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Index: sys/dev/hwpmc/hwpmc_logging.c
===================================================================
--- sys/dev/hwpmc/hwpmc_logging.c
+++ sys/dev/hwpmc/hwpmc_logging.c
@@ -234,7 +234,7 @@
static void pmclog_release(struct pmc_owner *po);
static uint32_t *pmclog_reserve(struct pmc_owner *po, int length);
static void pmclog_schedule_io(struct pmc_owner *po, int wakeup);
-static void pmclog_schedule_all(struct pmc_owner *po, int force);
+static void pmclog_schedule_all(struct pmc_owner *po);
static void pmclog_stop_kthread(struct pmc_owner *po);
/*
@@ -842,7 +842,7 @@
goto error;
}
- pmclog_schedule_all(po, force);
+ pmclog_schedule_all(po);
error:
mtx_unlock(&pmc_kthread_mtx);
@@ -850,7 +850,7 @@
}
static void
-pmclog_schedule_one_cond(struct pmc_owner *po, int force)
+pmclog_schedule_one_cond(struct pmc_owner *po)
{
struct pmclog_buffer *plb;
int cpu;
@@ -860,8 +860,7 @@
/* tell hardclock not to run again */
if (PMC_CPU_HAS_SAMPLES(cpu))
PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
- if (force)
- pmc_flush_samples(cpu);
+
plb = po->po_curbuf[cpu];
if (plb && plb->plb_ptr != plb->plb_base)
pmclog_schedule_io(po, 1);
@@ -869,7 +868,7 @@
}
static void
-pmclog_schedule_all(struct pmc_owner *po, int force)
+pmclog_schedule_all(struct pmc_owner *po)
{
/*
* Schedule the current buffer if any and not empty.
@@ -878,7 +877,7 @@
thread_lock(curthread);
sched_bind(curthread, i);
thread_unlock(curthread);
- pmclog_schedule_one_cond(po, force);
+ pmclog_schedule_one_cond(po);
}
thread_lock(curthread);
sched_unbind(curthread);
@@ -905,7 +904,7 @@
/*
* Schedule the current buffer.
*/
- pmclog_schedule_all(po, 0);
+ pmclog_schedule_all(po);
wakeup_one(po);
mtx_unlock(&pmc_kthread_mtx);
Index: sys/dev/hwpmc/hwpmc_mod.c
===================================================================
--- sys/dev/hwpmc/hwpmc_mod.c
+++ sys/dev/hwpmc/hwpmc_mod.c
@@ -211,7 +211,7 @@
#endif
static int load(struct module *module, int cmd, void *arg);
-static int pmc_add_sample(int ring, struct pmc *pm, struct trapframe *tf);
+static int pmc_add_sample(ring_type_t ring, struct pmc *pm, struct trapframe *tf);
static void pmc_add_thread_descriptors_from_proc(struct proc *p,
struct pmc_process *pp);
static int pmc_attach_process(struct proc *p, struct pmc *pm);
@@ -249,7 +249,7 @@
static void pmc_process_exit(void *arg, struct proc *p);
static void pmc_process_fork(void *arg, struct proc *p1,
struct proc *p2, int n);
-static void pmc_process_samples(int cpu, int soft);
+static void pmc_process_samples(int cpu, ring_type_t soft);
static void pmc_release_pmc_descriptor(struct pmc *pmc);
static void pmc_process_thread_add(struct thread *td);
static void pmc_process_thread_delete(struct thread *td);
@@ -342,6 +342,7 @@
SYSCTL_INT(_kern_hwpmc, OID_AUTO, nsamples, CTLFLAG_RDTUN,
&pmc_nsamples, 0, "number of PC samples per CPU");
+static uint64_t pmc_sample_mask = PMC_NSAMPLES-1;
/*
* kern.hwpmc.mtxpoolsize -- number of mutexes in the mutex pool.
@@ -1402,6 +1403,10 @@
if (pm->pm_state != PMC_STATE_RUNNING)
continue;
+ KASSERT(counter_u64_fetch(pm->pm_runcount) >= 0,
+ ("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
+ (unsigned long)counter_u64_fetch(pm->pm_runcount)));
+
/* increment PMC runcount */
counter_u64_add(pm->pm_runcount, 1);
@@ -1596,6 +1601,10 @@
if (pm->pm_pcpu_state[cpu].pps_stalled == 0)
pcd->pcd_stop_pmc(cpu, adjri);
+ KASSERT(counter_u64_fetch(pm->pm_runcount) > 0,
+ ("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
+ (unsigned long)counter_u64_fetch(pm->pm_runcount)));
+
/* reduce this PMC's runcount */
counter_u64_add(pm->pm_runcount, -1);
@@ -2725,7 +2734,7 @@
static void
pmc_wait_for_pmc_idle(struct pmc *pm)
{
-#ifdef HWPMC_DEBUG
+#ifdef INVARIANTS
volatile int maxloop;
maxloop = 100 * pmc_cpu_max();
@@ -2737,7 +2746,7 @@
pmclog_flush(pm->pm_owner, 1);
while (counter_u64_fetch(pm->pm_runcount) > 0) {
pmclog_flush(pm->pm_owner, 1);
-#ifdef HWPMC_DEBUG
+#ifdef INVARIANTS
maxloop--;
KASSERT(maxloop > 0,
("[pmc,%d] (ri%d, rc%ld) waiting too long for "
@@ -4657,7 +4666,7 @@
*/
static int
-pmc_add_sample(int ring, struct pmc *pm, struct trapframe *tf)
+pmc_add_sample(ring_type_t ring, struct pmc *pm, struct trapframe *tf)
{
int error, cpu, callchaindepth, inuserspace;
struct thread *td;
@@ -4672,19 +4681,20 @@
cpu = curcpu;
psb = pmc_pcpu[cpu]->pc_sb[ring];
inuserspace = TRAPF_USERMODE(tf);
- ps = psb->ps_write;
- if (ps->ps_nsamples == PMC_SAMPLE_INUSE) {
- counter_u64_add(ps->ps_pmc->pm_runcount, -1);
- counter_u64_add(pmc_stats.pm_overwrites, 1);
- ps->ps_nsamples = 0;
- } else if (ps->ps_nsamples) { /* in use, reader hasn't caught up */
+ ps = PMC_PROD_SAMPLE(psb);
+ if (psb->ps_considx != psb->ps_prodidx &&
+ ps->ps_nsamples) { /* in use, reader hasn't caught up */
pm->pm_pcpu_state[cpu].pps_stalled = 1;
counter_u64_add(pmc_stats.pm_intr_bufferfull, 1);
PMCDBG6(SAM,INT,1,"(spc) cpu=%d pm=%p tf=%p um=%d wr=%d rd=%d",
cpu, pm, (void *) tf, inuserspace,
- (int) (psb->ps_write - psb->ps_samples),
- (int) (psb->ps_read - psb->ps_samples));
+ (int) (psb->ps_prodidx & pmc_sample_mask),
+ (int) (psb->ps_considx & pmc_sample_mask));
callchaindepth = 1;
+ KASSERT(counter_u64_fetch(pm->pm_runcount) > 0,
+ ("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
+ (unsigned long)counter_u64_fetch(pm->pm_runcount)));
+
error = ENOMEM;
goto done;
}
@@ -4692,14 +4702,8 @@
/* Fill in entry. */
PMCDBG6(SAM,INT,1,"cpu=%d pm=%p tf=%p um=%d wr=%d rd=%d", cpu, pm,
(void *) tf, inuserspace,
- (int) (psb->ps_write - psb->ps_samples),
- (int) (psb->ps_read - psb->ps_samples));
-
- KASSERT(counter_u64_fetch(pm->pm_runcount) >= 0,
- ("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
- (unsigned long)counter_u64_fetch(pm->pm_runcount)));
-
- counter_u64_add(pm->pm_runcount, 1); /* hold onto PMC */
+ (int) (psb->ps_prodidx & pmc_sample_mask),
+ (int) (psb->ps_considx & pmc_sample_mask));
td = curthread;
ps->ps_pmc = pm;
@@ -4707,13 +4711,14 @@
ps->ps_pid = td->td_proc->p_pid;
ps->ps_tid = td->td_tid;
ps->ps_tsc = pmc_rdtsc();
-
+ ps->ps_ticks = ticks;
ps->ps_cpu = cpu;
ps->ps_flags = inuserspace ? PMC_CC_F_USERSPACE : 0;
callchaindepth = (pm->pm_flags & PMC_F_CALLCHAIN) ?
pmc_callchaindepth : 1;
+ MPASS(ps->ps_pc != NULL);
if (callchaindepth == 1)
ps->ps_pc[0] = PMC_TRAPFRAME_TO_PC(tf);
else {
@@ -4737,13 +4742,14 @@
ps->ps_nsamples = PMC_SAMPLE_INUSE;
} else
ps->ps_nsamples = callchaindepth; /* mark entry as in use */
- /* increment write pointer, modulo ring buffer size */
- ps++;
- if (ps == psb->ps_fence)
- psb->ps_write = psb->ps_samples;
- else
- psb->ps_write = ps;
+ KASSERT(counter_u64_fetch(pm->pm_runcount) >= 0,
+ ("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
+ (unsigned long)counter_u64_fetch(pm->pm_runcount)));
+
+ counter_u64_add(pm->pm_runcount, 1); /* hold onto PMC */
+ /* increment write pointer */
+ psb->ps_prodidx++;
done:
/* mark CPU as needing processing */
if (callchaindepth != PMC_SAMPLE_INUSE)
@@ -4785,14 +4791,15 @@
{
struct pmc *pm;
struct thread *td;
- struct pmc_sample *ps, *ps_end;
+ struct pmc_sample *ps;
struct pmc_samplebuffer *psb;
- int nsamples, nrecords, pass;
+ uint64_t considx, prodidx;
+ int nsamples, nrecords, pass, iter;
#ifdef INVARIANTS
int ncallchains;
int nfree;
+ int start_ticks = ticks;
#endif
-
psb = pmc_pcpu[cpu]->pc_sb[ring];
td = curthread;
@@ -4810,29 +4817,30 @@
if (ring == PMC_UR)
nrecords = atomic_readandclear_32(&td->td_pmcpend);
+ for (iter = 0, considx = psb->ps_considx, prodidx = psb->ps_prodidx;
+ considx < prodidx && iter < pmc_nsamples; considx++, iter++) {
+ ps = PMC_CONS_SAMPLE_OFF(psb, considx);
+
/*
* Iterate through all deferred callchain requests.
* Walk from the current read pointer to the current
* write pointer.
*/
- ps = psb->ps_read;
- ps_end = psb->ps_write;
- do {
#ifdef INVARIANTS
if (ps->ps_nsamples == PMC_SAMPLE_FREE) {
nfree++;
- goto next;
+ continue;
}
if ((ps->ps_pmc == NULL) ||
(ps->ps_pmc->pm_state != PMC_STATE_RUNNING))
nfree++;
#endif
- if (ps->ps_nsamples != PMC_SAMPLE_INUSE)
- goto next;
- if (ps->ps_td != td)
- goto next;
+ if (ps->ps_td != td ||
+ ps->ps_nsamples == PMC_SAMPLE_INUSE ||
+ ps->ps_pmc->pm_state != PMC_STATE_RUNNING)
+ continue;
KASSERT(ps->ps_cpu == cpu,
("[pmc,%d] cpu mismatch ps_cpu=%d pcpu=%d", __LINE__,
@@ -4865,15 +4873,28 @@
if (__predict_true(nsamples < pmc_callchaindepth - 1))
nsamples += pmc_save_user_callchain(ps->ps_pc + nsamples,
pmc_callchaindepth - nsamples - 1, tf);
- wmb();
- ps->ps_nsamples = nsamples;
+
+ /*
+ * We have to prevent hardclock from potentially overwriting
+ * this sample between when we read the value and when we set
+ * it
+ */
+ spinlock_enter();
+ /*
+ * Verify that the sample hasn't been dropped in the meantime
+ */
+ if (ps->ps_nsamples == PMC_SAMPLE_INUSE) {
+ ps->ps_nsamples = nsamples;
+ /*
+ * If we couldn't get a sample, simply drop the reference
+ */
+ if (nsamples == 0)
+ counter_u64_add(pm->pm_runcount, -1);
+ }
+ spinlock_exit();
if (nrecords-- == 1)
break;
-next:
- /* increment the pointer, modulo sample ring size */
- if (++ps == psb->ps_fence)
- ps = psb->ps_samples;
- } while (ps != ps_end);
+ }
if (__predict_false(ring == PMC_UR && td->td_pmcpend)) {
if (pass == 0) {
pass = 1;
@@ -4884,60 +4905,20 @@
}
#ifdef INVARIANTS
- if (ring == PMC_HR)
- KASSERT(ncallchains > 0 || nfree > 0,
- ("[pmc,%d] cpu %d didn't find a sample to collect", __LINE__,
- cpu));
+ if ((ticks - start_ticks) > hz)
+ log(LOG_ERR, "%s took %d ticks\n", __func__, (ticks - start_ticks));
#endif
/* mark CPU as needing processing */
DPCPU_SET(pmc_sampled, 1);
}
-
-static void
-pmc_flush_ring(int cpu, int ring)
-{
- struct pmc *pm;
- struct pmc_sample *ps;
- struct pmc_samplebuffer *psb;
- int n;
-
- psb = pmc_pcpu[cpu]->pc_sb[ring];
-
- for (n = 0; n < pmc_nsamples; n++) { /* bound on #iterations */
-
- ps = psb->ps_read;
- if (ps->ps_nsamples == PMC_SAMPLE_FREE)
- goto next;
- pm = ps->ps_pmc;
- counter_u64_add(pm->pm_runcount, -1);
- ps->ps_nsamples = PMC_SAMPLE_FREE;
- /* increment read pointer, modulo sample size */
- next:
- if (++ps == psb->ps_fence)
- psb->ps_read = psb->ps_samples;
- else
- psb->ps_read = ps;
- }
-}
-
-void
-pmc_flush_samples(int cpu)
-{
- int n;
-
- for (n = 0; n < PMC_NUM_SR; n++)
- pmc_flush_ring(cpu, n);
-}
-
-
/*
* Process saved PC samples.
*/
static void
-pmc_process_samples(int cpu, int ring)
+pmc_process_samples(int cpu, ring_type_t ring)
{
struct pmc *pm;
int adjri, n;
@@ -4946,20 +4927,25 @@
struct pmc_sample *ps;
struct pmc_classdep *pcd;
struct pmc_samplebuffer *psb;
+ uint64_t delta;
KASSERT(PCPU_GET(cpuid) == cpu,
("[pmc,%d] not on the correct CPU pcpu=%d cpu=%d", __LINE__,
PCPU_GET(cpuid), cpu));
psb = pmc_pcpu[cpu]->pc_sb[ring];
+ delta = psb->ps_prodidx - psb->ps_considx;
+ MPASS(delta <= pmc_nsamples);
+ MPASS(psb->ps_considx <= psb->ps_prodidx);
+ for (n = 0; psb->ps_considx < psb->ps_prodidx; psb->ps_considx++, n++) {
+ ps = PMC_CONS_SAMPLE(psb);
- for (n = 0; n < pmc_nsamples; n++) { /* bound on #iterations */
-
- ps = psb->ps_read;
- if (ps->ps_nsamples == PMC_SAMPLE_FREE)
- break;
-
+ if (__predict_false(ps->ps_nsamples == PMC_SAMPLE_FREE))
+ continue;
pm = ps->ps_pmc;
+ /* skip non-running samples */
+ if (pm->pm_state != PMC_STATE_RUNNING)
+ goto entrydone;
KASSERT(counter_u64_fetch(pm->pm_runcount) > 0,
("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
@@ -4971,12 +4957,16 @@
("[pmc,%d] pmc=%p non-sampling mode=%d", __LINE__,
pm, PMC_TO_MODE(pm)));
- /* Ignore PMCs that have been switched off */
- if (pm->pm_state != PMC_STATE_RUNNING)
- goto entrydone;
/* If there is a pending AST wait for completion */
if (ps->ps_nsamples == PMC_SAMPLE_INUSE) {
+ /*
+ * XXX track how often we hit this as it will preferentially lose user samples
+ * for long running system calls
+ */
+ /* if sample is more than 65 ms old, drop it */
+ if (ticks - ps->ps_ticks > (hz >> 4))
+ goto entrydone;
/* Need a rescan at a later time. */
DPCPU_SET(pmc_sampled, 1);
break;
@@ -4984,8 +4974,8 @@
PMCDBG6(SAM,OPS,1,"cpu=%d pm=%p n=%d fl=%x wr=%d rd=%d", cpu,
pm, ps->ps_nsamples, ps->ps_flags,
- (int) (psb->ps_write - psb->ps_samples),
- (int) (psb->ps_read - psb->ps_samples));
+ (int) (psb->ps_prodidx & pmc_sample_mask),
+ (int) (psb->ps_considx & pmc_sample_mask));
/*
* If this is a process-mode PMC that is attached to
@@ -5008,13 +4998,11 @@
entrydone:
ps->ps_nsamples = 0; /* mark entry as free */
- counter_u64_add(pm->pm_runcount, -1);
+ KASSERT(counter_u64_fetch(pm->pm_runcount) > 0,
+ ("[pmc,%d] pm=%p runcount %ld", __LINE__, (void *) pm,
+ (unsigned long)counter_u64_fetch(pm->pm_runcount)));
- /* increment read pointer, modulo sample size */
- if (++ps == psb->ps_fence)
- psb->ps_read = psb->ps_samples;
- else
- psb->ps_read = ps;
+ counter_u64_add(pm->pm_runcount, -1);
}
counter_u64_add(pmc_stats.pm_log_sweeps, 1);
@@ -5197,11 +5185,11 @@
}
}
- counter_u64_add(pm->pm_runcount, -1);
-
- KASSERT((int) counter_u64_fetch(pm->pm_runcount) >= 0,
+ KASSERT((int) counter_u64_fetch(pm->pm_runcount) > 0,
("[pmc,%d] runcount is %d", __LINE__, ri));
+ counter_u64_add(pm->pm_runcount, -1);
+
(void) pcd->pcd_config_pmc(cpu, adjri, NULL);
}
@@ -5582,7 +5570,9 @@
(void) printf("hwpmc: tunable \"nsamples\"=%d out of "
"range.\n", pmc_nsamples);
pmc_nsamples = PMC_NSAMPLES;
- }
+ pmc_sample_mask = PMC_NSAMPLES-1;
+ } else
+ pmc_sample_mask = pmc_nsamples-1;
if (pmc_callchaindepth <= 0 ||
pmc_callchaindepth > PMC_CALLCHAIN_DEPTH_MAX) {
@@ -5658,8 +5648,6 @@
sb = malloc_domain(sizeof(struct pmc_samplebuffer) +
pmc_nsamples * sizeof(struct pmc_sample), M_PMC, domain,
M_WAITOK|M_ZERO);
- sb->ps_read = sb->ps_write = sb->ps_samples;
- sb->ps_fence = sb->ps_samples + pmc_nsamples;
KASSERT(pmc_pcpu[cpu] != NULL,
("[pmc,%d] cpu=%d Null per-cpu data", __LINE__, cpu));
@@ -5676,8 +5664,6 @@
sb = malloc_domain(sizeof(struct pmc_samplebuffer) +
pmc_nsamples * sizeof(struct pmc_sample), M_PMC, domain,
M_WAITOK|M_ZERO);
- sb->ps_read = sb->ps_write = sb->ps_samples;
- sb->ps_fence = sb->ps_samples + pmc_nsamples;
KASSERT(pmc_pcpu[cpu] != NULL,
("[pmc,%d] cpu=%d Null per-cpu data", __LINE__, cpu));
@@ -5694,8 +5680,6 @@
sb = malloc_domain(sizeof(struct pmc_samplebuffer) +
pmc_nsamples * sizeof(struct pmc_sample), M_PMC, domain,
M_WAITOK|M_ZERO);
- sb->ps_read = sb->ps_write = sb->ps_samples;
- sb->ps_fence = sb->ps_samples + pmc_nsamples;
KASSERT(pmc_pcpu[cpu] != NULL,
("[pmc,%d] cpu=%d Null per-cpu data", __LINE__, cpu));
Index: sys/sys/pmc.h
===================================================================
--- sys/sys/pmc.h
+++ sys/sys/pmc.h
@@ -936,6 +936,8 @@
uint16_t ps_flags; /* other flags */
lwpid_t ps_tid; /* thread id */
pid_t ps_pid; /* process PID or -1 */
+ int ps_ticks; /* ticks at sample time */
+ /* pad */
struct thread *ps_td; /* which thread */
struct pmc *ps_pmc; /* interrupting PMC */
uintptr_t *ps_pc; /* (const) callchain start */
@@ -946,13 +948,20 @@
#define PMC_SAMPLE_INUSE ((uint16_t) 0xFFFF)
struct pmc_samplebuffer {
- struct pmc_sample * volatile ps_read; /* read pointer */
- struct pmc_sample * volatile ps_write; /* write pointer */
+ volatile uint64_t ps_prodidx; /* producer index */
+ volatile uint64_t ps_considx; /* consumer index */
uintptr_t *ps_callchains; /* all saved call chains */
- struct pmc_sample *ps_fence; /* one beyond ps_samples[] */
struct pmc_sample ps_samples[]; /* array of sample entries */
};
+#define PMC_CONS_SAMPLE(psb) \
+ (&(psb)->ps_samples[(psb)->ps_considx & pmc_sample_mask])
+
+#define PMC_CONS_SAMPLE_OFF(psb, off) \
+ (&(psb)->ps_samples[(off) & pmc_sample_mask])
+
+#define PMC_PROD_SAMPLE(psb) \
+ (&(psb)->ps_samples[(psb)->ps_prodidx & pmc_sample_mask])
/*
* struct pmc_cpustate
@@ -1216,7 +1225,6 @@
struct trapframe *_tf);
struct pmc_mdep *pmc_mdep_alloc(int nclasses);
void pmc_mdep_free(struct pmc_mdep *md);
-void pmc_flush_samples(int cpu);
uint64_t pmc_rdtsc(void);
#endif /* _KERNEL */
#endif /* _SYS_PMC_H_ */
Index: sys/sys/pmckern.h
===================================================================
--- sys/sys/pmckern.h
+++ sys/sys/pmckern.h
@@ -67,11 +67,13 @@
#define PMC_FN_THR_EXIT_LOG 16
#define PMC_FN_PROC_CREATE_LOG 17
-#define PMC_HR 0 /* Hardware ring buffer */
-#define PMC_SR 1 /* Software ring buffer */
-#define PMC_UR 2 /* userret ring buffer */
-#define PMC_NUM_SR (PMC_UR+1)
-
+typedef enum ring_type {
+ PMC_HR = 0, /* Hardware ring buffer */
+ PMC_SR = 1, /* Software ring buffer */
+ PMC_UR = 2, /* userret ring buffer */
+ PMC_NUM_SR = PMC_UR+1
+} ring_type_t;
+
struct pmckern_procexec {
int pm_credentialschanged;
uintfptr_t pm_entryaddr;

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