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andrewjhenderson · Posted: Mon Dec 08, 2008 7:07 am Post subject: Answering my own post

You have MQ v6, WMB 6, and the largest Solaris 10 box that an architect could spec ( 32 processors and a zillion GB).

You deploy a compute intensive message flow with a reasonable number of additional threads ( say 20 for fun ).

Your expectation ( based purely on your life to date, without reading all the Guides to Multi-threading on sun.com that you no doubt should have) is that you load this thing up with messages of a reasonable size and the cpu on which it runs will get very busy , so that when you run mpstat, one cpu will say :

CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl
0 118 0 2610 404 210 128 5 22 12548 1 22765 90 10 0 0

( or something similar but basically plenty of usr activity and 0 idl).

Having achieved max throughput on a single processor, you could then add a second execution group to load a second processor.

In this case, in fact mpstat says that eveything is fine , thanks, no cpu is particularly busy but they are all doing something.

However you then run ps auxww and you get

PID %CPU %MEM SZ RSS TT S START TIME COMMAND
24957 23.9 1.81 45521181848 ? O Dec 06 65:11 DataFlowEngine

23.9 % of the cpu on your 32 processor machine is in use!

Fantastic, you bought this huge box, and you can use it 1/4 of it with your single message flow with extra threads. ( like a virus!!).

Well in some ways that is good because it means there is transparent scaling for multi-threading process across multi-processors simultaneously ( see I did read sun.com).

However if you have been working in an MB world for a while, and assuming that an execution group process maps to a single processor at any one time ( and naturally governs the amount of resource you can soak up ), it is something to be aware of.

And I cant see anything about it in Solaris performance reports for MB, or in Tim Dunn's stuff about performance.

Is it just me? Or did everything change and I didnt notice?
Or does it just apply to Solaris 10?

I will now select an appropriate emoticon :