Date: Fri, 11 Dec 1998 03:13:22 +1100 From: Bruce Evans <bde@zeta.org.au> To: freebsd-current@FreeBSD.ORG, gallatin@cs.duke.edu Subject: Re: increased UDP latencies in -current Message-ID: <199812101613.DAA16454@godzilla.zeta.org.au>
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>In the process of doing some Myrinet benchmarks, I noticed that UDP
>latencies have increased markedly after upgrading from 2.2.5-stable to
>3.0-current.
I see the opposite of this, if anything, for -current vs 2.2.6-2.2.7.
>On identical machines (300Mhz PII, 440lx chipset, same memory
>configuration) a kernel built from circa Jan. 18, 1998 2.2-stable
>sources yields UDP small message latencies about 10% better than a
>3.0-current kernel using both the netperf UDP_RR test & HBench-OS's
>lat_udp. A 3.0 kernel from mid July yields slightly better results
>than a recent -current, but not by much.
>
>Tests run across the loopback interface for a 1 byte message:
>
> RR/sec via us/msg via
>OS rev netperf(1) HBench-OS(2)
>--------- -------- ----------
>2.2.5 15502.17 56.6806
>3.0 (July 7) 13787.90 64.9367
>3.0 (Dec 1) 13656.60 66.5090
>
>(1)netperf2.1pl3, run via netperf -tUDP_RR -l60 -i 10,2 -Hlocalhost
>(2)hbench: lat_udp.c,v 1.4 1997/06/27 00:33:58 abrown Exp $, run as
> lat_udp 10000 localhost
On a K6/233, VIA2 chipset:
lmbench-1.x "lat_udp localhost"
--------
2.2.5-2.2.6 about 85
-current about 80
Other not very careful lmbench-2 tests show a 10% UDP time bloat in my
version of -current over the last 18 months:
*Local* Communication latencies in microseconds - smaller is better
-------------------------------------------------------------------
Host OS 2p/0K Pipe AF UDP RPC/ TCP RPC/ TCP
ctxsw UNIX UDP TCP conn
--------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
gamplex.b FreeBSD 2.2.6 9 34 41 85 155 91 199 351
gamplex.b FreeBSD 3.0-C 14 30 32 71 161 79 202 575
gamplex.b FreeBSD 3.0-C 13 28 31 70 75 190 653
gamplex.b FreeBSD 3.0-C 7 26 33 79 91 207
gamplex.b FreeBSD 3.0-C 7 27 34 74 83 209
gamplex.b FreeBSD 3.0-C 7 29 34 78 85 207
gamplex.b FreeBSD 3.0-C 7 26 35 85 80 211
gamplex.b FreeBSD 3.0-C 8 27 35 88 79
gamplex.b FreeBSD 3.0-C 5 25 36 75 161 77 217
gamplex.b FreeBSD 3.0-C 7 27 36 82 176 85 216
gamplex.b FreeBSD 3.0-C 6 27 35 80 82 210
gamplex.b Linux 2.1.128 6 28 52 74 169 92 222
Bruce
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