Date: Thu, 24 May 2012 15:55:14 -0700 From: Kevin Oberman <kob6558@gmail.com> To: net@freebsd.org Subject: Major performance hit with ToS setting Message-ID: <CAN6yY1sLxFJ18ANO7nQqLetnJiT-K6pHC-X3yT1dWuWGa0VLUg@mail.gmail.com>
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When we set the ToS bits for less than best effort (also called scavenger) on packets (ToS=32), performance on FreeBSD 8.2 is terrible. It was as good as best effort on FreeBSD 7.3 (assuming no congestion). I will look into what 9 does, but does anyone have an idea of why 8.2 behaves so badly when ToS is set to 32? Here is an example of what happens to performance: nuttcp with ToS=0: 622.5000 MB / 1.00 sec = 5221.7570 Mbps 623.3125 MB / 1.00 sec = 5228.5883 Mbps 624.0000 MB / 1.00 sec = 5234.4495 Mbps With ToS=32 (0x20): 0.3750 MB / 1.00 sec = 3.1457 Mbps 0.5000 MB / 1.00 sec = 4.1942 Mbps 0.5000 MB / 1.00 sec = 4.1942 Mbps This is,of course, on a 10G interface. On 7.3 there is little difference between the two. We are using cubic CC on the 8.2 system. -- R. Kevin Oberman, Network Engineer E-mail: kob6558@gmail.com
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