Troubleshooting high CPU issues

Product Discussions ADC - Application Delivery
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  • We are looking for tips on troubleshooting high CPU usage on a pair of 5440s. We reach 95% CPU (as indicated by “show cpu overall” in the shared partition). We do run quite a few AFLEX scripts, but even after simplifying them we’re still running into 90%+ CPU regularly when doing around 95K requests/sec (HTTP ±55K, TCP±40K). Note that these are not new TCP/HTTPS connections, but requests over existing connections.
  • Total system throughput is under 10Gbps.
    • No gzip compression
    • A few HTTP templates doing header insert
    • TLS offload being done by the A10s

The question is - how do we determine what’s using all the CPU so we know what to target for optimization?

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Update in case someone else comes across this thread.
Be sure to “no axdebug” after doing packet captures - even if you stop the capture with CTRL+C, it appears that whatever causes the extra CPU usage during a capture remains after it is stopped. I suspect that most hardware offload is disabled when axdebug is active.
After running “no axdebug” in all partitions, CPU usage dropped well over 50%.