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Index: head/sys/dev/hwpmc/hwpmc_mod.c
===================================================================
--- head/sys/dev/hwpmc/hwpmc_mod.c
+++ head/sys/dev/hwpmc/hwpmc_mod.c
@@ -1298,6 +1298,15 @@
PMCDBG3(CSW,SWI,1,"cpu=%d ri=%d new=%jd", cpu, ri, newvalue);
pcd->pcd_write_pmc(cpu, adjri, newvalue);
+
+ /* If a sampling mode PMC, reset stalled state. */
+ if (PMC_TO_MODE(pm) == PMC_MODE_TS)
+ CPU_CLR_ATOMIC(cpu, &pm->pm_stalled);
+
+ /* Indicate that we desire this to run. */
+ CPU_SET_ATOMIC(cpu, &pm->pm_cpustate);
+
+ /* Start the PMC. */
pcd->pcd_start_pmc(cpu, adjri);
}
@@ -1392,8 +1401,14 @@
("[pmc,%d] ri mismatch pmc(%d) ri(%d)",
__LINE__, PMC_TO_ROWINDEX(pm), ri));
- /* Stop hardware if not already stopped */
- if (pm->pm_stalled == 0)
+ /*
+ * Change desired state, and then stop if not stalled.
+ * This two-step dance should avoid race conditions where
+ * an interrupt re-enables the PMC after this code has
+ * already checked the pm_stalled flag.
+ */
+ CPU_CLR_ATOMIC(cpu, &pm->pm_cpustate);
+ if (!CPU_ISSET(cpu, &pm->pm_stalled))
pcd->pcd_stop_pmc(cpu, adjri);
/* reduce this PMC's runcount */
@@ -2258,8 +2273,9 @@
pmc_select_cpu(cpu);
/* switch off non-stalled CPUs */
+ CPU_CLR_ATOMIC(cpu, &pm->pm_cpustate);
if (pm->pm_state == PMC_STATE_RUNNING &&
- pm->pm_stalled == 0) {
+ !CPU_ISSET(cpu, &pm->pm_stalled)) {
phw = pmc_pcpu[cpu]->pc_hwpmcs[ri];
@@ -2695,8 +2711,15 @@
if ((error = pcd->pcd_write_pmc(cpu, adjri,
PMC_IS_SAMPLING_MODE(mode) ?
pm->pm_sc.pm_reloadcount :
- pm->pm_sc.pm_initial)) == 0)
+ pm->pm_sc.pm_initial)) == 0) {
+ /* If a sampling mode PMC, reset stalled state. */
+ if (PMC_IS_SAMPLING_MODE(mode))
+ CPU_CLR_ATOMIC(cpu, &pm->pm_stalled);
+
+ /* Indicate that we desire this to run. Start it. */
+ CPU_SET_ATOMIC(cpu, &pm->pm_cpustate);
error = pcd->pcd_start_pmc(cpu, adjri);
+ }
critical_exit();
pmc_restore_cpu_binding(&pb);
@@ -2758,6 +2781,7 @@
ri = PMC_TO_ROWINDEX(pm);
pcd = pmc_ri_to_classdep(md, ri, &adjri);
+ CPU_CLR_ATOMIC(cpu, &pm->pm_cpustate);
critical_enter();
if ((error = pcd->pcd_stop_pmc(cpu, adjri)) == 0)
error = pcd->pcd_read_pmc(cpu, adjri, &pm->pm_sc.pm_initial);
@@ -4066,7 +4090,7 @@
ps = psb->ps_write;
if (ps->ps_nsamples) { /* in use, reader hasn't caught up */
- pm->pm_stalled = 1;
+ CPU_SET_ATOMIC(cpu, &pm->pm_stalled);
atomic_add_int(&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,
@@ -4321,10 +4345,11 @@
if (pm == NULL || /* !cfg'ed */
pm->pm_state != PMC_STATE_RUNNING || /* !active */
!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)) || /* !sampling */
- pm->pm_stalled == 0) /* !stalled */
+ !CPU_ISSET(cpu, &pm->pm_cpustate) || /* !desired */
+ !CPU_ISSET(cpu, &pm->pm_stalled)) /* !stalled */
continue;
- pm->pm_stalled = 0;
+ CPU_CLR_ATOMIC(cpu, &pm->pm_stalled);
(*pcd->pcd_start_pmc)(cpu, adjri);
}
}
@@ -4443,23 +4468,31 @@
("[pmc,%d] pm %p != pp_pmcs[%d] %p",
__LINE__, pm, ri, pp->pp_pmcs[ri].pp_pmc));
- (void) pcd->pcd_stop_pmc(cpu, adjri);
-
KASSERT(pm->pm_runcount > 0,
("[pmc,%d] bad runcount ri %d rc %d",
__LINE__, ri, pm->pm_runcount));
- /* Stop hardware only if it is actually running */
- if (pm->pm_state == PMC_STATE_RUNNING &&
- pm->pm_stalled == 0) {
- pcd->pcd_read_pmc(cpu, adjri, &newvalue);
- tmp = newvalue -
- PMC_PCPU_SAVED(cpu,ri);
-
- mtx_pool_lock_spin(pmc_mtxpool, pm);
- pm->pm_gv.pm_savedvalue += tmp;
- pp->pp_pmcs[ri].pp_pmcval += tmp;
- mtx_pool_unlock_spin(pmc_mtxpool, pm);
+ /*
+ * Change desired state, and then stop if not
+ * stalled. This two-step dance should avoid
+ * race conditions where an interrupt re-enables
+ * the PMC after this code has already checked
+ * the pm_stalled flag.
+ */
+ if (CPU_ISSET(cpu, &pm->pm_cpustate)) {
+ CPU_CLR_ATOMIC(cpu, &pm->pm_cpustate);
+ if (!CPU_ISSET(cpu, &pm->pm_stalled)) {
+ (void) pcd->pcd_stop_pmc(cpu, adjri);
+ pcd->pcd_read_pmc(cpu, adjri,
+ &newvalue);
+ tmp = newvalue -
+ PMC_PCPU_SAVED(cpu,ri);
+
+ mtx_pool_lock_spin(pmc_mtxpool, pm);
+ pm->pm_gv.pm_savedvalue += tmp;
+ pp->pp_pmcs[ri].pp_pmcval += tmp;
+ mtx_pool_unlock_spin(pmc_mtxpool, pm);
+ }
}
atomic_subtract_rel_int(&pm->pm_runcount,1);
Index: head/sys/sys/pmc.h
===================================================================
--- head/sys/sys/pmc.h
+++ head/sys/sys/pmc.h
@@ -614,6 +614,7 @@
#include <sys/malloc.h>
#include <sys/sysctl.h>
+#include <sys/_cpuset.h>
#include <machine/frame.h>
@@ -729,7 +730,8 @@
pmc_value_t pm_initial; /* counting PMC modes */
} pm_sc;
- uint32_t pm_stalled; /* marks stalled sampling PMCs */
+ volatile cpuset_t pm_stalled; /* marks stalled sampling PMCs */
+ volatile cpuset_t pm_cpustate; /* CPUs where PMC should be active */
uint32_t pm_caps; /* PMC capabilities */
enum pmc_event pm_event; /* event being measured */
uint32_t pm_flags; /* additional flags PMC_F_... */

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