[PATCH V2 0/2] Add complex scheduler level for arm64

From: 王擎
Date: Tue Apr 26 2022 - 03:05:27 EST

Hi Sudeep:

I am thinking if it is possible to add a complex level cpu topology
between cluster and SMT?

We can describe it directly in “cpu-map”, instead of parsing it through
the cache info.


>>> From: Wang Qing <wangqing@xxxxxxxx>
>>> The DSU cluster supports blocks that are called complexes
>>> which contain up to two cores of the same type and some shared logic,
>>> which sharing some logic between the cores can make a complex area efficient.
>>Given the complex shares things like the SVE units (cortex a510)...
>>Why not handle this as SMT?
>SMT should share all cache levels. but complexs only share L2(and L3)
>cache here.
>>Seems like a blurred boundary between separate cores and SMT threads.
>>I think we need to express and potentially take advantage of knowledge
>>about what logic is being shared.
>Logic such as a Vector Processing Unit, L2 Translation Lookaside Buffer
>(TLB) ... are shared, I believe this will improve efficiency even if
>only L2 cache is shared.
>>> Complex also can be considered as a shared cache group smaller
>>> than cluster.
>>> This patch adds complex level for complexs by parsing cache topology
>>> form DT. It will directly benefit a lot of workload which loves more
>>> resources such as memory bandwidth, caches.
>>> Note this patch only handle the DT case.
>>> V2:
>>> fix commit log and loop more
>>> wangqing (2):
>>>   arch_topology: support for describing cache topology from DT
>>>   arm64: Add complex scheduler level for arm64
>>>  arch/arm64/Kconfig            | 13 ++++++++++
>>>  arch/arm64/kernel/smp.c       | 48 ++++++++++++++++++++++++++++++++++-
>>>  drivers/base/arch_topology.c  | 47 +++++++++++++++++++++++++++++++++-
>>>  include/linux/arch_topology.h |  3 +++
>>>  4 files changed, 109 insertions(+), 2 deletions(-)