From: Rik van Riel <riel@redhat.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Marcelo Tosatti <mtosatti@redhat.com>,
Ingo Molnar <mingo@redhat.com>, Avi Kivity <avi@redhat.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 2/2] kvm PLE handler: Choose better candidate for directed yield
Date: Mon, 09 Jul 2012 18:30:25 -0400 [thread overview]
Message-ID: <4FFB5B81.4040903@redhat.com> (raw)
In-Reply-To: <20120709062053.24030.52767.sendpatchset@codeblue>
On 07/09/2012 02:20 AM, Raghavendra K T wrote:
> +bool kvm_arch_vcpu_check_and_update_eligible(struct kvm_vcpu *vcpu)
> +{
> + bool eligible;
> +
> + eligible = !vcpu->arch.plo.pause_loop_exited ||
> + (vcpu->arch.plo.pause_loop_exited&&
> + vcpu->arch.plo.dy_eligible);
> +
> + if (vcpu->arch.plo.pause_loop_exited)
> + vcpu->arch.plo.dy_eligible = !vcpu->arch.plo.dy_eligible;
> +
> + return eligible;
> +}
This is a nice simple mechanism to skip CPUs that were
eligible last time and had pause loop exits recently.
However, it could stand some documentation. Please
add a good comment explaining how and why the algorithm
works, when arch.plo.pause_loop_exited is cleared, etc...
It would be good to make this heuristic understandable
to people who look at the code for the first time.
--
All rights reversed
next prev parent reply other threads:[~2012-07-09 22:31 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-09 6:20 [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler Raghavendra K T
2012-07-09 6:20 ` [PATCH RFC 1/2] kvm vcpu: Note down pause loop exit Raghavendra K T
2012-07-09 6:33 ` Raghavendra K T
2012-07-09 22:39 ` Rik van Riel
2012-07-10 11:22 ` Raghavendra K T
2012-07-11 8:53 ` Avi Kivity
2012-07-11 10:52 ` Raghavendra K T
2012-07-11 11:18 ` Avi Kivity
2012-07-11 11:56 ` Raghavendra K T
2012-07-11 12:41 ` Andrew Jones
2012-07-12 10:58 ` Nikunj A Dadhania
2012-07-12 11:02 ` Raghavendra K T
2012-07-09 6:20 ` [PATCH RFC 2/2] kvm PLE handler: Choose better candidate for directed yield Raghavendra K T
2012-07-09 22:30 ` Rik van Riel [this message]
2012-07-10 11:46 ` Raghavendra K T
2012-07-09 7:55 ` [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler Christian Borntraeger
2012-07-10 8:27 ` Raghavendra K T
2012-07-11 9:06 ` Avi Kivity
2012-07-11 10:17 ` Christian Borntraeger
2012-07-11 11:04 ` Avi Kivity
2012-07-11 11:16 ` Alexander Graf
2012-07-11 11:23 ` Avi Kivity
2012-07-11 11:52 ` Alexander Graf
2012-07-11 12:48 ` Avi Kivity
2012-07-12 2:19 ` Benjamin Herrenschmidt
2012-07-11 11:18 ` Christian Borntraeger
2012-07-11 11:39 ` Avi Kivity
2012-07-12 5:11 ` Raghavendra K T
2012-07-12 8:11 ` Avi Kivity
2012-07-12 8:32 ` Raghavendra K T
2012-07-12 2:17 ` Benjamin Herrenschmidt
2012-07-12 8:12 ` Avi Kivity
2012-07-12 11:24 ` Benjamin Herrenschmidt
2012-07-12 10:38 ` Nikunj A Dadhania
2012-07-11 11:51 ` Raghavendra K T
2012-07-11 11:55 ` Christian Borntraeger
2012-07-11 12:04 ` Raghavendra K T
2012-07-11 13:04 ` Raghavendra K T
2012-07-09 21:47 ` Andrew Theurer
2012-07-10 9:26 ` Raghavendra K T
2012-07-10 10:07 ` [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler : detailed result Raghavendra K T
2012-07-10 11:54 ` [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler Raghavendra K T
2012-07-10 13:27 ` Andrew Theurer
2012-07-11 9:00 ` Avi Kivity
2012-07-11 13:59 ` Raghavendra K T
2012-07-11 14:01 ` Raghavendra K T
2012-07-12 8:15 ` Avi Kivity
2012-07-12 8:25 ` Raghavendra K T
2012-07-12 12:31 ` Avi Kivity
2012-07-09 22:28 ` Rik van Riel
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