Date: Mon, 9 Aug 2004 17:35:45 +0400 From: "Nickolay A. Kritsky" <nkritsky@star-sw.com> To: sirola@fisica.unige.it Cc: freebsd-net@freebsd.org Subject: Re: retransmissions with bge driver? Message-ID: <78135817453.20040809173545@star-sw.com> In-Reply-To: <878ycoag8v.fsf@statpro.com> References: <878ycoag8v.fsf@statpro.com>
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Hello sirola, Try to switch one of the NICs to half-duplex mode. This should do the trick. Monday, August 09, 2004, 12:05:20 PM, sirola@fisica.unige.it wrote: sfui> Hello, sfui> I'm going to set up a server with FreeBSD 4.10. While testing the sfui> network performance, I see a lot of tcp retransmissions on both the sfui> network cards this server have. These are identified as BCM5704C and sfui> using the bge driver. Actually, the network cards are configured as sfui> 100baseTX <full-duplex> (no autoselection) and i get a 5% of sfui> retransmissions. Modifying the tcp kernel configuration as follows sfui> raises the maximum transfer rates a bit, from 70KBytes/s to sfui> 150KBytes/s which are nevertheless poor performances. The relevant sfui> parts of my net.inet.tcp are as follows: sfui> net.inet.tcp.inflight_enable: 1 sfui> net.inet.tcp.sendspace: 65535 sfui> net.inet.tcp.recvspace: 65535 sfui> net.inet.tcp.rexmit_min: 20 sfui> net.inet.tcp.rexmit_slop: 200 sfui> kern.ipc.nmbclusters: 32768 sfui> By the way, no errors/collisions are reported with netstat -in... sfui> netstat -s shows sfui> tcp: sfui> 3283167 packets sent sfui> 1934388 data packets (438813217 bytes) sfui> 20514 data packets (28327158 bytes) retransmitted sfui> 2095620 packets received sfui> 1786464 acks (for 438791442 bytes) sfui> 22570 duplicate acks sfui> what could be the reason of all these retransmissions? Bad cabling? A sfui> poor switch? sfui> Thanks in advance for your help, sfui> enrico sfui> P.S. sfui> If I'm writing to the wrong list, please let me know it -- Best regards, ; Nickolay A. Kritsky ; SysAdmin STAR Software LLC ; mailto:nkritsky@star-sw.com
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