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Date:   Wed, 22 Nov 2023 12:51:19 -0800 (PST)
From:   Christoph Lameter <cl@linux.com>
To:     Mihai Carabas <mihai.carabas@oracle.com>
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Subject: Re: [PATCH 7/7] cpuidle/poll_state: replace cpu_relax with
 smp_cond_load_relaxed
In-Reply-To: <1700488898-12431-8-git-send-email-mihai.carabas@oracle.com>
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References: <1700488898-12431-1-git-send-email-mihai.carabas@oracle.com> <1700488898-12431-8-git-send-email-mihai.carabas@oracle.com>
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On Mon, 20 Nov 2023, Mihai Carabas wrote:

> cpu_relax on ARM64 does a simple "yield". Thus we replace it with
> smp_cond_load_relaxed which basically does a "wfe".

Well it clears events first (which requires the first WFE) and then does a 
WFE waiting for any events if no events were pending.

WFE does not cause a VMEXIT? Or does the inner loop of 
smp_cond_load_relaxed now do 2x VMEXITS?

KVM ARM64 code seems to indicate that WFE causes a VMEXIT. See 
kvm_handle_wfx().