Re: [PATCH 0/9] Add CPU-type to topology

From: Brice Goglin
Date: Sat Jun 29 2024 - 07:37:49 EST



Le 27/06/2024 à 15:22, Pawan Gupta a écrit :
On Thu, Jun 27, 2024 at 05:51:54AM -0700, Ricardo Neri wrote:
ARM gives userspace specific details. This makes more sense to me. Instead
of reading these details, user space would have to infer these details if
a CPU type was given in sysfs.

Having said that, Intel does have a CPUID leaf that gives the CPU type. Such
leaf also has a "Native Model ID". Exposing only the CPU type may not be
sufficient.
Do we know if there are applications that would benefit from this information?


There are HPC users who want a homogeneous set of cores, ie only P-core, or only E-core without the low power ones (because they don't want some imbalance between task speed in homogeneous parallel jobs). I've received requests from hwloc users running small parallel jobs on their desktop/laptop machines, and also from developers of big apps who want to debug on their laptop without heterogeneous cores creating imbalance that don't exist on servers.

They don't care much about the actual hardware details so far, they mostly want an ordered list of set of homogeneous cores (ordered from performance -> low-energy).

Brice