From: Michael Mueller <mimu@linux.vnet.ibm.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Gleb Natapov <gleb@kernel.org>, KVM <kvm@vger.kernel.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Cornelia Huck <cornelia.huck@de.ibm.com>,
Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Subject: Re: [PATCH/RFC 2/3] s390/kvm: Platform specific kvm_arch_vcpu_dont_yield
Date: Mon, 24 Feb 2014 15:22:05 +0100 [thread overview]
Message-ID: <20140224152205.0e1be9f6@bee> (raw)
In-Reply-To: <52FDE813.5050809@de.ibm.com>
On Fri, 14 Feb 2014 10:55:31 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> On 14/02/14 00:32, Paolo Bonzini wrote:
> > Il 13/02/2014 23:54, Christian Borntraeger ha scritto:
> >> We had several variants but in the end we tried to come up with a patch that does not
> >> influence other architectures. Your proposal would certainly be fine for s390,
> >> but what impact does it have on x86, arm, arm64? Will it cause performance regressions?
> >
> > It may also have the same advantages you got on s390.
> >
> >> So I think that the patch as is is probably the safest choice until we have some
> >> data from x86, arm, arm64, no?
> >
> > No, using an existing API is always better than inventing a new one.
>
> OK.
> Michael can you rework the series to simply use
> " if (waitqueue_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu)" in kvm_vcpu_on_spin
>
> and make kvm_arch_vcpu_runnable kvm_cpu_has_interrupt(vcpu) in s390 code?
> That should be equivalent for s390 with even simpler code.
> It might also help x86 and others.
Ok, I will adapt the patch accordingly...
>
>
> > If you post the new patch series, and describe the benchmark you were using, we can reproduce
> > it on x86.
>
> The benchmark was some workload doing lots of semaphore up/down with hundreds
> of processes. Will see if I can come up with a minimal test.
>
>
>
>
next prev parent reply other threads:[~2014-02-24 14:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-11 11:45 [PATCH/RFC 0/3] KVM: yield heuristic improvements Christian Borntraeger
2014-02-11 11:45 ` [PATCH/RFC 1/3] kvm: Introduction of kvm_arch_vcpu_dont_yield() Christian Borntraeger
2014-02-11 11:45 ` [PATCH/RFC 2/3] s390/kvm: Platform specific kvm_arch_vcpu_dont_yield Christian Borntraeger
2014-02-13 22:37 ` Paolo Bonzini
2014-02-13 22:54 ` Christian Borntraeger
2014-02-13 23:32 ` Paolo Bonzini
2014-02-14 9:55 ` Christian Borntraeger
2014-02-14 9:56 ` Paolo Bonzini
2014-02-24 14:22 ` Michael Mueller [this message]
2014-02-11 11:45 ` [PATCH/RFC 3/3] s390/kvm: Set preempted flag during vcpu wakeup and interrupt delivery Christian Borntraeger
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