On Thu, Sep 22, 2022 at 10:17 AM Peter Zijlstra peterz@infradead.org wrote:
On Wed, Sep 21, 2022 at 09:48:13PM +0200, Borislav Petkov wrote:
On Wed, Sep 21, 2022 at 05:00:35PM +0200, Peter Zijlstra wrote:
On Wed, Sep 21, 2022 at 12:06:38PM +0530, K Prateek Nayak wrote:
Processors based on the Zen microarchitecture support IOPORT based deeper C-states.
I've just gotta ask; why the heck are you using IO port based idle states in 2022 ?!?! You have have MWAIT, right?
They have both. And both is Intel technology. And as I'm sure you know AMD can't do their own thing - they kinda have to follow Intel. Unfortunately.
Are you saying modern Intel chipsets don't do IO-based C-states anymore?
I've no idea what they do, but Linux exclusively uses MWAIT on Intel as per intel_idle.c.
Well, it can be forced to use ACPI idle instead.
MWAIT also cuts down on IPIs because it wakes from the TIF write.
Right.