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Ensure that profile and tick probes provide a non-zero PC value.

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The idle thread may process callouts while reloading the timer in
cpu_activeclock(). In this case, provide a representative value, &cpu_idle,
instead of 0 for args[0] so that the active thread can be more easily
identified from the probe.

This addresses intermittent failures of the profile-n/tst.argtest.d test.

MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D10651
This commit is contained in:
Mark Johnston 2017-05-15 21:44:40 +00:00
parent bd101a6648
commit de3a96e3b1
1 changed files with 25 additions and 37 deletions
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62
sys/cddl/dev/profile/profile.c
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@ -266,37 +266,43 @@ sbt_to_nsec(sbintime_t sbt)
}
static void
profile_fire(void *arg)
profile_probe(profile_probe_t *prof, hrtime_t late)
{
profile_probe_percpu_t *pcpu = arg;
profile_probe_t *prof = pcpu->profc_probe;
hrtime_t late;
struct thread *td;
struct trapframe *frame;
uintfptr_t pc, upc;
#ifdef illumos
late = gethrtime() - pcpu->profc_expected;
#else
late = sbt_to_nsec(sbinuptime() - pcpu->profc_expected);
#endif
pc = 0;
upc = 0;
td = curthread;
pc = upc = 0;
/*
* td_intr_frame can be unset if this is a catch up event
* after waking up from idle sleep.
* This can only happen on a CPU idle thread.
* td_intr_frame can be unset if this is a catch-up event upon waking up
* from idle sleep. This can only happen on a CPU idle thread. Use a
* representative arg0 value in this case so that one of the probe
* arguments is non-zero.
*/
frame = curthread->td_intr_frame;
frame = td->td_intr_frame;
if (frame != NULL) {
if (TRAPF_USERMODE(frame))
upc = TRAPF_PC(frame);
else
pc = TRAPF_PC(frame);
}
dtrace_probe(prof->prof_id, pc, upc, late, 0, 0);
} else if (TD_IS_IDLETHREAD(td))
pc = (uintfptr_t)&cpu_idle;
dtrace_probe(prof->prof_id, pc, upc, late, 0, 0);
}
static void
profile_fire(void *arg)
{
profile_probe_percpu_t *pcpu = arg;
profile_probe_t *prof = pcpu->profc_probe;
hrtime_t late;
late = sbt_to_nsec(sbinuptime() - pcpu->profc_expected);
profile_probe(prof, late);
pcpu->profc_expected += pcpu->profc_interval;
callout_schedule_sbt_curcpu(&pcpu->profc_cyclic,
pcpu->profc_expected, 0, C_DIRECT_EXEC | C_ABSOLUTE);
@ -306,26 +312,8 @@ static void
profile_tick(void *arg)
{
profile_probe_t *prof = arg;
struct trapframe *frame;
uintfptr_t pc, upc;
pc = 0;
upc = 0;
/*
* td_intr_frame can be unset if this is a catch up event
* after waking up from idle sleep.
* This can only happen on a CPU idle thread.
*/
frame = curthread->td_intr_frame;
if (frame != NULL) {
if (TRAPF_USERMODE(frame))
upc = TRAPF_PC(frame);
else
pc = TRAPF_PC(frame);
}
dtrace_probe(prof->prof_id, pc, upc, 0, 0, 0);
profile_probe(prof, 0);
prof->prof_expected += prof->prof_interval;
callout_schedule_sbt(&prof->prof_cyclic,
prof->prof_expected, 0, C_DIRECT_EXEC | C_ABSOLUTE);