Messages in this thread | | | Date | Fri, 8 Oct 1999 18:49:29 -0700 (PDT) | From | Linux Lists <> | Subject | Stalls on sync PPP transmission (new card) |
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Hello, everybody,
I'm developing the Linux driver for the Cyclades-PC300, a new synchronous card from Cyclades.
I've got to the point where I can establish a PPP connection with a router and generate IP traffic through the link with telnet, FTP, etc.
However, I noticed that the TX throughput shows up as half the nominal rate, while the RX throughput goes beyond nominal. By placing a breakout (light) box on the line, I am able to see that transmission happens on stalls (it transmits, then stops for a while, then transmits again, then stops, then ...).
After following the PC300 driver flow, I figured that the "hang" doesn't happen inside its functions, yet somewhere else.
Furthermore, I noticed that the first thing that is called after a "hang" is cpc_queue_xmit (i.e., the TX function to which the hard_start_xmit pointer in the device structure points to). My question is: what could cause this function not to be called immediately by the network subsystem as soon as TX data is available from the application? Since I could see that the "hang" doesn't happen inside the driver's functions, this is my best guess on what's happening with the transmission.
If you need to have a look at the src code, please let me know (it'll be GPL'd anyway ;).
Thanks in advance. Any help would be highly appreciated.
Regards, Ivan
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