Xen I/O performance

[Matthias Scheler <tron%zhadum.org.uk@localhost>]

        Hello,

in the past NetBSD Xen was often blamed to cause a massive loss of
I/O performance on the dom0 compared to a machine not using Xen.
In my attempt to evaluate NetBSD Xen for use on my new server at
home I've run two benchmarks:

1.) Extracting all the NetBSD 4.0 release source sets (located on a
    tmpfs) to at the same empty local filesystem using "tar"

2.) Copying 32GB from "/dev/zero" to a file on the same non-empty
    filesystem using "dd".

The machine used for the test is a Xeon 3040 (Core 2 Duo architecture,
1.87GHz, two cores) with 5GB memory and a single 160GB SATA harddisks.
I've used the 4.99.63 NetBSD-amd64 GENERIC and XEN3_DOM0 kernels. The
amd64 kernel could use two CPU cores and 5GB memory, the Xen kernel
only one CPU core and 3.5GB memory.

Here are the results:

Kernel          "tar" (time in minutes)         "dd" (throughput in bytes/sec)
GENERIC         4:19.31                         46391830
XEN3_DOM0       3:59.20                         47161618

I'm impressed. The Xen kernel did much better than I expected.
Congratulations to Manuel for with excellent work.

        Kind regards

-- 
Matthias Scheler                                  http://zhadum.org.uk/