mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-19 00:57:49 +07:00
![]() I am seeing an issue where a CPU running perf eventually hangs.
Traces show timer interrupts happening every 4 seconds even
when a userspace task is running on the CPU. /proc/timer_list
also shows pending hrtimers have not run in over an hour,
including the scheduler.
Looking closer, decrementers_next_tb is getting set to
0xffffffffffffffff, and at that point we will never take
a timer interrupt again.
In __timer_interrupt() we set decrementers_next_tb to
0xffffffffffffffff and rely on ->event_handler to update it:
*next_tb = ~(u64)0;
if (evt->event_handler)
evt->event_handler(evt);
In this case ->event_handler is hrtimer_interrupt. This will eventually
call back through the clockevents code with the next event to be
programmed:
static int decrementer_set_next_event(unsigned long evt,
struct clock_event_device *dev)
{
/* Don't adjust the decrementer if some irq work is pending */
if (test_irq_work_pending())
return 0;
__get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt;
If irq work came in between these two points, we will return
before updating decrementers_next_tb and we never process a timer
interrupt again.
This looks to have been introduced by
|
||
---|---|---|
.. | ||
alpha | ||
arc | ||
arm | ||
arm64 | ||
avr32 | ||
blackfin | ||
c6x | ||
cris | ||
frv | ||
hexagon | ||
ia64 | ||
m32r | ||
m68k | ||
metag | ||
microblaze | ||
mips | ||
mn10300 | ||
openrisc | ||
parisc | ||
powerpc | ||
s390 | ||
score | ||
sh | ||
sparc | ||
tile | ||
um | ||
unicore32 | ||
x86 | ||
xtensa | ||
.gitignore | ||
Kconfig |