Linuxppc and MPC8255 routing performance
Hello,
I'm using Linux for PPC in a proprietary MPC8255-based hardware as an embedded router system. I've been trying both Denx's kernel (as of 2001-07-23) and linuxppc_2_4 (last week's version), and everything goes smoothly (thanks to all contributing guys...).
I have some performance numbers which I'd like to share and confront, if possible. Core clock is 132 MHZ, and bus clock 33 Mhz. Our hardware does not have a secondary (L2) cache (and I wonder if it should...):
- FTP transfer ratio through the router - 0.5 to 1.5 Mbytes/s;
- # of packets per second (best case): 2000
All tests were accomplished using two fast ethernet interfaces. Best performances where obtained with data cache disabled (yes, we had to hack linuxppc_2_4 for that...).
Does that sound ok, compared to other 8260 systems? (8255 is almost identical to 8260)
Any numbers or other feedbacks will be highly appreciated!
Best regards,
Scop, Ricardo mailto:[email protected]
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Quoted 1 line · Ricardo Scop
Does that sound ok, compared to other 8260 systems?
No, not even close. Something must be wrong with your memory interface or system. The data cache enabled should be significantly faster, and on an 8260 you can run all three fast ethernets at full speed. Using FTP as a benchmark isn't usually the best choice. You should be running carefully controlled network benchmark applications.
Thanks.
-- Dan
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Quoted 2 lines · Dan Malek
No, not even close. Something must be wrong with your memory interface or system.
OK, I'll check it out,. thanks.
Quoted 3 lines
The data cache enabled should be significantly
faster, and on an 8260 you can run all three fast ethernets at full speed.
Even without secondary (L2) cache?
Quoted 2 lines
Using FTP as a benchmark isn't usually the best choice. You
should be running carefully controlled network benchmark applications.
Err.. any suggestions, on those?
Thank you, so far!
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Quoted 7 lines · Ricardo Scop
Quoted 3 lines
Using FTP as a benchmark isn't usually the best choice. You
should be running carefully controlled network benchmark applications.Err.. any suggestions, on those?
Thank you, so far!
Netperf is most common:
I prefer netpipe:
http://www.scl.ameslab.gov/netpipe/
Either will do the job. Write yourself some scripts to do the tests and also to graph the results automatically. Just looking at the numbers as they scroll by won't give you much information on performance improvement.
-VAL
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Quoted 1 line · Ricardo Scop
Even without secondary (L2) cache?
Yes. Depending upon the application, using the "backside" memory for exclusive CPM use could be helpful.
Quoted 1 line
Err.. any suggestions, on those?
netperf comes to mind.
-- Dan
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Quoted 5 lines · Dan Malek
Quoted 1 line
Even without secondary (L2) cache?
Yes. Depending upon the application, using the "backside" memory for exclusive CPM use could be helpful.
By "backside" memory you mean ... the internal data cache, perhaps?
And, how can this be done?
[sorry for the silly questions, but I'm new to both Linux and MPC8255 memory stuff :-( ; any pointer to documentation will be very welcome, too]
Thanks again...
~ Ricardo
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Quoted 1 line · Ricardo Scop
By "backside" memory you mean ... the internal data cache, perhaps?
No, bad use of words on my part. The 8260 has a local bus that can only be accessed from the CPU core and CPM (it's not on the 60x bus). Maybe the 8255 doesn't have this feature, I don't remember.
-- Dan
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Quoted 11 lines · Dan Malek
Quoted 1 line · Ricardo Scop
By "backside" memory you mean ... the internal data cache, perhaps?
No, bad use of words on my part. The 8260 has a local bus that can only be accessed from the CPU core and CPM (it's not on the 60x bus). Maybe the 8255 doesn't have this feature, I don't remember.
-- Dan
The 8255 uses the 8260 "local bus" connections for the PCI bus.
gvb
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