Subject: Re: rpc xid randomness
To: Jun-ichiro itojun Hagino <>
From: Brett Lymn <>
List: tech-security
Date: 09/09/2003 12:17:15
On Tue, Sep 09, 2003 at 10:51:59AM +0900, Jun-ichiro itojun Hagino wrote:
> 	could anyone with lmbench do lat_rpc with the old code?

I cannot seem to reliably get lat_rpc to run - sometimes I get rpc
timeouts but the couple of times it has worked I get 61 microseconds
for RPC/tcp and 57 microseconds for RPC/udp... or numbers around that
mark.  This is running on a laptop with a 1Ghz PIII, 256Mb RAM - I was
running X at the time I ran the benchmark.
> 	the numbers i've posted (hoge.c) could be misleading, as (1) it only
> 	measures the algorithm itself, not the impact to RPC code as a
> whole,

True - that is why I was careful not to overreact to your timings.
Can you post the results of lat_rpc for comparison?

> 	(2) it runs on userland so kernel-userland overhead like gettimeofday()
> 	call which makes it inaccurate.

True but that overhead is relatively constant in your before/after
case so the perturbation in your measurement should not be that high,
certainly not by 3 orders of magnitude which is what your numbers were

Brett Lymn