Re: [PATCH v3 6/7] x86/smpboot: introduce per-cpu variable for HT siblings

From: Subhra Mazumdar
Date: Thu Jun 27 2019 - 21:12:24 EST



On 6/26/19 11:54 PM, Thomas Gleixner wrote:
On Thu, 27 Jun 2019, Thomas Gleixner wrote:

On Wed, 26 Jun 2019, subhra mazumdar wrote:

Introduce a per-cpu variable to keep the number of HT siblings of a cpu.
This will be used for quick lookup in select_idle_cpu to determine the
limits of search.
Why? The number of siblings is constant at least today unless you play
silly cpu hotplug games. A bit more justification for adding yet another
random storage would be appreciated.

This patch does it only for x86.
# grep 'This patch' Documentation/process/submitting-patches.rst

IOW, we all know already that this is a patch and from the subject prefix
and the diffstat it's pretty obvious that this is x86 only.

So instead of documenting the obvious, please add proper context to justify
the change.
Aside of that the right ordering is to introduce the default fallback in a
separate patch, which explains the reasoning and then in the next one add
the x86 optimized version.
OK. I will also add the extra optimization for other architectures.

Thanks,
Subhra

Thanks,

tglx