CHARON-VAX/CHARON-AXP - OpenVMS fails with CPUSPINWAIT fatal bug check

Problem

CHARON-VAX/CHARON-AXP / OpenVMS fails with "Fatal BUG CHECK: CPUSPINWAIT, CPU spinwait timer expired" message

Solution

When running CHARON, there are two most typical reasons that can cause this problem:

1. CHARON node is overloaded and is unable to cope with workload. Upgrading hardware or CHARON flavor usually helps to resolve the issue.

2. The timeout which causes the bug check is managed by two internal VMS parameters and by one parameter which can be set though SYSGEN (modparams.dat).
   Internal parameters, calculated automatically on OpenVMS startup, are CPU$L_TENUSEC and CPU$L_UBDELAY. They depend on hardware (in case of CHARON – on Intel) performance and are out of our control.
   The third parameter we can manage is SGN$GL_SMP_SPINWAIT or SGN$GL_SMP_LNGSPINWAIT on older OpenVMS versions
   VMS takes these 3 parameters, multiplies them,  and uses the result to calculate the loop counter which will be used to measure the delay:

   A potential issue here is that all three source variables are LONG INT. The result (SP) is also a LONG INT. So, if the result of multiplication exceeds 2^32, it could actually result in a very small number.

   .

3. Example / OpenVMS 7.3-2 using SYSGEN

    
      You should also update the MODPARAMS.DAT file and run AUTOGEN to store the new value that must survive a reboot. Please refer to your OpenVMS version documentation.

4. .

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