RTEMS networking performance issue

jvegiraju at netscape.net jvegiraju at netscape.net
Thu Jul 18 19:30:38 UTC 2002

   I am working on porting RTEMS networking code to ARM9 processor based system.
The ttcp benchmark test gives me 12Mbps data throughput for TCP test on a 100Mbps switched connection(The RTEMS box is directly connected a linux box). 
Here are some details about the test setup.
I am using RTEMS 4.5 release and ttcp app from netdemos-4.5.
The task priorities are,
   netdaemon task - 100, enet_drv_tx_daemon - 75, enet_drv_rx_daemon - 75,
   ttcp app task - 150.
The ethernet driver has a TX queue. The queue size is never going beyond  3 packets(while transmitting from RTEMS side to linux side). I see a TCP ACK from linux box after every two packets that it receives.
The CPU utilization is 100% during the test. It looks like the networkdaemon task is spending too much time in either packet processing or busy waiting for an event to happen.
I am using in_cksum routine optimized for ARM. 
I am wondering where the bottleneck is.

I would appreciate your insight into this problem.

Jitendra Vegiraju

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