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Re: [Xen-devel] [PATCH RFC v2 0/4] HVM x86 deprivileged mode operations
- To: David Vrabel <david.vrabel@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Ben Catterall <Ben.Catterall@xxxxxxxxxx>
- Date: Mon, 7 Sep 2015 11:50:55 +0100
- Cc: keir@xxxxxxx, jbeulich@xxxxxxxx, george.dunlap@xxxxxxxxxxxxx, andrew.cooper3@xxxxxxxxxx, tim@xxxxxxx, Aravind.Gopalakrishnan@xxxxxxx, suravee.suthikulpanit@xxxxxxx, boris.ostrovsky@xxxxxxxxxx, ian.campbell@xxxxxxxxxx
- Delivery-date: Mon, 07 Sep 2015 10:51:03 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 03/09/15 17:15, David Vrabel wrote:
On 03/09/15 17:01, Ben Catterall wrote:
Intel Intel 2.2GHz Xeon E5-2407 0 processor:
--------------------------------------------
1.55e-06 seconds was the average time for performing the write without the
deprivileged code running.
5.75e-06 seconds was the average time for performing the write with the
deprivileged code running.
So approximately 351% overhead
AMD Opteron 2376:
-----------------
1.74e-06 seconds was the average time for performing the write without the
deprivileged code running.
3.10e-06 seconds was the average time for performing the write with an entry and
exit from deprvileged mode.
So approximately 178% overhead.
How does this compare to the overhead of passing the I/O through to qemu?
So, passing this portio op through to QEMU takes roughly 20e-6 seconds.
However, I don't know if the emulator would have gone and prodded a
physical port as port of that which could skew the result. I'll look
into this and get back if I find anything to clarify this.
Ben
David
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