[dpdk-dev] [PATCH v17 03/11] eal: change API of power intrinsics

[Burakov, Anatoly]

On 19-Jan-21 10:42 AM, Thomas Monjalon wrote:
> 19/01/2021 11:29, Burakov, Anatoly:
>> On 18-Jan-21 10:26 PM, Thomas Monjalon wrote:
>>> 14/01/2021 15:46, Anatoly Burakov:
>>>> +struct rte_power_monitor_cond {
>>>> +	volatile void *addr;  /**< Address to monitor for changes */
>>>> +	uint64_t val;         /**< Before attempting the monitoring, the address
>>>> +	                       *   may be read and compared against this value.
>>>
>>> "may" be read and compared?
>>> Is there a case where there is no read and compare?
>>
>> Yes, if the mask is not set.
> 
> If the mask is not set, the address is "read" anyway
> or it is only "watched" for any change?
> 
> Sorry the mechanism is really not clear to me.
> 

The "value" is only used to avoid the sleep, i.e. to check if the write 
has already happened. We're waiting on *a write* rather than *a value*, 
so it's not equivalent to "wait until equal" call. It's more of a "sleep 
until something happens".

-- 
Thanks,
Anatoly