Re: [PATCH v1 0/2] support NUMA emulation for genertic arch

[Pierre Gondois]

On 2/21/24 07:12, Mike Rapoport wrote:
> On Tue, Feb 20, 2024 at 07:36:00PM +0800, Rongwei Wang wrote:
> > A brief introduction
> > ====================
> >
> > The NUMA emulation can fake more node base on a single
> > node system, e.g.
>
> ...
>   
> > Lastly, it seems not a good choice to realize x86 and other genertic
> > archs separately. But it can indeed avoid some architecture related
> > APIs adjustments and alleviate future maintenance.
>
> Why is it a good choice? Copying 1k lines from x86 to a new place and
> having to maintain two copies does not sound like a good choice to me.

I agree it would be better to avoid duplication and extract the common
code from the original x86 implementation. The RFC seemed to go more
in this direction.
Also NITs:
- genertic -> generic
- there is a 'ifdef CONFIG_X86' in drivers/base/numa_emulation.c,
  but the file should not be used by x86 as the arch doesn't set
  CONFIG_GENERIC_ARCH_NUMA

Regards,
Pierre

> > The previous RFC link see [1].
> >
> > Any advice are welcome, Thanks!
> >
> > Change log
> > ==========
> >
> > RFC v1 -> v1
> > * add new CONFIG_NUMA_FAKE for genertic archs.
> > * keep x86 implementation, realize numa emulation in driver/base/ for
> >    genertic arch, e.g, arm64.
> >
> > [1] RFC v1: https://patchwork.kernel.org/project/linux-arm-kernel/cover/20231012024842.99703-1-rongwei.wang@xxxxxxxxxxxxxxxxx/
> >
> > Rongwei Wang (2):
> >    arch_numa: remove __init for early_cpu_to_node
> >    numa: introduce numa emulation for genertic arch
> >
> >   drivers/base/Kconfig          |   9 +
> >   drivers/base/Makefile         |   1 +
> >   drivers/base/arch_numa.c      |  32 +-
> >   drivers/base/numa_emulation.c | 909 ++++++++++++++++++++++++++++++++++
> >   drivers/base/numa_emulation.h |  41 ++
> >   include/asm-generic/numa.h    |   2 +-
> >   6 files changed, 992 insertions(+), 2 deletions(-)
> >   create mode 100644 drivers/base/numa_emulation.c
> >   create mode 100644 drivers/base/numa_emulation.h
> >
> > --
> > 2.32.0.3.gf3a3e56d6