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

[ns] Validation on intel linux



Hi,

I normally do my ns work on solaris boxes, but we recently got some 600MHz
PCs in and I wanted to see how much faster than our (relatively old)
solaris box they are.

I compiled ns-2.1b6 on the system without any difficulty. I then ran the
validation tests and found, to my surprise, that many of them failed. I
had a look on the website and found Sally Floyds mail that briefly
describes the reasons why results differ on intel linux platforms from
those obtained on platforms that use IEEE floating point arithmetic.

I was going to suggest putting the output of 'make test' somewhere on the
website, so that people would know if their ns distribution is doing the
same things as it does on other peoples linux boxes. This got me to
thinking about the tests, and I couldn't think of many reasons why the
tests would differ between different modern versions of linux.
Consequently, it may be useful to put such output on the website to make
people more confident that their version of ns is working in the same way
as other peoples, but I think that nearly everybody who can run the binary
on modern linux systems should get the same results.

Here, we think in terms of using linux intel (lintel?) boxes for any
heavy-duty work in the future, and I'm sure many organisations think like
this. Hence, I think it's important to have a set of tests that work on
such boxes. Perhaps it would be a good idea to distribute the test output
as run on a lintel box with the distribution with the caveat that some of
the tests have not been checked against the reference output. Over time
people, I guess, would check results of tests run on the lintel boxes
against the reference tests and (hopefully) ensure that the differences
are only due to floating point operations. Such tests would also be useful
for ensuring consistent behaviour (even if it's not certain to be
accurate) - if the behaviour changes, then it could point to a bug -
across different ns distributions (ns-2.1b6, ns-2.1b7 etc).

Regards,
Sean.

-----
Sean Murphy,			Email: [email protected]
Teltec Ireland,			Phone: +353-1-7045080
DCU, Dublin 9,			Fax:   +353-1-7045092
Ireland.