[Opensim-dev] Lockless Lists?

[Dr Scofield]

Christopher Yeoh wrote:
> On Mon, 24 Nov 2008 20:43:09 +0100
> "Homer Horwitz" <homerhorwitz at googlemail.com> wrote:
>> So, I'm not sure if we really should do that move. If at all, I'm for
>> a very slow move to lock-free versions from a rather stable software
>> base (which we currently don't have in trunk), so errors that are
>> introduced during that move are more easily identifiable, with much
>> testing in-between. Even then, I'm absolutely sure we will get a lot
>> of Heisenbugs in the process, which will take us weeks to find.
>>
> 
> Perhaps what is really needed here is some performance benchmarks 
> which highlight existing problems? So for individual
> changes to lockless versions we better see what improvements we'd
> get on both small and large SMP machines and whether its worth the
> increase in complexity.
> 
> I did some debugging of a deadlock a couple of weeks ago and found it
> already pretty complicated. Any suggestions on how other people
> approach these problems with OpenSim? I sprinkled lots of console
> messages around as mdb doesn't seem to work for me, but in retrospect
> it would have been really handy to have been able to just turn on
> a lock debugging flag and have debug output when locks are taken
> and released.

in theory, you can trace specific instructions with mono...in theory, because i
haven't succeeded yet in getting this really done without being drowned in
console messages (sean might have more experience with this).

i agree console messages are not really the cat's whiskers and the additional
problem with console messages is that it will change timing and might get you
nowhere...


-- 
dr dirk husemann ---- virtual worlds research ---- ibm zurich research lab
SL: dr scofield ---- drscofield at xyzzyxyzzy.net ---- http://xyzzyxyzzy.net/
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