Date: Tue, 20 Jan 2004 14:59:36 -0500 From: Gerrit Nagelhout <gnagelhout@sandvine.com> To: freebsd-net@freebsd.org Subject: Intel em transmit hangs with DMA packet prefetching enabled Message-ID: <FE045D4D9F7AED4CBFF1B3B813C85337021AB0FC@mail.sandvine.com>
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Hi, Recently I turned on the packet prefetching feature (register TXDMAC 0x3000, set DPP to 0). This increases the maximum transmit performance per port by about 50KPPS. Everything worked fine, until one of our applications that sends lots of data with multiple (2 - 3) mbufs per descriptor started using this feature, and the transmitter started hanging. The watchdog feature in the driver catches it, and resets the chip, after which everything is good again for a while. Has anyone else seen this behaviour before? Thanks, Gerrit Nagelhout
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