Re: [PATCH] mm/fake-numa: per-phys node fake size

Mike Rapoport
2024-10-01T07:18:57Z

On Sun, Sep 29, 2024 at 03:43:50PM +0000, Bruno Faccini wrote:
>
> On 25/09/2024 11:32, "Mike Rapoport" <rppt@kernel.org <mailto:rppt@kernel.org>> wrote:
> > On Tue, Sep 24, 2024 at 03:27:52PM +0000, Bruno Faccini wrote:
> > > On 24/09/2024 12:43, "Mike Rapoport" <rppt@kernel.org <mailto:rppt@kernel.org>> wrote:
> >
> > > I don't think that fake=N allocation method is intended to get fake nodes
> > > with equal size, but to get this exact number of nodes. This is why I
> > > think we should use a per-phys node size for the fake nodes it will host.
> >
> > IMO your change adds to much complexity for a feature that by definition
> > should be used only for debugging.
>
> Well it is only executed once during boot, and as you said for debugging,
> so I believe when the boot speed is not a requirement. And my testing on
> our fat Numa nodes did not show a real difference.

I meant code complexity, not the execution complexity.

> > Also, there is a variation numa=fake=<N>U of numa=fake parameter that
> > divides each node into N emulated nodes.
>
> Right, but both methods should work as expected, is'nt it ?
> And one allocates emulated nodes interleaved on physical nodes when the
> second is doing allocation serially.

I think we can just bail out with an error if we fail to create the
requested emulated nodes.