xnu-4903.221.2.tar.gz

[apple/xnu.git] / osfmk / kern / timer_call.c

diff --git a/osfmk/kern/timer_call.c b/osfmk/kern/timer_call.c
index 93c347ddd0294faa9b0d4093ca5c82adf1433278..86bd1a8df94962b31a5b5209c38bd59ce1487833 100644 (file)
--- a/osfmk/kern/timer_call.c
+++ b/osfmk/kern/timer_call.c
@@ -108,12 +108,13 @@ lck_grp_attr_t          timer_longterm_lck_grp_attr;
 #endif
 
 /*
- * The scan limit throttles processing of the longterm queue.
+ * The scan_limit throttles processing of the longterm queue.
  * If the scan time exceeds this limit, we terminate, unlock 
- * and repeat after this same interval. This prevents unbounded holding of
+ * and defer for scan_interval. This prevents unbounded holding of
  * timer queue locks with interrupts masked.
  */
-#define TIMER_LONGTERM_SCAN_LIMIT      (1ULL * NSEC_PER_MSEC)  /* 1 msec */
+#define TIMER_LONGTERM_SCAN_LIMIT      (100ULL * NSEC_PER_USEC)        /* 100 us */
+#define TIMER_LONGTERM_SCAN_INTERVAL   (100ULL * NSEC_PER_USEC)        /* 100 us */
 /* Sentinel for "scan limit exceeded": */
 #define TIMER_LONGTERM_SCAN_AGAIN      0
 
@@ -141,11 +142,13 @@ typedef struct {
        uint64_t        scan_time;      /* last time the list was scanned */
        threshold_t     threshold;      /* longterm timer threshold */
        uint64_t        scan_limit;     /* maximum scan time */
+       uint64_t        scan_interval;  /* interval between LT "escalation" scans */
        uint64_t        scan_pauses;    /* num scans exceeding time limit */
 } timer_longterm_t;
 
 timer_longterm_t               timer_longterm = {
                                        .scan_limit = TIMER_LONGTERM_SCAN_LIMIT,
+                                       .scan_interval = TIMER_LONGTERM_SCAN_INTERVAL,
                                };
 
 static mpqueue_head_t          *timer_longterm_queue = NULL;
@@ -1492,7 +1495,7 @@ timer_longterm_update_locked(timer_longterm_t *tlp)
        }
        
        /* Throttle next scan time */
-       uint64_t scan_clamp = mach_absolute_time() + tlp->scan_limit;
+       uint64_t scan_clamp = mach_absolute_time() + tlp->scan_interval;
        if (tlp->threshold.deadline_set < scan_clamp)
                tlp->threshold.deadline_set = scan_clamp;
 
@@ -1577,7 +1580,7 @@ timer_longterm_init(void)
 enum {
        THRESHOLD, QCOUNT,
        ENQUEUES, DEQUEUES, ESCALATES, SCANS, PREEMPTS,
-       LATENCY, LATENCY_MIN, LATENCY_MAX, SCAN_LIMIT, PAUSES
+       LATENCY, LATENCY_MIN, LATENCY_MAX, SCAN_LIMIT, SCAN_INTERVAL, PAUSES
 };
 uint64_t
 timer_sysctl_get(int oid)
@@ -1608,6 +1611,8 @@ timer_sysctl_get(int oid)
                return tlp->threshold.latency_max;
        case SCAN_LIMIT:
                return tlp->scan_limit;
+       case SCAN_INTERVAL:
+               return tlp->scan_interval;
        case PAUSES:
                return tlp->scan_pauses;
        default:
@@ -1745,6 +1750,9 @@ timer_sysctl_set(int oid, uint64_t value)
        case SCAN_LIMIT:
                timer_longterm.scan_limit = value;
                return KERN_SUCCESS;
+       case SCAN_INTERVAL:
+               timer_longterm.scan_interval = value;
+               return KERN_SUCCESS;
        default:
                return KERN_INVALID_ARGUMENT;
        }