Mercurial > jdk8-mips64-public > hotspot / file comparison
comparison: src/os/solaris/vm/os_solaris.cpp
src/os/solaris/vm/os_solaris.cpp
- changeset 6667
- 917873d2983d
- parent 6556
- 6048424d3865
- child 6782
- f73af4455d7d
- child 6911
- ce8f6bb717c9
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| 6666:a062c3691003 | 6667:917873d2983d |
|---|---|
| 413 return Solaris::physical_memory(); | 413 return Solaris::physical_memory(); |
| 414 } | 414 } |
| 415 | 415 |
| 416 static hrtime_t first_hrtime = 0; | 416 static hrtime_t first_hrtime = 0; |
| 417 static const hrtime_t hrtime_hz = 1000*1000*1000; | 417 static const hrtime_t hrtime_hz = 1000*1000*1000; |
| 418 const int LOCK_BUSY = 1; | |
| 419 const int LOCK_FREE = 0; | |
| 420 const int LOCK_INVALID = -1; | |
| 421 static volatile hrtime_t max_hrtime = 0; | 418 static volatile hrtime_t max_hrtime = 0; |
| 422 static volatile int max_hrtime_lock = LOCK_FREE; // Update counter with LSB as lock-in-progress | |
| 423 | 419 |
| 424 | 420 |
| 425 void os::Solaris::initialize_system_info() { | 421 void os::Solaris::initialize_system_info() { |
| 426 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); | 422 set_processor_count(sysconf(_SC_NPROCESSORS_CONF)); |
| 427 _processors_online = sysconf (_SC_NPROCESSORS_ONLN); | 423 _processors_online = sysconf (_SC_NPROCESSORS_ONLN); |
| 1532 void* r = NULL; | 1528 void* r = NULL; |
| 1533 return thr_getspecific((thread_key_t)index, &r) != 0 ? NULL : r; | 1529 return thr_getspecific((thread_key_t)index, &r) != 0 ? NULL : r; |
| 1534 } | 1530 } |
| 1535 | 1531 |
| 1536 | 1532 |
| 1537 // gethrtime can move backwards if read from one cpu and then a different cpu | 1533 // gethrtime() should be monotonic according to the documentation, |
| 1538 // getTimeNanos is guaranteed to not move backward on Solaris | 1534 // but some virtualized platforms are known to break this guarantee. |
| 1539 // local spinloop created as faster for a CAS on an int than | 1535 // getTimeNanos() must be guaranteed not to move backwards, so we |
| 1540 // a CAS on a 64bit jlong. Also Atomic::cmpxchg for jlong is not | 1536 // are forced to add a check here. |
| 1541 // supported on sparc v8 or pre supports_cx8 intel boxes. | |
| 1542 // oldgetTimeNanos for systems which do not support CAS on 64bit jlong | |
| 1543 // i.e. sparc v8 and pre supports_cx8 (i486) intel boxes | |
| 1544 inline hrtime_t oldgetTimeNanos() { | |
| 1545 int gotlock = LOCK_INVALID; | |
| 1546 hrtime_t newtime = gethrtime(); | |
| 1547 | |
| 1548 for (;;) { | |
| 1549 // grab lock for max_hrtime | |
| 1550 int curlock = max_hrtime_lock; | |
| 1551 if (curlock & LOCK_BUSY) continue; | |
| 1552 if (gotlock = Atomic::cmpxchg(LOCK_BUSY, &max_hrtime_lock, LOCK_FREE) != LOCK_FREE) continue; | |
| 1553 if (newtime > max_hrtime) { | |
| 1554 max_hrtime = newtime; | |
| 1555 } else { | |
| 1556 newtime = max_hrtime; | |
| 1557 } | |
| 1558 // release lock | |
| 1559 max_hrtime_lock = LOCK_FREE; | |
| 1560 return newtime; | |
| 1561 } | |
| 1562 } | |
| 1563 // gethrtime can move backwards if read from one cpu and then a different cpu | |
| 1564 // getTimeNanos is guaranteed to not move backward on Solaris | |
| 1565 inline hrtime_t getTimeNanos() { | 1537 inline hrtime_t getTimeNanos() { |
| 1566 if (VM_Version::supports_cx8()) { | 1538 const hrtime_t now = gethrtime(); |
| 1567 const hrtime_t now = gethrtime(); | 1539 const hrtime_t prev = max_hrtime; |
| 1568 // Use atomic long load since 32-bit x86 uses 2 registers to keep long. | 1540 if (now <= prev) { |
| 1569 const hrtime_t prev = Atomic::load((volatile jlong*)&max_hrtime); | 1541 return prev; // same or retrograde time; |
| 1570 if (now <= prev) return prev; // same or retrograde time; | 1542 } |
| 1571 const hrtime_t obsv = Atomic::cmpxchg(now, (volatile jlong*)&max_hrtime, prev); | 1543 const hrtime_t obsv = Atomic::cmpxchg(now, (volatile jlong*)&max_hrtime, prev); |
| 1572 assert(obsv >= prev, "invariant"); // Monotonicity | 1544 assert(obsv >= prev, "invariant"); // Monotonicity |
| 1573 // If the CAS succeeded then we're done and return "now". | 1545 // If the CAS succeeded then we're done and return "now". |
| 1574 // If the CAS failed and the observed value "obs" is >= now then | 1546 // If the CAS failed and the observed value "obsv" is >= now then |
| 1575 // we should return "obs". If the CAS failed and now > obs > prv then | 1547 // we should return "obsv". If the CAS failed and now > obsv > prv then |
| 1576 // some other thread raced this thread and installed a new value, in which case | 1548 // some other thread raced this thread and installed a new value, in which case |
| 1577 // we could either (a) retry the entire operation, (b) retry trying to install now | 1549 // we could either (a) retry the entire operation, (b) retry trying to install now |
| 1578 // or (c) just return obs. We use (c). No loop is required although in some cases | 1550 // or (c) just return obsv. We use (c). No loop is required although in some cases |
| 1579 // we might discard a higher "now" value in deference to a slightly lower but freshly | 1551 // we might discard a higher "now" value in deference to a slightly lower but freshly |
| 1580 // installed obs value. That's entirely benign -- it admits no new orderings compared | 1552 // installed obsv value. That's entirely benign -- it admits no new orderings compared |
| 1581 // to (a) or (b) -- and greatly reduces coherence traffic. | 1553 // to (a) or (b) -- and greatly reduces coherence traffic. |
| 1582 // We might also condition (c) on the magnitude of the delta between obs and now. | 1554 // We might also condition (c) on the magnitude of the delta between obsv and now. |
| 1583 // Avoiding excessive CAS operations to hot RW locations is critical. | 1555 // Avoiding excessive CAS operations to hot RW locations is critical. |
| 1584 // See http://blogs.sun.com/dave/entry/cas_and_cache_trivia_invalidate | 1556 // See https://blogs.oracle.com/dave/entry/cas_and_cache_trivia_invalidate |
| 1585 return (prev == obsv) ? now : obsv ; | 1557 return (prev == obsv) ? now : obsv; |
| 1586 } else { | |
| 1587 return oldgetTimeNanos(); | |
| 1588 } | |
| 1589 } | 1558 } |
| 1590 | 1559 |
| 1591 // Time since start-up in seconds to a fine granularity. | 1560 // Time since start-up in seconds to a fine granularity. |
| 1592 // Used by VMSelfDestructTimer and the MemProfiler. | 1561 // Used by VMSelfDestructTimer and the MemProfiler. |
| 1593 double os::elapsedTime() { | 1562 double os::elapsedTime() { |
