[comp.hypercube] iPSC Global Broadcast Times

pase@ogcvax.UUCP (09/07/87)

It occured to me that my previous postings on iPSC communication times were
incomplete without times for global broadcasts.  The iPSC has the ability to
broadcast messages as a single operation to different sub-cubes up to the
size of the whole cube.  The times posted in this article are only for global
broadcasts (i.e. broadcasts to the whole cube).  Each time is in seconds, and
is the average of 10 broadcasts.  Each broadcast was initiated by node zero,
and was echoed by node 2^d-1 (`d' is the cube dimension).  Times for smaller
sub-cubes may be treated in a future posting should there be any interest.

BTW, I'm compiling a list of functions which divulge information useful to
hypercube users.  Examples of this are routing algorithms, algorithms which
estimate message transmission time, determine the distance between two nodes,
the number and id's of nodes at a certain distance, the number of states
needed by a Markov chain to model a hypercube, etc.  Some routines apply
specifically to the iPSC (e.g. message transmission times), others do not.
Currently the list of functions is quite small but growing.  If anyone is
interested in having their routines added to this list, I would appreciate
seeing the code.  I am maintaining this library in `C', but submissions may
be in any reasonable language.  Please include the author of the algorithm,
if possible, so that proper credit may be given.  If anyone would like copies
of what I have that is fine also.  Send submissions and requests to:

	...verdix!ogcvax!pase
	...ucbvax!tektronix!ogcvax!pase
	pase@Oregon-Grad.csnet

Now for the timings I promised...  (Note the anomalous spikes on the d3
broadcast with a message of 7.5K and 8.0K bytes, and d5 with 13.5K and
14.0K bytes.  As best I am able to tell, those spikes are really there.
They appeared in every test, even when tested for alone.)
	
	                    Cube Dimension
	Message
	 Size      1       2       3       4       5
	----------------------------------------------
	 0.0K	0.0012	0.0017	0.0022	0.0027	0.0035
	 0.5K	0.0032	0.0027	0.0052	0.0047	0.0055
	 1.0K	0.0035	0.0047	0.0050	0.0065	0.0077
	 1.5K	0.0037	0.0065	0.0092	0.0125	0.0162
	 2.0K	0.0055	0.0072	0.0110	0.0150	0.0195
	 2.5K	0.0060	0.0110	0.0152	0.0185	0.0252
	 3.0K	0.0075	0.0117	0.0170	0.0225	0.0282
	 3.5K	0.0077	0.0150	0.0207	0.0255	0.0315
	 4.0K	0.0100	0.0160	0.0222	0.0295	0.0370
	 4.5K	0.0100	0.0180	0.0262	0.0347	0.0432
	 5.0K	0.0115	0.0192	0.0275	0.0345	0.0455
	 5.5K	0.0120	0.0222	0.0315	0.0410	0.0520
	 6.0K	0.0125	0.0227	0.0330	0.0432	0.0542
	 6.5K	0.0150	0.0262	0.0370	0.0487	0.0607
	 7.0K	0.0145	0.0272	0.0382	0.0505	0.0627
	 7.5K	0.0160	0.0302	0.0672	0.0557	0.0692
	 8.0K	0.0165	0.0312	0.0747	0.0575	0.0685
	 8.5K	0.0180	0.0345	0.0472	0.0607	0.0777
	 9.0K	0.0197	0.0355	0.0485	0.0645	0.0802
	 9.5K	0.0200	0.0385	0.0527	0.0677	0.0862
	10.0K	0.0207	0.0395	0.0540	0.0712	0.0887
	10.5K	0.0232	0.0427	0.0587	0.0767	0.0922
	11.0K	0.0225	0.0437	0.0597	0.0785	0.0985
	11.5K	0.0240	0.0467	0.0645	0.0835	0.1037
	12.0K	0.0247	0.0477	0.0657	0.0852	0.1060
	12.5K	0.0262	0.0510	0.0702	0.0982	0.1472
	13.0K	0.0267	0.0520	0.0715	0.0920	0.1283
	13.5K	0.0282	0.0550	0.0747	0.0977	0.3422
	14.0K	0.0287	0.0577	0.0772	0.0995	0.3672
	14.5K	0.0315	0.0592	0.0805	0.1053	0.1297
	15.0K	0.0307	0.0602	0.0827	0.1070	0.1320
	15.5K	0.0325	0.0632	0.0872	0.1105	0.1380
	16.0K	0.0337	0.0642	0.0890	0.1145	0.1402

	iPSC Global Broadcast Times in Seconds (NX 3.1)

--
Doug Pase   --   ...ucbvax!tektronix!ogcvax!pase  or  pase@Oregon-Grad.csnet