. Please excuse my brevity and lack of formatting.
--
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/