[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH 2 of 2] vpmu: Add a vpmu cpuid function

  • To: Ian Campbell <ian.campbell@xxxxxxxxxx>
  • From: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
  • Date: Fri, 20 Jan 2012 13:40:19 +0100
  • Cc: Wei Wang <wei.wang2@xxxxxxx>, Haitao Shan <haitao.shan@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir@xxxxxxx>
  • Delivery-date: Fri, 20 Jan 2012 12:40:34 +0000
  • Domainkey-signature: s=s1536a; d=ts.fujitsu.com; c=nofws; q=dns; h=X-SBRSScore:X-IronPort-AV:Received:X-IronPort-AV: Received:Received:From:To:Cc:Subject:Date:Message-ID: User-Agent:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:Content-Type; b=UMDjL0CahaIuFUlNVNEYlCn1qikg6XxlTzB62IUGvJmQjMhjodyhlVJe /OxXO5sD9zZ131d8M6ef1/f4JU+QORWCJAVQ9ZhrHHa9BLxrud10OPGx0 gIi1YNJEvljd2L08cy2C+KaTcIjFRW6mdmiVaUKHpQ2cDYx9mf/xS4iTl urCHPdXfZyzOI9/6onhASu7MifvAyL9tgu8GIcwPGQy7DOvNZ1idYIsf4 dl7fhLzXziau/V5VATASSFONagG4G;
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Hi Ian,

Am Freitag 20 Januar 2012, 10:54:44 schrieb Keir Fraser:
> On 20/01/2012 10:49, "Dietmar Hahn" <dietmar.hahn@xxxxxxxxxxxxxx> wrote:
> >> Our CPUID configuration is done per-domain, and from
> >> tools/libxc/xc_cpuid_x86.c. CPUID adjustments implemented within the
> >> hypervisor are generally not acceptable without very good reason.
> > 
> > Then a way is needed to have access to the opt_vpmu_enabled variable within
> > the
> > hypervisor from the tools to decide the enabling of the flag (is there such 
> > a
> > way?) or the mechanism with the boot variable must be changed.
> > The opt_vpmu_enabled boot variable was introduced because of a PMU problem 
> > in
> > the Nehalem cpus leading sometimes to hypervisor crashes. But with the done
> > quirk we never had a crash anymore.
> > So maybe we can always switch on the vpmu stuff in the hypervisor and add a
> > flag in the domain configuration when somebody wants to do some performance
> > tests?
> Yes!
> It's obviously an option of fairly narrow interest. If someone tries to
> enable the per-domain option on a CPU which has problems, you can fail the
> domain creation, or print a warning in the hypervisor log, or whatever. Any
> sensible option in that respect is fine by me!

What is the best solution for this?
A domain specific configuration option is needed (vpmu?) which is usable in
libxc/xc_cpuid_x86.c to select/deselect special vpmu bits in the cpuid command.
Can you point me to an proper example?


Company details: http://ts.fujitsu.com/imprint.html

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.