[vbox-dev] NAT/slirp low outbound speed from guest's to remotehosts..

Frank Mehnert Frank.Mehnert at Sun.COM
Thu Apr 10 07:58:31 GMT 2008


On Thursday 10 April 2008, Jakob Simon-Gaarde wrote:
> Info service (svn revision 7848): I saw there had been changed made on
> slirp and NAT - so I hurried to test if the outbound NAT-problem was fixed:
> unfortunately not :(

Thanks for the report but this was to be expected as the change was related
to DHCP only.

Which guest are you using? Which host machine are you using? Do you have
VT-x enabled (make sure you have not). Do you have USB enabled? Try
switching this off at it costs performance as well.

Furthermore, you could also build a profile build. Edit the env.sh file
manually and replace BUILD_TYPE="release" by BUILD_TYPE="profile".
Recompile (there will be a new directory out/*/profile/... .

When you start the GUI you will note a new menu entry 'Debug' which contains
the entry 'Statistics...'. Open this window and you will see a bunch of
counters. Go to Devices/PCNet0. Then Increase the update interval from 0s to
1s. Re-arrange the columns with the mouse, move the dInt (which is IMHO the
most important column) more to the left. Then start your networking benchmark.

During boot you might experience some delays resulting from initializing the
counters. No worry about that.

During the benchmark have a look at the UpdateIRQ rate and updates in the
XmitFlushIRQ array. The latter should show frequent changes in all members.
The more changes in 12-16 the better (that means that bunches of packets
are sent). Perhaps you will only see updates for XmitFlushIrq=1 ...

Kind regards,

Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/
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