[Lustre-devel] Lustre RPC visualization

Michael Kluge Michael.Kluge at tu-dresden.de
Mon May 3 12:32:12 PDT 2010

Hi WangDi,

>> OK, so logically the "Completed RPC" on the client side is supposed to
>> show up after the server has written his "Handled RPC" to its log (if
>> clocks are snyc'ed perfectly).
> Yes.


>> One more question: RPC 1334380768266400 (in the log WangDi sent me)
>> has on the client side only a "Sending RPC" message, thus missing the
>> "Completed RPC". The server has all three (received,start work, done
>> work). Has this RPC vanished on the way back to the client? There is
>> no further indication what happend. The last timestamp in the client
>> log is:
>> 1272565368.228628
>> and the server says it finished the processing of the request at:
>> 1272565281.379471
>> So the client log has been recorded long enough to contain the
>> "Completed RPC" message for this RPC if it arrived ever ...
> Logically, yes. But in some cases, some debug logs might be abandoned
> for some reasons(actually, it happens not rarely), and probably you need
> maintain an average time from server "Handled RPC" to client "Completed
> RPC", then you just guess the client "Completed RPC" time in this case.

Oh my gosh ;) I don't want to start speculations about the helpfulness 
of incomplete debug logs. Anyway, what can get lost? Any kind of message 
on the servers and clients?  I think I'd like to know what cases have to 
be handled while I try to track individual RPC's on their way.

Regards, Michael

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