How to speed up uucp with Telebits(only getting 800 chars/sec )
George Robbins
grr at cbmvax.UUCP
Mon Jul 10 06:15:02 AEST 1989
In article <7102 at swlabs.UUCP> jack at swlabs.UUCP (Jack Bonn) writes:
> In article <1989Jul8.042330.19789 at wobble.uucp> dlu at wobble.UUCP (Doug Urner) writes:
> > The best I have been able to do between
> >wobble and uunet (both Trailblazer+'s and both running the link to the modem
> >at 19.2) is in the same range.
....
> > but to uunet better than 900 is a real surprise. Any thoughts?
...
> I think the problem is with uunet. Both pcrat (Rick Richardson) and I are
> getting reduced throughputs to uunet. Let me look:
>
> System Mode Bytes Ave. CPS Burst CPS
> uunet Rcvd 3430 1706 1776
> uunet Sent 1006756 690 982
>
> This is on their (Non ATT) 800 line. Looks like uunet doesn't have
> enough horsepower here. What are you other folks getting for throughput?
Well, it's hard to make good estimates about performance without having
some sense of the activity level at the far end. I seem 1200 cps type
rates when my system (a 785) is unloaded and presumably uunet is lightly
loaded. As soon as a news unbatching or batching run starts up on my
machine, the speed drops by as much as 50%. The long term averages are
pretty consistant though.
I've attached some statistics for uunet and another system 'bpa' for
comparison. The report is from an awk script that analyzes my SYSLOG
file. Transfers are dropped in bins depending on the length of the
transfer and apparent speed. Transfers of < 256 bytes are assumed
to be itty bitty control files where the overhead is so large in
comparision to the transmision time they are dumped in their own bin.
Transfers with an effective speed of less thant 2500 bps are assumed
to have taken place over 2400 BPS modems, which is a more or less
supportable assumption.
In examining these statistics, it is important to understand that the
'transmit' times reported by uucp with a Trailblazer tend to be completely
bogus! The trailblazer buffers several (4->32k?) of data and claims it
is 'done' before this data has actually been transmitted. The effect is
that the first [buffer size] of any transfer can go as fast as 19.2KBPS
and since most uucp transfers tend to be pretty small files, the tranmit
times are badly skewed by this reporting retry.
For a concrete expample. I recently changed the news batch size for
bpa from 50K-byte to 250K-byte. Prior to this change, transmit rate
averaged ~33% faster than receive, afterwards the disparity was chopped
by a factor of two.
What does this mean in terms of uunet/trailblazer performance?
As the administrator of a fairly large multi-user unix system, I sense
maybe half the "slowdown" is on my end. As long the overall transfer
rate is about 4 times what I'd get on an olde fashioned 2400 baud modem,
I'm fairly content. Someone running a lightly loaded hotshot 386 system
might feel that sluggish performance on the part of uunet is costing them
some bucks.
The question of whether trailblazers are really 'faster' in the long run
than a 'constant speed' V.32 modem remains an open issue. By the way,
we dial directly into uunet over telco/AT&T lines. Anybody using various
economy connections or dialing out thru a PBX might want to try it straight
and see what effect this has.
It would nice if Rick would publish some statistics on his end. We've
shoved > 100M-Byte/month from/to uunet for the last 3 months and are only
one of many sites. Another report I have indicates we move 14 M-byte/day
over an average of .41 active transfers at any given time. I suspect
Rick's numbers might be a teensy bit larger.
uunet
================================================================================
system transfer files fail M-bytes hours speed peak retry
======= ============ ====== ==== ======== ====== ===== ===== =====
March 1989:
uunet fast receive 1768 0 23.678 9:27 6959 bps 13334 bps
fast send 697 0 5.984 1:31 10941 bps 15371 bps 0.2%
slow receive 958 0 11.510 16:10 1976 bps 2444 bps
slow send 252 0 3.206 4:45 1869 bps 2466 bps 0.2%
misc control 3664 0 0.375 1:09
April 1989:
uunet fast receive 3615 0 98.890 36:00 7630 bps 13277 bps
fast send 724 0 6.426 1:43 10339 bps 16840 bps 0.1%
slow receive 227 0 1.931 3:19 1613 bps 2500 bps
slow send 15 0 0.080 0:06 1979 bps 2376 bps
misc control 4794 0 0.506 1:45
May 1989:
uunet fast receive 3703 0 132.472 48:49 7535 bps 13508 bps
fast send 791 0 7.189 1:53 10600 bps 16987 bps 0.1%
slow receive 166 0 0.949 1:39 1587 bps 2457 bps
slow send 4 0 0.005 0:01 869 bps
misc control 4769 0 0.463 1:50
June 1989:
uunet fast receive 3312 0 109.088 42:06 7195 bps 13792 bps
fast send 560 0 4.111 1:02 10889 bps 16568 bps 0.3%
slow receive 154 0 1.257 1:53 1844 bps 2494 bps
slow send 6 0 0.012 0:01 1329 bps 1165 bps
misc control 4167 0 0.396 1:41
July 1989:
uunet fast receive 741 0 26.443 9:18 7888 bps 13664 bps
fast send 117 0 0.954 0:12 12565 bps 16017 bps
slow receive 25 0 0.263 0:22 1966 bps 2402 bps
misc control 953 0 0.102 0:21
bpa
================================================================================
system transfer files fail M-bytes hours speed peak retry
======= ============ ====== ==== ======== ====== ===== ===== =====
January 1989:
bpa fast receive 5982 0 73.066 24:15 8368 bps 13437 bps
fast send 550 0 12.014 2:44 12192 bps 17186 bps
slow receive 190 0 2.297 3:05 2067 bps 2499 bps
slow send 22 0 0.454 0:34 2191 bps 2263 bps
misc control 6764 0 0.868 2:40
February 1989:
bpa fast receive 5902 0 73.180 25:17 8037 bps 13042 bps
fast send 518 0 12.190 2:55 11587 bps 17260 bps
slow receive 206 0 2.527 3:17 2137 bps 2490 bps
slow send 30 0 0.544 0:41 2195 bps 2270 bps
misc control 6666 0 0.854 2:40
March 1989:
bpa fast receive 5509 0 70.681 28:25 6905 bps 13103 bps
fast send 1246 0 36.633 9:35 10609 bps 17076 bps 0.1%
slow receive 890 0 11.174 14:33 2131 bps 2495 bps
slow send 547 0 15.830 20:13 2174 bps 2301 bps 0.1%
misc control 8210 0 0.966 2:58
April 1989:
bpa fast receive 6120 0 74.420 28:28 7259 bps 13208 bps
fast send 2549 0 73.646 19:03 10730 bps 16847 bps 0.1%
slow receive 241 0 2.783 3:46 2047 bps 2458 bps
slow send 245 0 6.993 8:54 2179 bps 2211 bps
misc control 9175 0 1.015 3:01
May 1989:
bpa fast receive 6061 0 74.971 29:25 7076 bps 13252 bps
fast send 2633 0 76.044 19:43 10704 bps 17543 bps 0.1%
slow receive 747 0 9.115 12:21 2049 bps 2499 bps
slow send 594 0 17.043 21:35 2192 bps 2461 bps 0.1%
misc control 10047 0 1.096 3:11
June 1989:
bpa fast receive 4561 0 57.710 23:36 6788 bps 13206 bps
fast send 1787 0 52.122 13:48 10490 bps 17553 bps 0.1%
slow receive 1383 0 16.984 22:29 2097 bps 2489 bps
slow send 1221 0 35.541 44:40 2210 bps 2486 bps 0.1%
misc control 8960 0 0.964 2:50
July 1989:
bpa fast receive 1208 0 14.708 5:37 7253 bps 12603 bps
fast send 140 0 10.263 3:14 8817 bps 17288 bps 0.1%
slow receive 255 0 3.292 4:19 2110 bps 2465 bps
slow send 75 0 6.941 8:48 2187 bps 2388 bps
misc control 1680 0 0.208 0:40
--
George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing arpa: cbmvax!grr at uunet.uu.net
Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)
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