Re: [PATCH v7 4/7] xen/cpupool: Create different cpupools at boot time

[Jan Beulich <jbeulich@xxxxxxxx>]

On 11.04.2022 17:20, Luca Fancellu wrote:
> Introduce a way to create different cpupools at boot time, this is
> particularly useful on ARM big.LITTLE system where there might be the
> need to have different cpupools for each type of core, but also
> systems using NUMA can have different cpu pools for each node.
> 
> The feature on arm relies on a specification of the cpupools from the
> device tree to build pools and assign cpus to them.
> 
> ACPI is not supported for this feature.
> 
> With this patch, cpupool0 can now have less cpus than the number of
> online ones, so update the default case for opt_dom0_max_vcpus.
> 
> Documentation is created to explain the feature.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
> ---
> Changes in v7:
> - rename xen/common/boot_cpupools.c to xen/common/sched/boot-cpupool.c (Jan)
> - reverted xen/common/Makefile, add entry in xen/common/sched/Makefile
> - changed line in MAINTAINERS under CPU POOLS section (Dario)
> - Fix documentation, update opt_dom0_max_vcpus to the number of cpu in
>   cpupool0 (Julien)
> Changes in v6:
> - Changed docs, return if booted with ACPI in btcpupools_dtb_parse,
>   panic if /chosen does not exists. Changed commit message (Julien)
> - Add Juergen R-by for the xen/common/sched part that didn't change
> Changes in v5:
> - Fixed wrong variable name, swapped schedulers, add scheduler info
>   in the printk (Stefano)
> - introduce assert in cpupool_init and btcpupools_get_cpupool_id to
>   harden the code
> Changes in v4:
> - modify Makefile to put in *.init.o, fixed stubs and macro (Jan)
> - fixed docs, fix brakets (Stefano)
> - keep cpu0 in Pool-0 (Julien)
> - moved printk from btcpupools_allocate_pools to
>   btcpupools_get_cpupool_id
> - Add to docs constraint about cpu0 and Pool-0
> Changes in v3:
> - Add newline to cpupools.txt and removed "default n" from Kconfig (Jan)
> - Fixed comment, moved defines, used global cpu_online_map, use
>   HAS_DEVICE_TREE instead of ARM and place arch specific code in header
>   (Juergen)
> - Fix brakets, x86 code only panic, get rid of scheduler dt node, don't
>   save pool pointer and look for it from the pool list (Stefano)
> - Changed data structures to allow modification to the code.
> Changes in v2:
> - Move feature to common code (Juergen)
> - Try to decouple dtb parse and cpupool creation to allow
>   more way to specify cpupools (for example command line)
> - Created standalone dt node for the scheduler so it can
>   be used in future work to set scheduler specific
>   parameters
> - Use only auto generated ids for cpupools
> ---
>  MAINTAINERS                            |   2 +-
>  docs/misc/arm/device-tree/cpupools.txt | 140 +++++++++++++++++
>  xen/arch/arm/domain_build.c            |   5 +-
>  xen/arch/arm/include/asm/smp.h         |   3 +
>  xen/common/Kconfig                     |   7 +

For consistency, should the addition here - with ...

>  xen/common/sched/Makefile              |   1 +
>  xen/common/sched/boot-cpupool.c        | 207 +++++++++++++++++++++++++
>  xen/common/sched/cpupool.c             |  12 +-

... the new file now under sched/, also be put in sched/Kconfig?

Jan