rr-debugger / rr-debugger/rr

Missed/delayed ticks interrupt in CI

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Description

See https://buildkite.com/julialang/rr/builds/1417#018ad0a0-afaf-4aa7-be67-23f12ace08aa

Test 'unexpected_exit_pid_ns_32' FAILED: : error during replay:
--------------------------------------------------
[FATAL src/PerfCounters.cc:824:read_ticks()] 
(task 245379 (rec:244028) at time 202)
-> Assertion `!counting_period || interrupt_val <= adjusted_counting_period' failed to hold. Detected 1591759 ticks, expected no more than 1573334
...
{
  real_time:9731050.354581 global_time:200, event:`SYSCALL: setpriority' (state:EXITING_SYSCALL) tid:244028, ticks:474 eax:0x0 ecx:0x0 edx:0xa ebx:0x0 esp:0xf7329e10 ebp:0xf7b2a338 esi:0x8 edi:0x0 eip:0x70000002 eflags:0x246 xcs:0x23 xss:0x2b xds 0x2b xes:0x2b xfs:0x0 xgs:0x63 orig_eax:0x61
}
{
  real_time:9731050.356321 global_time:201, event:`SYSCALLBUF_FLUSH' tid:244028, ticks:1573950
  { syscall:'write', ret:0x2, size:0x10, desched:1 }
}
{
  real_time:9731050.356498 global_time:202, event:`SCHED' tid:244028, ticks:1573950
  eax:0x565eb000 ecx:0x8094b2 edx:0x0 ebx:0x565eb000 esp:0xf7b2a328 ebp:0xf7b2a328 esi:0x8 edi:0x0 eip:0x565e8988 eflags:0x216 xcs:0x23 xss:0x2b xds:0x2b xes:0x2b xfs:0x0 xgs:0x63 orig_eax:0xffffffff
}

I don't have a good explanation for this other than "the ticks interrupt was delayed past any reasonable skid value".

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at src/PerfCounters.cc:824 and inspect the tick-count assertion involved in the unexpected_exit_pid_ns_32 replay failure. Reproduce the CI failure if possible, then determine why the ticks interrupt is delayed and verify that the test no longer reports the assertion failure.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, linux
Domain
ci-cd, devtools, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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