diff options
| -rw-r--r-- | tools/guest-diag/semfix_watch.py | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/tools/guest-diag/semfix_watch.py b/tools/guest-diag/semfix_watch.py index c0ce072..c4d45fc 100644 --- a/tools/guest-diag/semfix_watch.py +++ b/tools/guest-diag/semfix_watch.py @@ -88,9 +88,13 @@ def is_gpu(v): def guest_trace(): - """(sem kptrs, pushbuffer kptrs) from the trace ring, then clear it.""" - cmd = ("sudo sh -c 'echo > /sys/kernel/tracing/trace; sleep 2; " - "grep -E \"uvmt|uvpb\" /sys/kernel/tracing/trace | tail -8'") + """(sem kptrs, pushbuffer kptrs) from the trace ring, then clear it. + + Read *before* clearing: uvm_pushbuffer_create fires once per client and + would be wiped by a clear that races it. + """ + cmd = ("sudo sh -c 'grep -E \"uvmt|uvpb\" /sys/kernel/tracing/trace | tail -200; " + "echo > /sys/kernel/tracing/trace'") try: out = subprocess.run([VMEXEC, "exec", cmd], capture_output=True, text=True, timeout=90).stdout |