Subject: bug#42044: nproc says "1" on mobile processors

From: Adam Borowski <[email-masked]>
Date: Fri, 26 Jun 2020 21:18:57 +0200

On Fri, Jun 26, 2020 at 07:26:16PM +0100, Pádraig Brady wrote:
> On 25/06/2020 18:37, Adam Borowski wrote:
> > Hi!
> > I'm afraid that `nproc` shows only the number of _currently_ online CPUs,
> > which on mobile processors tends to be 1 when starting a job.  As there's
> > a need to conserve power, holding cores online when they have nothing to
> > do would be a waste, thus they constantly get onlined and offlined.

> > Ie, could you please make nproc include all available CPUs rather than
> > only online ones?
> 
> Does `nproc --all` suffice for your use case?

It works on the mobile box, but doesn't obey affinity mask anymore:

[~]$ numactl -N 0 nproc --all
64
[~]$ numactl -N 0 nproc 
16

I'd wish for fitting all uses, big and small.  Ie, the answer "on this
machine, with currently imposed limits, what's the fastest level of
parallelism?".

Meow.
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