Date: Sun, 13 Apr 2003 19:38:05 -0000 From: Borje Josefsson <bj@dc.luth.se> To: Terry Lambert <tlambert2@mindspring.com> Cc: David Gilbert <dgilbert@velocet.ca> Subject: Re: tcp_output starving -- is due to mbuf get delay? Message-ID: <200304131827.h3DIRv2F004468@dc.luth.se> In-Reply-To: Your message of Fri, 11 Apr 2003 09:32:51 PDT. <3E96EE33.FAF4FABB@mindspring.com>
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On Fri, 11 Apr 2003 09:32:51 PDT Terry Lambert wrote:
> See other posting; I listed a bunch of OIDs to play with.
> =
> One other, if you are running -CURRENT, would be:
> =
> net.isr.netisr_enable -> 1
I found "net.isr.enable", I hope that is what You mean.
> This basically implements part 1 of 3 of LRP, which should
> reduce your per packet latency by about 50ms +/- 50ms.
> =
> Note: The logic here is inverted; you'd expect "0=3DNo NETISR",
> but it's just the opposite.
I tried to install -current on a third system (just a PIII-933, with 33MH=
z =
bus) today:
root@stinky 4# ttcp -s -t -f m -l 61440 -n 20345 dino
ttcp-t: buflen=3D61440, nbuf=3D20345, align=3D16384/0, port=3D5001 tcp -=
> dino
ttcp-t: socket
ttcp-t: connect
ttcp-t: 1249996800 bytes in 27.04 real seconds =3D 352.65 Mbit/sec +++
ttcp-t: 20345 I/O calls, msec/call =3D 1.36, calls/sec =3D 752.31
ttcp-t: 0.0user 15.6sys 0:27real 57% 15i+359d 420maxrss 0+0pf 16+44950csw=
root@stinky 5# =
root@stinky 5# sysctl net.isr.enable=3D1
net.isr.enable: 0 -> 1
root@stinky 6# ttcp -s -t -f m -l 61440 -n 20345 dino
ttcp-t: buflen=3D61440, nbuf=3D20345, align=3D16384/0, port=3D5001 tcp -=
> dino
ttcp-t: socket
ttcp-t: connect
ttcp-t: 1249996800 bytes in 27.27 real seconds =3D 349.70 Mbit/sec +++
ttcp-t: 20345 I/O calls, msec/call =3D 1.37, calls/sec =3D 746.03
ttcp-t: 0.0user 16.4sys 0:27real 60% 15i+355d 420maxrss 0+0pf 15+70547csw=
I.e. no change. The same host with NetBSD gives me at least 525 Mbit/sec.=
The symptoms with -current are the same as before. 100% CPU load.
Note the strange behaviour on netstat below. I start at 50kpps (output), =
and then fall back to 27,5k (steady).
input (Total) output
packets errs bytes packets errs bytes colls
16177 0 1067840 28767 0 43555599 0
28563 0 1885158 50583 0 76573756 0
28566 0 1885356 50582 0 76575270 0
28492 0 1880472 50451 0 76381478 0
28538 0 1883508 50534 0 76511682 0
27723 0 1829718 49096 0 74325466 0
15173 0 1001418 27498 0 41628940 0
15268 0 1007688 27581 0 41755578 0
15230 0 1005180 27498 0 41628732 0
15280 0 1008480 27498 0 41627892 0
15290 0 1009140 27624 0 41820384 0
15244 0 1006104 27498 0 41628172 0
15229 0 1005114 27498 0 41628108 0
15287 0 1008942 27540 0 41692056 0
15200 0 1003194 27413 0 41500866 0
15292 0 1009272 27625 0 41820522 0
15221 0 1004586 27411 0 41498918 0
15239 0 1005774 27540 0 41692552 0
15206 0 1003596 27540 0 41692752 0
15265 0 1007490 27584 0 41756928 0
15222 0 1004652 27539 0 41691102 0
15209 0 1003794 27540 0 41692944 0
15185 0 1002210 27496 0 41627448 0
15253 0 1006698 27540 0 41693344 0
15191 0 1002606 27496 0 41626656 0
15176 0 1001616 27540 0 41692880 0
15232 0 1005312 27627 0 41821342 0
2876 0 189816 5183 0 7838606 0
stinky# netstat -ss
tcp:
863330 packets sent
863320 data packets (1250011712 bytes)
1 data packet (1448 bytes) retransmitted
9 ack-only packets (0 delayed)
1 control packet
483425 packets received
446021 acks (for 1250011665 bytes)
29 packets (1344 bytes) received in-sequence
37376 window update packets
1 connection request
1 connection established (including accepts)
1 connection updated cached RTT on close
1 connection updated cached RTT variance on close
446021 segments updated rtt (of 21215 attempts)
11864 correct ACK header predictions
26 correct data packet header predictions
If time permits tomorrow, I'll install -current on one of the faster =
hosts, but I don't think it will make any significant difference.
--B=F6rje
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