If a system switches back and forth between hot and cold mode,
the MCE code will print a stream of critical kernel messages.
Extend the throttling code to properly notice this, by
only printing the first hot + cold transition and omitting
the rest up to CHECK_INTERVAL (5 minutes).
This way we'll only get a single incident of:
[ 102.356584] CPU0: Temperature above threshold, cpu clock throttled (total events = 1)
[ 102.357000] Disabling lock debugging due to kernel taint
[ 102.369223] CPU0: Temperature/speed normal
Every 5 minutes. The 'total events' count tells the number of cold/hot
transitions detected, should overheating occur after 5 minutes again:
[ 402.357580] CPU0: Temperature above threshold, cpu clock throttled (total events = 24891)
[ 402.358001] CPU0: Temperature/speed normal
[ 450.704142] Machine check events logged
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
b417c9fd86