From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Avi Kivity <avi@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Marcelo Tosatti <mtosatti@redhat.com>,
Ingo Molnar <mingo@redhat.com>, Rik van Riel <riel@redhat.com>,
S390 <linux-s390@vger.kernel.org>,
Carsten Otte <cotte@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>,
Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
Alexander Graf <agraf@suse.de>, Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler
Date: Thu, 12 Jul 2012 21:24:10 +1000 [thread overview]
Message-ID: <1342092250.15597.1.camel@pasglop> (raw)
In-Reply-To: <4FFE86EC.7090001@redhat.com>
On Thu, 2012-07-12 at 11:12 +0300, Avi Kivity wrote:
> On 07/12/2012 05:17 AM, Benjamin Herrenschmidt wrote:
> >> ARM doesn't have an instruction for cpu_relax(), so it can't intercept
> >> it. Given ppc's dislike of overcommit, and the way it implements
> >> cpu_relax() by adjusting hw thread priority, I'm guessing it doesn't
> >> intercept those either, but I'm copying the ppc people in case I'm
> >> wrong. So it's s390 and x86.
> >
> > No but our spinlocks call __spin_yield() (or __rw_yield) which does
> > some paravirt tricks already.
> >
> > We check if the holder is currently running, and if not, we call the
> > H_CONFER hypercall which can be used to "give" our time slice to the
> > holder.
> >
> > Our implementation of H_CONFER in KVM is currently a nop though.
>
> Okay, so you can join the party. See yield_to() and kvm_vcpu_on_spin().
Thanks ! I'll have a look eventually :-)
Cheers,
Ben.
next prev parent reply other threads:[~2012-07-12 11:26 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
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 [this message]
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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