Date: Mon, 09 Aug 2004 10:05:20 +0200 From: sirola@fisica.unige.it To: freebsd-net@freebsd.org Subject: retransmissions with bge driver? Message-ID: <878ycoag8v.fsf@statpro.com>
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Hello,
I'm going to set up a server with FreeBSD 4.10. While testing the
network performance, I see a lot of tcp retransmissions on both the
network cards this server have. These are identified as BCM5704C and
using the bge driver. Actually, the network cards are configured as
100baseTX <full-duplex> (no autoselection) and i get a 5% of
retransmissions. Modifying the tcp kernel configuration as follows
raises the maximum transfer rates a bit, from 70KBytes/s to
150KBytes/s which are nevertheless poor performances. The relevant
parts of my net.inet.tcp are as follows:
net.inet.tcp.inflight_enable: 1
net.inet.tcp.sendspace: 65535
net.inet.tcp.recvspace: 65535
net.inet.tcp.rexmit_min: 20
net.inet.tcp.rexmit_slop: 200
kern.ipc.nmbclusters: 32768
By the way, no errors/collisions are reported with netstat -in...
netstat -s shows
tcp:
3283167 packets sent
1934388 data packets (438813217 bytes)
20514 data packets (28327158 bytes) retransmitted
2095620 packets received
1786464 acks (for 438791442 bytes)
22570 duplicate acks
what could be the reason of all these retransmissions? Bad cabling? A
poor switch?
Thanks in advance for your help,
enrico
P.S.
If I'm writing to the wrong list, please let me know it
--
Enrico Sirola <sirola@fisica.unige.it>
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