From: Avi Kivity <avi@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>,
mingo@elte.hu, jeremy@goop.org, mtosatti@redhat.com,
kvm@vger.kernel.org, x86@kernel.org, vatsa@linux.vnet.ibm.com,
linux-kernel@vger.kernel.org, hpa@zytor.com
Subject: Re: [RFC PATCH v1 3/5] KVM: Add paravirt kvm_flush_tlb_others
Date: Tue, 01 May 2012 18:33:08 +0300 [thread overview]
Message-ID: <4FA00234.1020006@redhat.com> (raw)
In-Reply-To: <1335885103.13683.147.camel@twins>
On 05/01/2012 06:11 PM, Peter Zijlstra wrote:
> On Tue, 2012-05-01 at 15:12 +0300, Avi Kivity wrote:
> > We're now moving the freeing of kvm shadow page tables from using rcu to
> > using an irq-protected scheme like gup_fast(), because of the
> > performance differences. We didn't track it down but I expect the cause
> > is less reuse of cache-hot pages.
>
> It would be good to understand these things.. just doing things because
> tends to come back and bite you :-)
Agree. Anyway that was only part of the motivation, the other part was
establishing a bound on the number of pages under deferred freeing.
> If its cache behaviour you should be able to clearly see that using perf
> stat.
It's hard to see it clearly because the changes are in the order of 1-2%
in a very noisy benchmark.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-05-01 15:33 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 16:23 [RFC PATCH v1 0/5] KVM paravirt remote flush tlb Nikunj A. Dadhania
2012-04-27 16:23 ` [RFC PATCH v1 1/5] KVM Guest: Add VCPU running/pre-empted state for guest Nikunj A. Dadhania
2012-05-01 1:03 ` Raghavendra K T
2012-05-01 3:25 ` Nikunj A Dadhania
2012-04-27 16:23 ` [RFC PATCH v1 2/5] KVM-HV: " Nikunj A. Dadhania
2012-04-27 16:24 ` [RFC PATCH v1 3/5] KVM: Add paravirt kvm_flush_tlb_others Nikunj A. Dadhania
2012-04-29 12:23 ` Avi Kivity
2012-05-01 3:34 ` Nikunj A Dadhania
2012-05-01 9:39 ` Peter Zijlstra
2012-05-01 10:47 ` Avi Kivity
2012-05-01 10:57 ` Peter Zijlstra
2012-05-01 10:59 ` Peter Zijlstra
2012-05-01 22:49 ` Jeremy Fitzhardinge
2012-05-03 14:09 ` Stefano Stabellini
2012-05-01 12:12 ` Avi Kivity
2012-05-01 14:59 ` Peter Zijlstra
2012-05-01 15:31 ` Avi Kivity
2012-05-01 15:36 ` Peter Zijlstra
2012-05-01 15:39 ` Avi Kivity
2012-05-01 15:42 ` Peter Zijlstra
2012-05-01 15:11 ` Peter Zijlstra
2012-05-01 15:33 ` Avi Kivity [this message]
2012-05-01 15:14 ` Peter Zijlstra
2012-05-01 15:36 ` Avi Kivity
2012-05-01 16:16 ` Peter Zijlstra
2012-05-01 16:43 ` Paul E. McKenney
2012-05-01 16:18 ` Peter Zijlstra
2012-05-01 16:20 ` Peter Zijlstra
2012-05-02 8:51 ` Nikunj A Dadhania
2012-05-02 10:20 ` Peter Zijlstra
2012-05-02 13:53 ` Nikunj A Dadhania
2012-05-04 4:32 ` Nikunj A Dadhania
2012-05-04 11:44 ` Srivatsa Vaddagiri
2012-05-07 3:10 ` Nikunj A Dadhania
2012-04-27 16:26 ` [RFC PATCH v1 4/5] KVM: get kvm_kick_vcpu out for pv_flush Nikunj A. Dadhania
2012-04-27 16:27 ` [RFC PATCH v1 5/5] KVM: Introduce PV kick in flush tlb Nikunj A. Dadhania
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