From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Rik van Riel <riel@redhat.com>,
Srikar <srikar@linux.vnet.ibm.com>,
S390 <linux-s390@vger.kernel.org>,
Carsten Otte <cotte@de.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
KVM <kvm@vger.kernel.org>, chegu vinod <chegu_vinod@hp.com>,
"Andrew M. Theurer" <habanero@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>, X86 <x86@kernel.org>,
Gleb Natapov <gleb@redhat.com>,
linux390@de.ibm.com,
Srivatsa Vaddagiri <srivatsa.vaddagiri@gmail.com>,
Joerg Roedel <joerg.roedel@amd.com>
Subject: Re: [PATCH RFC V5 3/3] kvm: Choose better candidate for directed yield
Date: Wed, 18 Jul 2012 20:09:04 +0530 [thread overview]
Message-ID: <5006CA88.8040906@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120718133800.5321.51446.sendpatchset@codeblue.in.ibm.com>
On 07/18/2012 07:08 PM, Raghavendra K T wrote:
> From: Raghavendra K T<raghavendra.kt@linux.vnet.ibm.com>
> +bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
> +{
> + bool eligible;
> +
> + eligible = !vcpu->spin_loop.in_spin_loop ||
> + (vcpu->spin_loop.in_spin_loop&&
> + vcpu->spin_loop.dy_eligible);
> +
> + if (vcpu->spin_loop.in_spin_loop)
> + vcpu->spin_loop.dy_eligible = !vcpu->spin_loop.dy_eligible;
> +
> + return eligible;
> +}
I should have added a comment like:
Since algorithm is based on heuristics, accessing another vcpu data
without locking does not harm. It may result in trying to yield to same
VCPU, fail and continue with next and so on.
next prev parent reply other threads:[~2012-07-18 14:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-18 13:37 [PATCH RFC V5 0/3] kvm: Improving directed yield in PLE handler Raghavendra K T
2012-07-18 13:37 ` [PATCH RFC V5 1/3] kvm/config: Add config to support ple or cpu relax optimzation Raghavendra K T
2012-07-18 13:37 ` [PATCH RFC V5 2/3] kvm: Note down when cpu relax intercepted or pause loop exited Raghavendra K T
2012-07-18 13:38 ` [PATCH RFC V5 3/3] kvm: Choose better candidate for directed yield Raghavendra K T
2012-07-18 14:39 ` Raghavendra K T [this message]
2012-07-19 9:47 ` [RESEND PATCH " Raghavendra K T
2012-07-20 17:36 ` [PATCH RFC V5 0/3] kvm: Improving directed yield in PLE handler Marcelo Tosatti
2012-07-22 12:34 ` Raghavendra K T
2012-07-22 12:43 ` Avi Kivity
2012-07-23 7:35 ` Christian Borntraeger
2012-07-22 17:58 ` Rik van Riel
2012-07-23 10:03 ` Avi Kivity
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