Cache topology aware scheduling

[Francesco Nigro]

Hi @Danny Thomas <dannyt at netflix.com>

We're working (nudge nudge Andrew Haley) on a custom scheduler API - as
mentioned by Alan, which enables (expert) users/framework devs to implement
something like this - and more :)

Cheers,
Franz



Il giorno lun 2 set 2024 alle ore 10:41 Alan Bateman <
alan.bateman at oracle.com> ha scritto:

> On 02/09/2024 07:23, Danny Thomas wrote:
> > Hi folks,
> >
> > I was giving some thought to our adoption of Xen 4 coinciding with
> > virtual threads being available, and it occurred to me with an
> > increasing number of architectures clustering L3 and L2 caches between
> > groups of cores on a die, that virtual threads scheduling in user
> > space could make them particularly well suited to these architectures,
> > if the scheduler were topology aware.
> >
> > Have you given any thought to worker CPU affinity and/or locality to
> > an existing worker when a virtual thread is started by another? Would
> > you consider this something to be proved out by custom schedulers, or
> > is this enough of a trend to justify future investment in the default
> > scheduler?
>
> To date, we've put CPU and node affinity into the "custom scheduler"
> topic, which is still TBD on whether to expose. If you have data from
> any experiments with the current EA builds then it would be useful to
> see. The current EA builds allow the the default FJP based scheduler to
> be replaced for experimentation purposes.
>
> In a system with a mix of schedulers then starting a virtual thread will
> "inherit" the scheduler when not configured. That seems a sensible default.
>
> -Alan
>
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