18/01/2021 16:45, Burakov, Anatoly:

On 18-Jan-21 3:24 PM, David Marchand wrote:

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On Thu, Jan 14, 2021 at 3:46 PM Anatoly Burakov
[off-list ref] wrote:

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This patchset proposes a simple API for Ethernet drivers to cause the
CPU to enter a power-optimized state while waiting for packets to
arrive. There are multiple proposed mechanisms to achieve said power
savings: simple frequency scaling, idle loop, and monitoring the Rx
queue for incoming packages. The latter is achieved through cooperation
with the NIC driver that will allow us to know address of wake up event,
and wait for writes on that address.

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Why are we putting it into ethdev as opposed to leaving this up to the
application? Our customers specifically requested a way to do it with
minimal changes to the application code. The current approach allows to
just flip a switch and automatically have power savings.

The customer laziness is usually a bad justification :)
I think we could achieve the same with not too much code
on application side.
And I'm not sure hiding queue management is sane.
Remember this rule: application must remain in control.

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SPDK build is still broken.
http://mails.dpdk.org/archives/test-report/2021-January/174840.html

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I guess this is because of the added dependency of rte_ethdev to rte_power.
Afaics, SPDK does not use pkg-config:
https://github.com/spdk/spdk/blob/master/lib/env_dpdk/env.mk#L53

Sooo... this is an SPDK issue then? Because i can't see any way of 
fixing the issue on DPDK side.

Yes SPDK should not skip pkg-config.
But it raises 2 question:
	- are we breaking ABI compatibility?
	- is ethdev management expected for librte_power?

It makes me wonder whether we should host the few functions mixing
librte_ethdev and librte_power somewhere else.
The question is where?