Re: The problems for the rootless subhurd

[olafBuddenhagen]

Hi,

On Sun, Apr 26, 2009 at 10:01:56PM +0100, Da Zheng wrote:

> I logged all RPCs and tried to analyze them. (antrik, I was wrong.
> There  aren't 100, 000 RPCs. The number of RPCs to the Mach during the
> subhurd  booting is about 20,000 - 60,000). I found something
> abnormal, but I am not sure if it should be considered  as errors.

Yeah, while rpctracing something else, I was also surprised about the
high number of failing RPCs -- this seems to be quite common throughout
the Hurd.

Note that such errors are not necessary bugs. As long as the error
return is handled appropriately, the code can be still perfectly
functional.

It would be an interesting task though to investigate such failing RPCs,
and see where they come from. Some of these might indeed indicate
non-obvious bugs, that cause various kinds of problems. Also, there
might be some room for optimization: if the caller checks for certain
parameters that will obviously cause an RPC to fail up front, it would
avoid the unnecessary roundtrip...

Anyways, while this is an interesting project (I wonder whether it could
be turned into a GSoC task for next year...), it is not likely to be
related to the subhurd problems...

My idea about the tracing was to compare the results of successful vs.
failing runs, trying to find some differences, like different order of
certain RPCs etc... But that's probably not realistic to do for traces
with 20000-60000 calls :-(

-antrik-