Re: [PATCH 3/3] KVM: s390: clear kicked_mask if not idle after set

From: Christian Borntraeger
Date: Wed Oct 20 2021 - 06:52:39 EST




Am 20.10.21 um 12:45 schrieb Halil Pasic:
On Wed, 20 Oct 2021 12:31:19 +0200
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:

Before releasing something like this, where none of us is sure if
it really saves cpu cost, I'd prefer to run some measurement with
the whole kicked_mask logic removed and to compare the number of
vcpu wake ups with the number of interrupts to be processed by
the gib alert mechanism in a slightly over committed host while
driving with Matthews test load.

But I think patch 1 and 2 can go immediately as they measurably or
testable fix things. Correct?

I think so as well. And if patch 3 is going to be dropped, I would
really like to keep the unconditional clear in kvm_arch_vcpu_runnable(),
as my analysis in the discussion points out: I think it can save us
form trouble this patch is trying to address.

Yes, lets keep patch 1 and 2 as us and let us look deeper into this patch.
I will apply and queue 1 and 2 soon.