[Pvfs2-developers] epoll fun

[Sam Lang]

On Oct 4, 2007, at 4:42 PM, Sam Lang wrote:

>
> On Oct 4, 2007, at 3:45 PM, Pete Wyckoff wrote:
>
>> slang at mcs.anl.gov wrote on Thu, 04 Oct 2007 15:21 -0500:
>>> I'm in the process of getting a trace and dump from the same server
>>> during the same runs.
>>
>> Good, will be interesting too see tcpdump + strace.
>
> Pete,
>
> Here's a trace and dump from the same set of runs.
>
> http://www.mcs.anl.gov/~slang/epoll-trace.out [370MB]
> http://www.mcs.anl.gov/~slang/server-packets.dump [180MB]
>
> Again, the trace isn't from strace, I'm tracing the epoll calls  
> manually.
>

Damnit, I forgot to recompile the servers.  These results are with  
poll.  The slowdown still exists for these runs though.
-sam

> -sam
>
>
>>   Although I
>> worry we might not learn anything new.
>>
>>> In the meantime, I attached two "zoomed" plots of the last one I
>>> sent, with ranges set to 5000-5200 secs and 5000-6000 secs,
>>> respectively.  I thought they were interesting, both for the  
>>> behavior
>>> that epoll_wait exhibits during operations over the VFS, and just  
>>> for
>>> the patterns they show at a scale of 100s of seconds (it almost  
>>> looks
>>> like a seirpinski triangle).  Not that it sheds much light on the
>>> problem.
>>
>> Pretty.  Maybe there's a category for Most Attractive Unexplained
>> Distributed System Art in the state fair this year.
>>
>> Would the pending request ID stuff with slog etc be useful in
>> tracking individual operations?
>>
>> 		-- Pete
>>
>