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

Re: [Xen-devel] write_tsc in a PV domain?

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 31 Aug 2009 20:06:02 +0100
Cc: "Xen-Devel \(E-mail\)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Mon, 31 Aug 2009 12:06:36 -0700
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
Thread-index: AcoqZo+1DdtLBxzcQK24QKYKl17krwAB4VDL
Thread-topic: [Xen-devel] write_tsc in a PV domain?

On 31/08/2009 19:11, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> I have yet to get a measurement of either syscall that
> is better than 2.5x WORSE than emulating rdtsc. On
> my dual-core Conroe (Intel E6850) with 64-bit Xen and
> 32-bit dom0, I get approximately:
> 
> rdtsc native: 22ns
> softtsc (rdtsc emulated): 360ns

Trap-and-emulate in 360ns seems astoundingly good. Perhaps too good to be
true?

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

Follow-Ups:
- RE: [Xen-devel] write_tsc in a PV domain?
  - From: Dan Magenheimer

References:
- RE: [Xen-devel] write_tsc in a PV domain?
  - From: Dan Magenheimer

Prev by Date: [Xen-devel] Trace Disk I/O per guest domain!
Next by Date: Re: [Xen-devel] Trace Disk I/O per guest domain!
Previous by thread: RE: [Xen-devel] write_tsc in a PV domain?
Next by thread: RE: [Xen-devel] write_tsc in a PV domain?
Index(es):
- Date
- Thread

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