| Title: | FDDI - The Next Generation |
| Moderator: | NETCAD::STEFANI |
| Created: | Thu Apr 27 1989 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2259 |
| Total number of notes: | 8590 |
Hi there, A customer ask me a question about the performance on VAXstation 4000-90 with FDDI connected. I am not familiar with FDDI so I would like to ask anybody know that and give me a hand. The customer have two VAXstation 4000-90 and installed with FDDI controller on them. Each system has 64 M memory and it is standalone (just station). They found that everytime when they use the network, (through FDDI), for example copy files between the two machine. The CPU's usage is almost full. They use monitor system and check that it is alomst about 100%. Is it normal? Does FDDI is CUP bound? I never play with a FDDI system before, I don't wheter it is normal or not. Is there anybody knows that it is normal or not? Thanks for your help in advance. Kenneth Leung
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 820.1 | yes the CPU is busy, and that's good | MUDDY::WATERS | Wed Dec 23 1992 08:39 | 16 | |
If the network is relatively idle (the normal case), DECnet file
transfers over FDDI will saturate all but the fastest CPUs. (The same
is true for TCP/IP protocols.) If the network is quite busy, then the
transfer may slow down and some CPU time may be left over.
If you have a multiprocessor machine, moving data through the FDDI
adapter may saturate one CPU, but the other one will be free for
applications.
If the user of a uniprocessor runs another program in parallel with
the DECnet file-copying program, he should see that each program makes
progress. The file transfer slows down so it doesn't consume the whole
CPU by itself.
That FDDI adapters can keep the CPU busy is good! This means that the
CPU isn't sitting around waiting for more data from the network any more.
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| 820.2 | STAR::GILLUM | Kirt Gillum | Mon Dec 28 1992 13:23 | 9 | |
Yes, using the DEFZA will commonly eat the CPU (VAX and Alpha). The
DEFTA will correct most of this behaviour.
Something that may help use less CPU or increase throughput is to set
the SYSGEN parameter 'POOLCHECK' to 0...
Kirt
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