[Lustre-devel] Lustre RPC visualization

Andrew Uselton acuselton at lbl.gov
Sun May 16 20:24:55 PDT 2010

I think this work is very interesting.  Will anyone be at CUG 2010 next week
to discuss?

2010/5/16 Michael Kluge <Michael.Kluge at tu-dresden.de>

> Hi WangDi,
> the first version works. Screenshot is attached. I have a couple of counter
> realized: RPC's in flight and RPC's completed in total on the client, RPC's
> enqueued, RPC's in processing and RPC'c completed in total on the server.
> All these counter can be broken down by the type of RPC (op code). The
> picture has not yet the lines that show each single RPC, I still have to do
> counter like "avg. time to complete an RPC over the last second" and there
> are some more TODO's. Like the timer synchronization. (In the screenshot the
> first and the last counter show total values while the one in the middle
> shows a rate.)
> What I like to have is a complete set of traces from a small cluster (<100
> nodes) including the servers. Would that be possible?
> Is one of you in Hamburg May, 31-June, 3 for ISC'2010? I'll be there and
> like to talk about what would be useful for the next steps.
> Regards, Michael
> Am 03.05.2010 21:52, schrieb di.wang:
>> Michael Kluge wrote:
>>  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.
>> Any records can get lost here. Unfortunately, there are not any messages
>> indicate the missing happened. :(
>> (Usually, I would check the time stamp in the log, i.e. no records for a
>> "long" time, for example several seconds, but this is not the accurate
>> way).
>> I guess you can just ignore these uncompleted records in your first
>> step? Let's see how these incomplete log will
>> impact the profiling result, then we will decide how to deal with this?
>> Thanks
>> Wangdi
>>> Regards, Michael
>>> _______________________________________________
>>> Lustre-devel mailing list
>>> Lustre-devel at lists.lustre.org
>>> http://lists.lustre.org/mailman/listinfo/lustre-devel
> --
> Michael Kluge, M.Sc.
> Technische Universität Dresden
> Center for Information Services and
> High Performance Computing (ZIH)
> D-01062 Dresden
> Germany
> Contact:
> Willersbau, Room WIL A 208
> Phone:  (+49) 351 463-34217
> Fax:    (+49) 351 463-37773
> e-mail: michael.kluge at tu-dresden.de
> WWW:    http://www.tu-dresden.de/zih
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