Date: Wed, 11 May 2011 16:12:17 -0700 From: "Kevin Oberman" <oberman@es.net> To: net@freebsd.org Subject: Performance crash when setting TOS bits Message-ID: <20110511231217.737751CC2C@ptavv.es.net>
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Under FreeBSD 8.2 we have found that something goes haywire when TOS bits are set. When the TOS is 0 (default), we can get 9 Gbps performance with one of our test systems running perfSONAR (http://www.perfsonar.net). When we set the TOS bits to 32, the performance drops to about 4Mbps. This does not happen with FreeBSD 7.3. We ran a tcptrace on the data and found very large numbers of retransmits and duplicate ACKs. I would attach the traces, but I know the mail list would remove them. Has anyone else seen this? Any idea what might be happening? -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
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