Re: [dpdk-dev] [PATCH v9 04/10] ethdev: add simple power management API

[Thomas Monjalon <thomas@monjalon.net>]

27/10/2020 18:43, Ananyev, Konstantin:
> > 27/10/2020 12:15, Liang, Ma:
> > > > > --- a/lib/librte_ethdev/rte_ethdev.h
> > > > > +++ b/lib/librte_ethdev/rte_ethdev.h
> > > > > +/**
> > > > > + * Retrieve the wake up address for the receive queue.
> > > >
> > > > I guess how this function should be used,
> > > > but a bit more explanations would not hurt here.
> > > agree
> > > > > + *
> > > > > + * @param port_id
> > > > > + *   The port identifier of the Ethernet device.
> > > > > + * @param queue_id
> > > > > + *   The Rx queue on the Ethernet device for which information will be
> > > > > + *   retrieved.
> > > > > + * @param wake_addr
> > > > > + *   The pointer to the address which will be monitored.
> > > >
> > > > This function does not make the address monitored, right?
> > > This function only get the target wakeup address. that does not monitor this address.
> > > >
> > > > > + * @param expected
> > > > > + *   The pointer to value to be expected when descriptor is set.
> > > >
> > > > Not sure we should restrict it to a "descriptor".
> > >   actully that is not limited to a descriptor, any writeback content should work.
> > > >
> > > > Expecting a value or some bits looks too much restrictive.
> > > > I understand it probably fits well for Intel NICs,
> > > > but in the general case, we can imagine that any change
> > > > in a byte array could be a wake up signal.
> > >
> > > this parameter doesn not limited user how to use it.
> > > In fact, current design can support any bits change within 64 bits content.
> > 
> > How the driver can specify that any value change should be monitored?
> > I understand that it is only a value/mask pair,
> > it does not give room for "any value".
> 
> As I can read the code, value=0, mask=0 will provide you with 'any value'.
> Though it would mean that rte_power_monitor() will *always* go into sleep,
> so not sure what will be there any practical usage for such case. 

I think what is missing is to allow waking up when the value
of a byte array is changing, without specifiying any value.