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Re: [Xen-devel] [PATCH] respin of mprotect performance patch

On Mon, 21 Jan 2008 10:41:59 -0500
Rik van Riel <riel@xxxxxxxxxx> wrote:

> I tested a quick backport of these patches to XEN 3.1.2 and
> kernel 2.6.18.
> Unfortunately, performance and scalability do not seem to
> have improved with these patches,

OK, it turned out the guys with the SAP mprotect benchmark program
made the mistake of only upgrading the dom0 kernel and not the guest.

With both dom0 and guest, mprotect performance has improved slightly
on our dual cpu, dual core (4 cores total) Intel x86-64 test system:

1        13108.77    11188.68
2        13135.63    11146.06
3        10522.82     9910.10
4         8622.47     9399.66
6         6571.49     7078.12
8         5141.23     5389.15
10        4514.37     4372.87
12        4226.79     3802.98

So we have about a 10-15% performance improvement at some numbers of
streams, and a performance decrease at some other numbers of streams.
Over-all performance impact of the patch seems to be about even :(

I wonder if this is just an artifact of the system we tested this on,
or if it can be seen across multiple systems.

Bruce, what kinds of systems have you tested the patch on and what
kind of performance numbers are you seeing?

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