From: Davidlohr Bueso <dave@gnu.org>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, KVM <kvm@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KVM: VMX: invalidate vpid for invlpg instruction
Date: Wed, 05 Sep 2012 23:54:21 +0200 [thread overview]
Message-ID: <1346882061.6304.17.camel@offbook> (raw)
In-Reply-To: <50447442.2050307@redhat.com>
On Mon, 2012-09-03 at 12:11 +0300, Avi Kivity wrote:
> On 09/03/2012 02:27 AM, Davidlohr Bueso wrote:
> > On Fri, 2012-08-31 at 14:37 -0300, Marcelo Tosatti wrote:
> >> On Fri, Aug 31, 2012 at 06:10:48PM +0200, Davidlohr Bueso wrote:
> >> > For processors that support VPIDs we should invalidate the page table entry
> >> > specified by the lineal address. For this purpose add support for individual
> >> > address invalidations.
> >>
> >> Not necessary - a single context invalidation is performed through
> >> KVM_REQ_TLB_FLUSH.
> >
> > Since vpid_sync_context() supports both single and all-context vpid
> > invalidations, wouldn't it make sense to also add individual address
> > ones as well, supporting further granularity?
>
> It might. Do you have benchmarks supporting this?
>
I ran two benchmarks: Java Dacapo[1] Sunflow (renders a set of images
using ray tracing) and a vanilla 3.2 kernel build (with 1 job and -j8).
The host configuration is an Intel i7-2635QM (4 cores + HT) with 4Gb RAM
running Linus's latest and only running standard system daemons. For KVM
I disabled EPT.
The guest configuration is a 64bit 4 core 4Gb RAM, running Linux 3.2
(debian) and only running the benchmark.
All results represent the mean of 5 runs, with time(1).
Dacapo without individual addr invvpid:
real 1m25.406s
user 4m59.315s
sys 1m25.406s
Dacapo with individual addr invvpid:
real 1m4.421s
user 3m47.150s
sys 0m1.592s
--
vanilla kernel build without individual addr invvpid:
real 16m42.571s
user 13m28.975s
sys 2m54.487s
vanilla kernel build with individual addr invvpid:
real 15m45.789s
user 12m25.691s
sys 2m44.806s
--
vanilla kernel build (-j8) without individual addr invvpid:
real 10m32.276s
user 33m47.687s
sys 5m37.725s
vanilla kernel build (-j8) with individual addr invvpid:
real 8m29.789s
user 28m12.850s
sys 4m34.353s
In all cases using individual address invalidation outperforms single
context ones regarding wall time. Comments?
[1] http://dacapobench.org/
Thanks,
Davidlohr
next prev parent reply other threads:[~2012-09-05 21:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-31 16:10 [PATCH] KVM: VMX: invalidate vpid for invlpg instruction Davidlohr Bueso
2012-08-31 17:37 ` Marcelo Tosatti
2012-09-02 23:27 ` Davidlohr Bueso
2012-09-03 9:11 ` Avi Kivity
2012-09-05 21:54 ` Davidlohr Bueso [this message]
2012-09-06 8:05 ` Avi Kivity
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