Re: DPDK and energy efficiency

[Etienne-Victor Depasquale <edepa () ieee org>]

> DPDK doesn't inherently do much in the way of power management.
I agree - it doesn't. That's not what it was made for.

 Note that DPDK applications are usually intended to run in very-high

data rate environments where no gains are likely to be realized by
avoiding a busy-wait loop.

That's not what research shows.

Use of LPI states is proposed for power management under high data rate
conditions in [5] and
in [6], use of the low-power instruction *halt * is investigated and found
to save power under such conditions.

Cheers,

Etienne

[3] X. Li, W. Cheng, T. Zhang, F. Ren, and B. Yang, “Towards Power
Efficient High Performance Packet I/O,”
IEEE Transactions on Parallel and Distributed Systems, vol. 31, no. 4, pp.
981–996, April 2020,
ISSN:1558-2183. DOI: 10.1109/TPDS.2019.2957746

[5] R. Bolla, R. Bruschi, F. Davoli, and J. F. Pajo, “A Model-Based
Approach Towards Real-Time Analytics in NFV Infrastructures,”
IEEE Transactions on Green Communications and Networking, vol. 4, no. 2,
pp. 529–541, Jun. 2020, ISSN: 2473-2400.
DOI: 10.1109/TGCN.2019.2961192.


On Tue, Feb 23, 2021 at 11:04 PM William Herrin <bill () herrin us> wrote:

> On Mon, Feb 22, 2021 at 11:24 PM Etienne-Victor Depasquale
> <edepa () ieee org> wrote:
> > > Beyond RX/TX CPU affinity, in DANOS you can further tune power
> consumption by changing the adaptive polling rate.  It doesn’t, per the
> survey, "keep utilization at 100% regardless of packet activity.”
> > Robert, you seem to be conflating DPDK
> > with DANOS' power control algorithms that modulate DPDK's default
> behaviour.
> > Keep in mind that this is a bare-bones survey intended for busy,
> knowledgeable people (the ones you'd find on NANOG) -
>
> Hi,
>
> Since you understand that, I'm not really clear what you're asking in
> the survey.
>
> DPDK doesn't inherently do much in the way of power management. The
> polling loops are in the application side of the software, not the
> DPDK libraries or NIC driver. It's up to the application author to
> decide to detect idleness in the polling loop and take action to
> reduce CPU load. If they go for a simple busy-wait, the dataplane
> cores run at 100% all the time regardless of packet load. This has the
> expected impact on the server's power consumption.
>
> Note that DPDK applications are usually intended to run in very-high
> data rate environments where no gains are likely to be realized by
> avoiding a busy-wait loop.
>
> Regards,
> Bill Herrin
>
>
> --
> William Herrin
> bill () herrin us
> https://bill.herrin.us/


-- 
Ing. Etienne-Victor Depasquale
Assistant Lecturer
Department of Communications & Computer Engineering
Faculty of Information & Communication Technology
University of Malta
Web. https://www.um.edu.mt/profile/etiennedepasquale