Re: DPDK and energy efficiency

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

> This is way too deep in the weeds of developing with the DPDK
> libraries for your audience here to have much in the way of useful
> comment.  This is an operators group.

Fair enough, and thank you for stepping on the brakes :)

Honestly, I didn't intend to get embroiled in this. The questions were
bare-bones and relate to common use of DPDK.

Over and out. I'll post the results on Friday evening CET.

Cheers,

Etienne

On Tue, Feb 23, 2021 at 11:38 PM William Herrin <bill () herrin us> wrote:

> On Tue, Feb 23, 2021 at 2:22 PM Etienne-Victor Depasquale
> <edepa () ieee org> wrote:
> > > 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.
>
> Howdy,
>
> This is way too deep in the weeds of developing with the DPDK
> libraries for your audience here to have much in the way of useful
> comment.  This is an operators group.
>
> If anyone is interested, the techniques DPDK offers application
> authors to manage power on the dataplane cores are described here:
>
> https://doc.dpdk.org/guides/prog_guide/power_man.html
>
> The main thing devs do, since it's easy, is add a call to rte_pause()
> in any empty polling loop. IIRC, that just calls the CPU PAUSE
> instruction which doesn't actually pause anything but saves a little
> power by de-pipelining and, if hyperthreading is enabled, releasing
> the core to run the alternate thread.
>
> 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