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From: Sean Christopherson <seanjc@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: lirongqing@baidu.com, pbonzini@redhat.com, wanpengli@tencent.com,
	vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, x86@kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH][v2] x86/kvm: Don't check vCPU preempted if vCPU has dedicated pCPU and non-trap HLT
Date: Thu, 6 Apr 2023 09:08:33 -0700	[thread overview]
Message-ID: <ZC7ugeST1OOdNANg@google.com> (raw)
In-Reply-To: <20230406095711.GH386572@hirez.programming.kicks-ass.net>

On Thu, Apr 06, 2023, Peter Zijlstra wrote:
> On Thu, Apr 06, 2023 at 03:33:13PM +0800, lirongqing@baidu.com wrote:
> > From: Li RongQing <lirongqing@baidu.com>
> > 
> > Check whether vCPU is preempted or not only when HLT is trapped or
> > there is not realtime hint. In other words, it is unnecessary to check
> > preemption when vCPU has realtime hint (which means vCPU has dedicated
> > pCP) and has not PV_UNHALT (which means unintercepted HLT), because
> > vCPU should not to be marked as preempted in this setup.
> 
> To what benefit?
> 
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> > ---
> > diff with v1: rewrite changelog and indentation

This also fails to mention my objection to querying PV_UNHALT[*].  When I said
"this needs Paolo's attention no matter what", I did not mean "post a v2 and hope
Paolo applies it", I meant we need Paolo (and others) to weigh in on the ongoing
discussion.

[*] https://lore.kernel.org/all/ZBEOK6ws9wGqof3O@google.com

  reply	other threads:[~2023-04-06 16:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-06  7:33 [PATCH][v2] x86/kvm: Don't check vCPU preempted if vCPU has dedicated pCPU and non-trap HLT lirongqing
2023-04-06  9:57 ` Peter Zijlstra
2023-04-06 16:08   ` Sean Christopherson [this message]
2023-04-06 16:49     ` Paolo Bonzini

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