Mercurial > hg > truffle
changeset 12326:1c3486050433
Merge
| author | adlertz |
|---|---|
| date | Fri, 27 Sep 2013 15:43:03 -0700 |
| parents | 510fbd28919c (diff) a07c25e4f67e (current diff) |
| children | e8e077292da3 |
| files | src/share/vm/runtime/arguments.cpp src/share/vm/runtime/globals.hpp |
| diffstat | 15 files changed, 240 insertions(+), 418 deletions(-) [+] |
line wrap: on
line diff
--- a/src/share/vm/code/codeCache.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/code/codeCache.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -124,7 +124,6 @@ int CodeCache::_number_of_nmethods_with_dependencies = 0; bool CodeCache::_needs_cache_clean = false; nmethod* CodeCache::_scavenge_root_nmethods = NULL; -nmethod* CodeCache::_saved_nmethods = NULL; int CodeCache::_codemem_full_count = 0; @@ -464,96 +463,11 @@ } #endif //PRODUCT -/** - * Remove and return nmethod from the saved code list in order to reanimate it. - */ -nmethod* CodeCache::reanimate_saved_code(Method* m) { - MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); - nmethod* saved = _saved_nmethods; - nmethod* prev = NULL; - while (saved != NULL) { - if (saved->is_in_use() && saved->method() == m) { - if (prev != NULL) { - prev->set_saved_nmethod_link(saved->saved_nmethod_link()); - } else { - _saved_nmethods = saved->saved_nmethod_link(); - } - assert(saved->is_speculatively_disconnected(), "shouldn't call for other nmethods"); - saved->set_speculatively_disconnected(false); - saved->set_saved_nmethod_link(NULL); - if (PrintMethodFlushing) { - saved->print_on(tty, " ### nmethod is reconnected"); - } - if (LogCompilation && (xtty != NULL)) { - ttyLocker ttyl; - xtty->begin_elem("nmethod_reconnected compile_id='%3d'", saved->compile_id()); - xtty->method(m); - xtty->stamp(); - xtty->end_elem(); - } - return saved; - } - prev = saved; - saved = saved->saved_nmethod_link(); - } - return NULL; -} - -/** - * Remove nmethod from the saved code list in order to discard it permanently - */ -void CodeCache::remove_saved_code(nmethod* nm) { - // For conc swpr this will be called with CodeCache_lock taken by caller - assert_locked_or_safepoint(CodeCache_lock); - assert(nm->is_speculatively_disconnected(), "shouldn't call for other nmethods"); - nmethod* saved = _saved_nmethods; - nmethod* prev = NULL; - while (saved != NULL) { - if (saved == nm) { - if (prev != NULL) { - prev->set_saved_nmethod_link(saved->saved_nmethod_link()); - } else { - _saved_nmethods = saved->saved_nmethod_link(); - } - if (LogCompilation && (xtty != NULL)) { - ttyLocker ttyl; - xtty->begin_elem("nmethod_removed compile_id='%3d'", nm->compile_id()); - xtty->stamp(); - xtty->end_elem(); - } - return; - } - prev = saved; - saved = saved->saved_nmethod_link(); - } - ShouldNotReachHere(); -} - -void CodeCache::speculatively_disconnect(nmethod* nm) { - assert_locked_or_safepoint(CodeCache_lock); - assert(nm->is_in_use() && !nm->is_speculatively_disconnected(), "should only disconnect live nmethods"); - nm->set_saved_nmethod_link(_saved_nmethods); - _saved_nmethods = nm; - if (PrintMethodFlushing) { - nm->print_on(tty, " ### nmethod is speculatively disconnected"); - } - if (LogCompilation && (xtty != NULL)) { - ttyLocker ttyl; - xtty->begin_elem("nmethod_disconnected compile_id='%3d'", nm->compile_id()); - xtty->method(nm->method()); - xtty->stamp(); - xtty->end_elem(); - } - nm->method()->clear_code(); - nm->set_speculatively_disconnected(true); -} - void CodeCache::gc_prologue() { assert(!nmethod::oops_do_marking_is_active(), "oops_do_marking_epilogue must be called"); } - void CodeCache::gc_epilogue() { assert_locked_or_safepoint(CodeCache_lock); FOR_ALL_ALIVE_BLOBS(cb) {
--- a/src/share/vm/code/codeCache.hpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/code/codeCache.hpp Fri Sep 27 15:43:03 2013 -0700 @@ -57,7 +57,6 @@ static int _number_of_nmethods_with_dependencies; static bool _needs_cache_clean; static nmethod* _scavenge_root_nmethods; // linked via nm->scavenge_root_link() - static nmethod* _saved_nmethods; // Linked list of speculatively disconnected nmethods. static void verify_if_often() PRODUCT_RETURN; @@ -167,17 +166,12 @@ static size_t capacity() { return _heap->capacity(); } static size_t max_capacity() { return _heap->max_capacity(); } static size_t unallocated_capacity() { return _heap->unallocated_capacity(); } - static bool needs_flushing() { return unallocated_capacity() < CodeCacheFlushingMinimumFreeSpace; } static double reverse_free_ratio(); static bool needs_cache_clean() { return _needs_cache_clean; } static void set_needs_cache_clean(bool v) { _needs_cache_clean = v; } static void clear_inline_caches(); // clear all inline caches - static nmethod* reanimate_saved_code(Method* m); - static void remove_saved_code(nmethod* nm); - static void speculatively_disconnect(nmethod* nm); - // Deoptimization static int mark_for_deoptimization(DepChange& changes); #ifdef HOTSWAP
--- a/src/share/vm/code/nmethod.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/code/nmethod.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -462,7 +462,6 @@ _state = alive; _marked_for_reclamation = 0; _has_flushed_dependencies = 0; - _speculatively_disconnected = 0; _has_unsafe_access = 0; _has_method_handle_invokes = 0; _lazy_critical_native = 0; @@ -481,7 +480,6 @@ _osr_link = NULL; _scavenge_root_link = NULL; _scavenge_root_state = 0; - _saved_nmethod_link = NULL; _compiler = NULL; #ifdef HAVE_DTRACE_H @@ -686,6 +684,7 @@ _osr_entry_point = NULL; _exception_cache = NULL; _pc_desc_cache.reset_to(NULL); + _hotness_counter = NMethodSweeper::hotness_counter_reset_val(); code_buffer->copy_values_to(this); if (ScavengeRootsInCode && detect_scavenge_root_oops()) { @@ -770,6 +769,7 @@ _osr_entry_point = NULL; _exception_cache = NULL; _pc_desc_cache.reset_to(NULL); + _hotness_counter = NMethodSweeper::hotness_counter_reset_val(); code_buffer->copy_values_to(this); debug_only(verify_scavenge_root_oops()); @@ -842,6 +842,7 @@ _comp_level = comp_level; _compiler = compiler; _orig_pc_offset = orig_pc_offset; + _hotness_counter = NMethodSweeper::hotness_counter_reset_val(); // Section offsets _consts_offset = content_offset() + code_buffer->total_offset_of(code_buffer->consts()); @@ -1176,7 +1177,7 @@ // This is a private interface with the sweeper. void nmethod::mark_as_seen_on_stack() { - assert(is_not_entrant(), "must be a non-entrant method"); + assert(is_alive(), "Must be an alive method"); // Set the traversal mark to ensure that the sweeper does 2 // cleaning passes before moving to zombie. set_stack_traversal_mark(NMethodSweeper::traversal_count()); @@ -1261,7 +1262,7 @@ set_osr_link(NULL); //set_scavenge_root_link(NULL); // done by prune_scavenge_root_nmethods - NMethodSweeper::notify(this); + NMethodSweeper::notify(); } void nmethod::invalidate_osr_method() { @@ -1351,6 +1352,15 @@ nmethod_needs_unregister = true; } + // Must happen before state change. Otherwise we have a race condition in + // nmethod::can_not_entrant_be_converted(). I.e., a method can immediately + // transition its state from 'not_entrant' to 'zombie' without having to wait + // for stack scanning. + if (state == not_entrant) { + mark_as_seen_on_stack(); + OrderAccess::storestore(); + } + // Change state _state = state; @@ -1369,11 +1379,6 @@ HandleMark hm; method()->clear_code(); } - - if (state == not_entrant) { - mark_as_seen_on_stack(); - } - } // leave critical region under Patching_lock // When the nmethod becomes zombie it is no longer alive so the @@ -1416,7 +1421,7 @@ } // Make sweeper aware that there is a zombie method that needs to be removed - NMethodSweeper::notify(this); + NMethodSweeper::notify(); return true; } @@ -1451,10 +1456,6 @@ CodeCache::drop_scavenge_root_nmethod(this); } - if (is_speculatively_disconnected()) { - CodeCache::remove_saved_code(this); - } - #ifdef SHARK ((SharkCompiler *) compiler())->free_compiled_method(insts_begin()); #endif // SHARK
--- a/src/share/vm/code/nmethod.hpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/code/nmethod.hpp Fri Sep 27 15:43:03 2013 -0700 @@ -119,7 +119,6 @@ // To support simple linked-list chaining of nmethods: nmethod* _osr_link; // from InstanceKlass::osr_nmethods_head nmethod* _scavenge_root_link; // from CodeCache::scavenge_root_nmethods - nmethod* _saved_nmethod_link; // from CodeCache::speculatively_disconnect static nmethod* volatile _oops_do_mark_nmethods; nmethod* volatile _oops_do_mark_link; @@ -165,7 +164,6 @@ // protected by CodeCache_lock bool _has_flushed_dependencies; // Used for maintenance of dependencies (CodeCache_lock) - bool _speculatively_disconnected; // Marked for potential unload bool _marked_for_reclamation; // Used by NMethodSweeper (set only by sweeper) bool _marked_for_deoptimization; // Used for stack deoptimization @@ -180,7 +178,7 @@ unsigned int _has_wide_vectors:1; // Preserve wide vectors at safepoints // Protected by Patching_lock - unsigned char _state; // {alive, not_entrant, zombie, unloaded} + volatile unsigned char _state; // {alive, not_entrant, zombie, unloaded} #ifdef ASSERT bool _oops_are_stale; // indicates that it's no longer safe to access oops section @@ -202,11 +200,18 @@ // not_entrant method removal. Each mark_sweep pass will update // this mark to current sweep invocation count if it is seen on the - // stack. An not_entrant method can be removed when there is no + // stack. An not_entrant method can be removed when there are no // more activations, i.e., when the _stack_traversal_mark is less than // current sweep traversal index. long _stack_traversal_mark; + // The _hotness_counter indicates the hotness of a method. The higher + // the value the hotter the method. The hotness counter of a nmethod is + // set to [(ReservedCodeCacheSize / (1024 * 1024)) * 2] each time the method + // is active while stack scanning (mark_active_nmethods()). The hotness + // counter is decreased (by 1) while sweeping. + int _hotness_counter; + ExceptionCache *_exception_cache; PcDescCache _pc_desc_cache; @@ -382,6 +387,10 @@ int total_size () const; + void dec_hotness_counter() { _hotness_counter--; } + void set_hotness_counter(int val) { _hotness_counter = val; } + int hotness_counter() const { return _hotness_counter; } + // Containment bool consts_contains (address addr) const { return consts_begin () <= addr && addr < consts_end (); } bool insts_contains (address addr) const { return insts_begin () <= addr && addr < insts_end (); } @@ -408,8 +417,8 @@ // alive. It is used when an uncommon trap happens. Returns true // if this thread changed the state of the nmethod or false if // another thread performed the transition. - bool make_not_entrant() { return make_not_entrant_or_zombie(not_entrant); } - bool make_zombie() { return make_not_entrant_or_zombie(zombie); } + bool make_not_entrant() { return make_not_entrant_or_zombie(not_entrant); } + bool make_zombie() { return make_not_entrant_or_zombie(zombie); } // used by jvmti to track if the unload event has been reported bool unload_reported() { return _unload_reported; } @@ -437,9 +446,6 @@ bool has_method_handle_invokes() const { return _has_method_handle_invokes; } void set_has_method_handle_invokes(bool z) { _has_method_handle_invokes = z; } - bool is_speculatively_disconnected() const { return _speculatively_disconnected; } - void set_speculatively_disconnected(bool z) { _speculatively_disconnected = z; } - bool is_lazy_critical_native() const { return _lazy_critical_native; } void set_lazy_critical_native(bool z) { _lazy_critical_native = z; } @@ -499,9 +505,6 @@ nmethod* scavenge_root_link() const { return _scavenge_root_link; } void set_scavenge_root_link(nmethod *n) { _scavenge_root_link = n; } - nmethod* saved_nmethod_link() const { return _saved_nmethod_link; } - void set_saved_nmethod_link(nmethod *n) { _saved_nmethod_link = n; } - public: // Sweeper support
--- a/src/share/vm/compiler/compileBroker.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/compiler/compileBroker.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -634,19 +634,36 @@ NMethodSweeper::possibly_sweep(); MutexLocker locker(lock()); - // Wait for an available CompileTask. + // If _first is NULL we have no more compile jobs. There are two reasons for + // having no compile jobs: First, we compiled everything we wanted. Second, + // we ran out of code cache so compilation has been disabled. In the latter + // case we perform code cache sweeps to free memory such that we can re-enable + // compilation. while (_first == NULL) { - // There is no work to be done right now. Wait. - if (UseCodeCacheFlushing && (!CompileBroker::should_compile_new_jobs() || CodeCache::needs_flushing())) { - // During the emergency sweeping periods, wake up and sweep occasionally - bool timedout = lock()->wait(!Mutex::_no_safepoint_check_flag, NmethodSweepCheckInterval*1000); - if (timedout) { + if (UseCodeCacheFlushing && !CompileBroker::should_compile_new_jobs()) { + // Wait a certain amount of time to possibly do another sweep. + // We must wait until stack scanning has happened so that we can + // transition a method's state from 'not_entrant' to 'zombie'. + long wait_time = NmethodSweepCheckInterval * 1000; + if (FLAG_IS_DEFAULT(NmethodSweepCheckInterval)) { + // Only one thread at a time can do sweeping. Scale the + // wait time according to the number of compiler threads. + // As a result, the next sweep is likely to happen every 100ms + // with an arbitrary number of threads that do sweeping. + wait_time = 100 * CICompilerCount; + } + bool timeout = lock()->wait(!Mutex::_no_safepoint_check_flag, wait_time); + if (timeout) { MutexUnlocker ul(lock()); - // When otherwise not busy, run nmethod sweeping NMethodSweeper::possibly_sweep(); } } else { - // During normal operation no need to wake up on timer + // If there are no compilation tasks and we can compile new jobs + // (i.e., there is enough free space in the code cache) there is + // no need to invoke the sweeper. As a result, the hotness of methods + // remains unchanged. This behavior is desired, since we want to keep + // the stable state, i.e., we do not want to evict methods from the + // code cache if it is unnecessary. lock()->wait(); } } @@ -1227,16 +1244,9 @@ return method_code; } } - if (method->is_not_compilable(comp_level)) return NULL; - - if (UseCodeCacheFlushing) { - nmethod* saved = CodeCache::reanimate_saved_code(method()); - if (saved != NULL) { - method->set_code(method, saved); - return saved; - } + if (method->is_not_compilable(comp_level)) { + return NULL; } - } else { // osr compilation #ifndef TIERED @@ -1585,9 +1595,6 @@ if (CodeCache::unallocated_capacity() < CodeCacheMinimumFreeSpace) { // the code cache is really full handle_full_code_cache(); - } else if (UseCodeCacheFlushing && CodeCache::needs_flushing()) { - // Attempt to start cleaning the code cache while there is still a little headroom - NMethodSweeper::handle_full_code_cache(false); } CompileTask* task = queue->get(); @@ -1943,7 +1950,11 @@ } #endif if (UseCodeCacheFlushing) { - NMethodSweeper::handle_full_code_cache(true); + // Since code cache is full, immediately stop new compiles + if (CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation)) { + NMethodSweeper::log_sweep("disable_compiler"); + NMethodSweeper::possibly_sweep(); + } } else { UseCompiler = false; AlwaysCompileLoopMethods = false;
--- a/src/share/vm/oops/method.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/oops/method.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -901,16 +901,6 @@ // This function must not hit a safepoint! address Method::verified_code_entry() { debug_only(No_Safepoint_Verifier nsv;) - nmethod *code = (nmethod *)OrderAccess::load_ptr_acquire(&_code); - if (code == NULL && UseCodeCacheFlushing) { - nmethod *saved_code = CodeCache::reanimate_saved_code(this); - if (saved_code != NULL) { - methodHandle method(this); - assert( ! saved_code->is_osr_method(), "should not get here for osr" ); - set_code( method, saved_code ); - } - } - assert(_from_compiled_entry != NULL, "must be set"); return _from_compiled_entry; }
--- a/src/share/vm/runtime/arguments.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/arguments.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -1132,6 +1132,9 @@ Tier3InvokeNotifyFreqLog = 0; Tier4InvocationThreshold = 0; } + if (FLAG_IS_DEFAULT(NmethodSweepFraction)) { + FLAG_SET_DEFAULT(NmethodSweepFraction, 1 + ReservedCodeCacheSize / (16 * M)); + } } #if INCLUDE_ALL_GCS @@ -2337,6 +2340,10 @@ (2*G)/M); status = false; } + + status &= verify_interval(NmethodSweepFraction, 1, ReservedCodeCacheSize/K, "NmethodSweepFraction"); + status &= verify_interval(NmethodSweepActivity, 0, 2000, "NmethodSweepActivity"); + return status; }
--- a/src/share/vm/runtime/globals.hpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/globals.hpp Fri Sep 27 15:43:03 2013 -0700 @@ -2871,6 +2871,10 @@ product(intx, NmethodSweepCheckInterval, 5, \ "Compilers wake up every n seconds to possibly sweep nmethods") \ \ + product(intx, NmethodSweepActivity, 10, \ + "Removes cold nmethods from code cache if > 0. Higher values " \ + "result in more aggressive sweeping") \ + \ notproduct(bool, LogSweeper, false, \ "Keep a ring buffer of sweeper activity") \ \ @@ -3242,15 +3246,6 @@ product(bool, UseCodeCacheFlushing, true, \ "Attempt to clean the code cache before shutting off compiler") \ \ - product(intx, MinCodeCacheFlushingInterval, 30, \ - "Min number of seconds between code cache cleaning sessions") \ - \ - product(uintx, CodeCacheFlushingMinimumFreeSpace, 1500*K, \ - "When less than X space left, start code cache cleaning") \ - \ - product(uintx, CodeCacheFlushingFraction, 2, \ - "Fraction of the code cache that is flushed when full") \ - \ /* interpreter debugging */ \ develop(intx, BinarySwitchThreshold, 5, \ "Minimal number of lookupswitch entries for rewriting to binary " \
--- a/src/share/vm/runtime/safepoint.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/safepoint.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -519,8 +519,8 @@ } { - TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime); - NMethodSweeper::scan_stacks(); + TraceTime t4("mark nmethods", TraceSafepointCleanupTime); + NMethodSweeper::mark_active_nmethods(); } if (SymbolTable::needs_rehashing()) {
--- a/src/share/vm/runtime/sweeper.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/sweeper.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -127,64 +127,79 @@ #define SWEEP(nm) #endif +nmethod* NMethodSweeper::_current = NULL; // Current nmethod +long NMethodSweeper::_traversals = 0; // Nof. stack traversals performed +int NMethodSweeper::_seen = 0; // Nof. nmethods we have currently processed in current pass of CodeCache +int NMethodSweeper::_flushed_count = 0; // Nof. nmethods flushed in current sweep +int NMethodSweeper::_zombified_count = 0; // Nof. nmethods made zombie in current sweep +int NMethodSweeper::_marked_count = 0; // Nof. nmethods marked for reclaim in current sweep -long NMethodSweeper::_traversals = 0; // No. of stack traversals performed -nmethod* NMethodSweeper::_current = NULL; // Current nmethod -int NMethodSweeper::_seen = 0 ; // No. of nmethods we have currently processed in current pass of CodeCache -int NMethodSweeper::_flushed_count = 0; // Nof. nmethods flushed in current sweep -int NMethodSweeper::_zombified_count = 0; // Nof. nmethods made zombie in current sweep -int NMethodSweeper::_marked_count = 0; // Nof. nmethods marked for reclaim in current sweep - -volatile int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass +volatile int NMethodSweeper::_invocations = 0; // Nof. invocations left until we are completed with this pass volatile int NMethodSweeper::_sweep_started = 0; // Whether a sweep is in progress. -jint NMethodSweeper::_locked_seen = 0; +jint NMethodSweeper::_locked_seen = 0; jint NMethodSweeper::_not_entrant_seen_on_stack = 0; -bool NMethodSweeper::_resweep = false; -jint NMethodSweeper::_flush_token = 0; -jlong NMethodSweeper::_last_full_flush_time = 0; -int NMethodSweeper::_highest_marked = 0; -int NMethodSweeper::_dead_compile_ids = 0; -long NMethodSweeper::_last_flush_traversal_id = 0; +bool NMethodSweeper::_request_mark_phase = false; -int NMethodSweeper::_number_of_flushes = 0; // Total of full traversals caused by full cache int NMethodSweeper::_total_nof_methods_reclaimed = 0; -jlong NMethodSweeper::_total_time_sweeping = 0; -jlong NMethodSweeper::_total_time_this_sweep = 0; -jlong NMethodSweeper::_peak_sweep_time = 0; -jlong NMethodSweeper::_peak_sweep_fraction_time = 0; -jlong NMethodSweeper::_total_disconnect_time = 0; -jlong NMethodSweeper::_peak_disconnect_time = 0; +jlong NMethodSweeper::_total_time_sweeping = 0; +jlong NMethodSweeper::_total_time_this_sweep = 0; +jlong NMethodSweeper::_peak_sweep_time = 0; +jlong NMethodSweeper::_peak_sweep_fraction_time = 0; +int NMethodSweeper::_hotness_counter_reset_val = 0; + class MarkActivationClosure: public CodeBlobClosure { public: virtual void do_code_blob(CodeBlob* cb) { - // If we see an activation belonging to a non_entrant nmethod, we mark it. - if (cb->is_nmethod() && ((nmethod*)cb)->is_not_entrant()) { - ((nmethod*)cb)->mark_as_seen_on_stack(); + if (cb->is_nmethod()) { + nmethod* nm = (nmethod*)cb; + nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val()); + // If we see an activation belonging to a non_entrant nmethod, we mark it. + if (nm->is_not_entrant()) { + nm->mark_as_seen_on_stack(); + } } } }; static MarkActivationClosure mark_activation_closure; +class SetHotnessClosure: public CodeBlobClosure { +public: + virtual void do_code_blob(CodeBlob* cb) { + if (cb->is_nmethod()) { + nmethod* nm = (nmethod*)cb; + nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val()); + } + } +}; +static SetHotnessClosure set_hotness_closure; + + +int NMethodSweeper::hotness_counter_reset_val() { + if (_hotness_counter_reset_val == 0) { + _hotness_counter_reset_val = (ReservedCodeCacheSize < M) ? 1 : (ReservedCodeCacheSize / M) * 2; + } + return _hotness_counter_reset_val; +} bool NMethodSweeper::sweep_in_progress() { return (_current != NULL); } -void NMethodSweeper::scan_stacks() { +// Scans the stacks of all Java threads and marks activations of not-entrant methods. +// No need to synchronize access, since 'mark_active_nmethods' is always executed at a +// safepoint. +void NMethodSweeper::mark_active_nmethods() { assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); - if (!MethodFlushing) return; - - // No need to synchronize access, since this is always executed at a - // safepoint. - - // Make sure CompiledIC_lock in unlocked, since we might update some - // inline caches. If it is, we just bail-out and try later. - if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return; + // If we do not want to reclaim not-entrant or zombie methods there is no need + // to scan stacks + if (!MethodFlushing) { + return; + } // Check for restart assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); - if (!sweep_in_progress() && _resweep) { + if (!sweep_in_progress() && need_marking_phase()) { _seen = 0; _invocations = NmethodSweepFraction; _current = CodeCache::first_nmethod(); @@ -197,30 +212,22 @@ Threads::nmethods_do(&mark_activation_closure); // reset the flags since we started a scan from the beginning. - _resweep = false; + reset_nmethod_marking(); _locked_seen = 0; _not_entrant_seen_on_stack = 0; + } else { + // Only set hotness counter + Threads::nmethods_do(&set_hotness_closure); } - if (UseCodeCacheFlushing) { - // only allow new flushes after the interval is complete. - jlong now = os::javaTimeMillis(); - jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; - jlong curr_interval = now - _last_full_flush_time; - if (curr_interval > max_interval) { - _flush_token = 0; - } - - if (!CodeCache::needs_flushing() && !CompileBroker::should_compile_new_jobs()) { - CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); - log_sweep("restart_compiler"); - } - } + OrderAccess::storestore(); } void NMethodSweeper::possibly_sweep() { assert(JavaThread::current()->thread_state() == _thread_in_vm, "must run in vm mode"); - if (!MethodFlushing || !sweep_in_progress()) return; + if (!MethodFlushing || !sweep_in_progress()) { + return; + } if (_invocations > 0) { // Only one thread at a time will sweep @@ -258,8 +265,7 @@ if (!CompileBroker::should_compile_new_jobs()) { // If we have turned off compilations we might as well do full sweeps // in order to reach the clean state faster. Otherwise the sleeping compiler - // threads will slow down sweeping. After a few iterations the cache - // will be clean and sweeping stops (_resweep will not be set) + // threads will slow down sweeping. _invocations = 1; } @@ -271,9 +277,11 @@ int todo = (CodeCache::nof_nmethods() - _seen) / _invocations; int swept_count = 0; + assert(!SafepointSynchronize::is_at_safepoint(), "should not be in safepoint when we get here"); assert(!CodeCache_lock->owned_by_self(), "just checking"); + int freed_memory = 0; { MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); @@ -299,7 +307,7 @@ // Now ready to process nmethod and give up CodeCache_lock { MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); - process_nmethod(_current); + freed_memory += process_nmethod(_current); } _seen++; _current = next; @@ -308,11 +316,11 @@ assert(_invocations > 1 || _current == NULL, "must have scanned the whole cache"); - if (!sweep_in_progress() && !_resweep && (_locked_seen || _not_entrant_seen_on_stack)) { + if (!sweep_in_progress() && !need_marking_phase() && (_locked_seen || _not_entrant_seen_on_stack)) { // we've completed a scan without making progress but there were // nmethods we were unable to process either because they were - // locked or were still on stack. We don't have to aggresively - // clean them up so just stop scanning. We could scan once more + // locked or were still on stack. We don't have to aggressively + // clean them up so just stop scanning. We could scan once more // but that complicates the control logic and it's unlikely to // matter much. if (PrintMethodFlushing) { @@ -351,9 +359,16 @@ log_sweep("finished"); } - // Sweeper is the only case where memory is released, - // check here if it is time to restart the compiler. - if (UseCodeCacheFlushing && !CompileBroker::should_compile_new_jobs() && !CodeCache::needs_flushing()) { + // Sweeper is the only case where memory is released, check here if it + // is time to restart the compiler. Only checking if there is a certain + // amount of free memory in the code cache might lead to re-enabling + // compilation although no memory has been released. For example, there are + // cases when compilation was disabled although there is 4MB (or more) free + // memory in the code cache. The reason is code cache fragmentation. Therefore, + // it only makes sense to re-enable compilation if we have actually freed memory. + // Note that typically several kB are released for sweeping 16MB of the code + // cache. As a result, 'freed_memory' > 0 to restart the compiler. + if (UseCodeCacheFlushing && (!CompileBroker::should_compile_new_jobs() && (freed_memory > 0))) { CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); log_sweep("restart_compiler"); } @@ -367,8 +382,8 @@ _thread = CompilerThread::current(); if (!nm->is_zombie() && !nm->is_unloaded()) { // Only expose live nmethods for scanning - _thread->set_scanned_nmethod(nm); - } + _thread->set_scanned_nmethod(nm); + } } ~NMethodMarker() { _thread->set_scanned_nmethod(NULL); @@ -392,20 +407,20 @@ nm->flush(); } -void NMethodSweeper::process_nmethod(nmethod *nm) { +int NMethodSweeper::process_nmethod(nmethod *nm) { assert(!CodeCache_lock->owned_by_self(), "just checking"); + int freed_memory = 0; // Make sure this nmethod doesn't get unloaded during the scan, - // since the locks acquired below might safepoint. + // since safepoints may happen during acquired below locks. NMethodMarker nmm(nm); - SWEEP(nm); // Skip methods that are currently referenced by the VM if (nm->is_locked_by_vm()) { // But still remember to clean-up inline caches for alive nmethods if (nm->is_alive()) { - // Clean-up all inline caches that points to zombie/non-reentrant methods + // Clean inline caches that point to zombie/non-entrant methods MutexLocker cl(CompiledIC_lock); nm->cleanup_inline_caches(); SWEEP(nm); @@ -413,18 +428,19 @@ _locked_seen++; SWEEP(nm); } - return; + return freed_memory; } if (nm->is_zombie()) { - // If it is first time, we see nmethod then we mark it. Otherwise, - // we reclame it. When we have seen a zombie method twice, we know that + // If it is the first time we see nmethod then we mark it. Otherwise, + // we reclaim it. When we have seen a zombie method twice, we know that // there are no inline caches that refer to it. if (nm->is_marked_for_reclamation()) { assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); if (PrintMethodFlushing && Verbose) { tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm); } + freed_memory = nm->total_size(); release_nmethod(nm); _flushed_count++; } else { @@ -432,19 +448,19 @@ tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm); } nm->mark_for_reclamation(); - _resweep = true; + request_nmethod_marking(); _marked_count++; SWEEP(nm); } } else if (nm->is_not_entrant()) { - // If there is no current activations of this method on the + // If there are no current activations of this method on the // stack we can safely convert it to a zombie method if (nm->can_not_entrant_be_converted()) { if (PrintMethodFlushing && Verbose) { tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm); } nm->make_zombie(); - _resweep = true; + request_nmethod_marking(); _zombified_count++; SWEEP(nm); } else { @@ -459,159 +475,57 @@ } } else if (nm->is_unloaded()) { // Unloaded code, just make it a zombie - if (PrintMethodFlushing && Verbose) + if (PrintMethodFlushing && Verbose) { tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm); - + } if (nm->is_osr_method()) { SWEEP(nm); // No inline caches will ever point to osr methods, so we can just remove it + freed_memory = nm->total_size(); release_nmethod(nm); _flushed_count++; } else { nm->make_zombie(); - _resweep = true; + request_nmethod_marking(); _zombified_count++; SWEEP(nm); } } else { - assert(nm->is_alive(), "should be alive"); - if (UseCodeCacheFlushing) { - if (nm->is_speculatively_disconnected() && !nm->is_locked_by_vm() && !nm->is_osr_method() && - (_traversals > _last_flush_traversal_id + 2) && (nm->compile_id() < _highest_marked)) { - // This method has not been called since the forced cleanup happened - nm->make_not_entrant(); + if (!nm->is_locked_by_vm() && !nm->is_osr_method() && !nm->is_native_method()) { + // Do not make native methods and OSR-methods not-entrant + nm->dec_hotness_counter(); + // Get the initial value of the hotness counter. This value depends on the + // ReservedCodeCacheSize + int reset_val = hotness_counter_reset_val(); + int time_since_reset = reset_val - nm->hotness_counter(); + double threshold = -reset_val + (CodeCache::reverse_free_ratio() * NmethodSweepActivity); + // The less free space in the code cache we have - the bigger reverse_free_ratio() is. + // I.e., 'threshold' increases with lower available space in the code cache and a higher + // NmethodSweepActivity. If the current hotness counter - which decreases from its initial + // value until it is reset by stack walking - is smaller than the computed threshold, the + // corresponding nmethod is considered for removal. + if ((NmethodSweepActivity > 0) && (nm->hotness_counter() < threshold) && (time_since_reset > 10)) { + // A method is marked as not-entrant if the method is + // 1) 'old enough': nm->hotness_counter() < threshold + // 2) The method was in_use for a minimum amount of time: (time_since_reset > 10) + // The second condition is necessary if we are dealing with very small code cache + // sizes (e.g., <10m) and the code cache size is too small to hold all hot methods. + // The second condition ensures that methods are not immediately made not-entrant + // after compilation. + nm->make_not_entrant(); + request_nmethod_marking(); + } } } - - // Clean-up all inline caches that points to zombie/non-reentrant methods + // Clean-up all inline caches that point to zombie/non-reentrant methods MutexLocker cl(CompiledIC_lock); nm->cleanup_inline_caches(); SWEEP(nm); } -} - -// Code cache unloading: when compilers notice the code cache is getting full, -// they will call a vm op that comes here. This code attempts to speculatively -// unload the oldest half of the nmethods (based on the compile job id) by -// saving the old code in a list in the CodeCache. Then -// execution resumes. If a method so marked is not called by the second sweeper -// stack traversal after the current one, the nmethod will be marked non-entrant and -// got rid of by normal sweeping. If the method is called, the Method*'s -// _code field is restored and the Method*/nmethod -// go back to their normal state. -void NMethodSweeper::handle_full_code_cache(bool is_full) { - - if (is_full) { - // Since code cache is full, immediately stop new compiles - if (CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation)) { - log_sweep("disable_compiler"); - } - } - - // Make sure only one thread can flush - // The token is reset after CodeCacheMinimumFlushInterval in scan stacks, - // no need to check the timeout here. - jint old = Atomic::cmpxchg( 1, &_flush_token, 0 ); - if (old != 0) { - return; - } - - VM_HandleFullCodeCache op(is_full); - VMThread::execute(&op); - - // resweep again as soon as possible - _resweep = true; + return freed_memory; } -void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) { - // If there was a race in detecting full code cache, only run - // one vm op for it or keep the compiler shut off - - jlong disconnect_start_counter = os::elapsed_counter(); - - // Traverse the code cache trying to dump the oldest nmethods - int curr_max_comp_id = CompileBroker::get_compilation_id(); - int flush_target = ((curr_max_comp_id - _dead_compile_ids) / CodeCacheFlushingFraction) + _dead_compile_ids; - - log_sweep("start_cleaning"); - - nmethod* nm = CodeCache::alive_nmethod(CodeCache::first()); - jint disconnected = 0; - jint made_not_entrant = 0; - jint nmethod_count = 0; - - while ((nm != NULL)){ - int curr_comp_id = nm->compile_id(); - - // OSR methods cannot be flushed like this. Also, don't flush native methods - // since they are part of the JDK in most cases - if (!nm->is_osr_method() && !nm->is_locked_by_vm() && !nm->is_native_method()) { - - // only count methods that can be speculatively disconnected - nmethod_count++; - - if (nm->is_in_use() && (curr_comp_id < flush_target)) { - if ((nm->method()->code() == nm)) { - // This method has not been previously considered for - // unloading or it was restored already - CodeCache::speculatively_disconnect(nm); - disconnected++; - } else if (nm->is_speculatively_disconnected()) { - // This method was previously considered for preemptive unloading and was not called since then - CompilationPolicy::policy()->delay_compilation(nm->method()); - nm->make_not_entrant(); - made_not_entrant++; - } - - if (curr_comp_id > _highest_marked) { - _highest_marked = curr_comp_id; - } - } - } - nm = CodeCache::alive_nmethod(CodeCache::next(nm)); - } - - // remember how many compile_ids wheren't seen last flush. - _dead_compile_ids = curr_max_comp_id - nmethod_count; - - log_sweep("stop_cleaning", - "disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "'", - disconnected, made_not_entrant); - - // Shut off compiler. Sweeper will start over with a new stack scan and - // traversal cycle and turn it back on if it clears enough space. - if (is_full) { - _last_full_flush_time = os::javaTimeMillis(); - } - - jlong disconnect_end_counter = os::elapsed_counter(); - jlong disconnect_time = disconnect_end_counter - disconnect_start_counter; - _total_disconnect_time += disconnect_time; - _peak_disconnect_time = MAX2(disconnect_time, _peak_disconnect_time); - - EventCleanCodeCache event(UNTIMED); - if (event.should_commit()) { - event.set_starttime(disconnect_start_counter); - event.set_endtime(disconnect_end_counter); - event.set_disconnectedCount(disconnected); - event.set_madeNonEntrantCount(made_not_entrant); - event.commit(); - } - _number_of_flushes++; - - // After two more traversals the sweeper will get rid of unrestored nmethods - _last_flush_traversal_id = _traversals; - _resweep = true; -#ifdef ASSERT - - if(PrintMethodFlushing && Verbose) { - tty->print_cr("### sweeper: unload time: " INT64_FORMAT, (jlong)disconnect_time); - } -#endif -} - - // Print out some state information about the current sweep and the // state of the code cache if it's requested. void NMethodSweeper::log_sweep(const char* msg, const char* format, ...) {
--- a/src/share/vm/runtime/sweeper.hpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/sweeper.hpp Fri Sep 27 15:43:03 2013 -0700 @@ -27,8 +27,30 @@ // An NmethodSweeper is an incremental cleaner for: // - cleanup inline caches -// - reclamation of unreferences zombie nmethods -// +// - reclamation of nmethods +// Removing nmethods from the code cache includes two operations +// 1) mark active nmethods +// Is done in 'mark_active_nmethods()'. This function is called at a +// safepoint and marks all nmethods that are active on a thread's stack. +// 2) sweep nmethods +// Is done in sweep_code_cache(). This function is the only place in the +// sweeper where memory is reclaimed. Note that sweep_code_cache() is not +// called at a safepoint. However, sweep_code_cache() stops executing if +// another thread requests a safepoint. Consequently, 'mark_active_nmethods()' +// and sweep_code_cache() cannot execute at the same time. +// To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can +// be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency +// invalidation, and (iv) being replaced be a different method version (tiered +// compilation). Not-entrant nmethod cannot be called by Java threads, but they +// can still be active on the stack. To ensure that active nmethod are not reclaimed, +// we have to wait until the next marking phase has completed. If a not-entrant +// nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely +// remove the nmethod, all inline caches (IC) that point to the the nmethod must be +// cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's +// state change happens during separate sweeps. It may take at least 3 sweeps before an +// nmethod's space is freed. Sweeping is currently done by compiler threads between +// compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache +// is full. class NMethodSweeper : public AllStatic { static long _traversals; // Stack scan count, also sweep ID. @@ -41,46 +63,38 @@ static volatile int _invocations; // No. of invocations left until we are completed with this pass static volatile int _sweep_started; // Flag to control conc sweeper - //The following are reset in scan_stacks and synchronized by the safepoint - static bool _resweep; // Indicates that a change has happend and we want another sweep, - // always checked and reset at a safepoint so memory will be in sync. - static int _locked_seen; // Number of locked nmethods encountered during the scan + //The following are reset in mark_active_nmethods and synchronized by the safepoint + static bool _request_mark_phase; // Indicates that a change has happend and we need another mark pahse, + // always checked and reset at a safepoint so memory will be in sync. + static int _locked_seen; // Number of locked nmethods encountered during the scan static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack - static jint _flush_token; // token that guards method flushing, making sure it is executed only once. - - // These are set during a flush, a VM-operation - static long _last_flush_traversal_id; // trav number at last flush unloading - static jlong _last_full_flush_time; // timestamp of last emergency unloading - - // These are synchronized by the _sweep_started token - static int _highest_marked; // highest compile id dumped at last emergency unloading - static int _dead_compile_ids; // number of compile ids that where not in the cache last flush // Stat counters - static int _number_of_flushes; // Total of full traversals caused by full cache static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed static jlong _total_time_sweeping; // Accumulated time sweeping static jlong _total_time_this_sweep; // Total time this sweep static jlong _peak_sweep_time; // Peak time for a full sweep static jlong _peak_sweep_fraction_time; // Peak time sweeping one fraction - static jlong _total_disconnect_time; // Total time cleaning code mem - static jlong _peak_disconnect_time; // Peak time cleaning code mem - static void process_nmethod(nmethod *nm); + static int process_nmethod(nmethod *nm); static void release_nmethod(nmethod* nm); - static void log_sweep(const char* msg, const char* format = NULL, ...); static bool sweep_in_progress(); + static void sweep_code_cache(); + static void request_nmethod_marking() { _request_mark_phase = true; } + static void reset_nmethod_marking() { _request_mark_phase = false; } + static bool need_marking_phase() { return _request_mark_phase; } + + static int _hotness_counter_reset_val; public: static long traversal_count() { return _traversals; } - static int number_of_flushes() { return _number_of_flushes; } static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } static jlong total_time_sweeping() { return _total_time_sweeping; } static jlong peak_sweep_time() { return _peak_sweep_time; } static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } - static jlong total_disconnect_time() { return _total_disconnect_time; } - static jlong peak_disconnect_time() { return _peak_disconnect_time; } + static void log_sweep(const char* msg, const char* format = NULL, ...); + #ifdef ASSERT static bool is_sweeping(nmethod* which) { return _current == which; } @@ -90,19 +104,18 @@ static void report_events(); #endif - static void scan_stacks(); // Invoked at the end of each safepoint - static void sweep_code_cache(); // Concurrent part of sweep job - static void possibly_sweep(); // Compiler threads call this to sweep + static void mark_active_nmethods(); // Invoked at the end of each safepoint + static void possibly_sweep(); // Compiler threads call this to sweep - static void notify(nmethod* nm) { + static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2); + static int hotness_counter_reset_val(); + + static void notify() { // Request a new sweep of the code cache from the beginning. No // need to synchronize the setting of this flag since it only // changes to false at safepoint so we can never overwrite it with false. - _resweep = true; + request_nmethod_marking(); } - - static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate - static void speculative_disconnect_nmethods(bool was_full); // Called by vm op to deal with alloc failure }; #endif // SHARE_VM_RUNTIME_SWEEPER_HPP
--- a/src/share/vm/runtime/vmStructs.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/vmStructs.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -842,7 +842,7 @@ nonstatic_field(nmethod, _osr_link, nmethod*) \ nonstatic_field(nmethod, _scavenge_root_link, nmethod*) \ nonstatic_field(nmethod, _scavenge_root_state, jbyte) \ - nonstatic_field(nmethod, _state, unsigned char) \ + nonstatic_field(nmethod, _state, volatile unsigned char) \ nonstatic_field(nmethod, _exception_offset, int) \ nonstatic_field(nmethod, _deoptimize_offset, int) \ nonstatic_field(nmethod, _deoptimize_mh_offset, int) \ @@ -1360,6 +1360,7 @@ declare_integer_type(long) \ declare_integer_type(char) \ declare_unsigned_integer_type(unsigned char) \ + declare_unsigned_integer_type(volatile unsigned char) \ declare_unsigned_integer_type(u_char) \ declare_unsigned_integer_type(unsigned int) \ declare_unsigned_integer_type(uint) \ @@ -1382,6 +1383,7 @@ declare_toplevel_type(char**) \ declare_toplevel_type(u_char*) \ declare_toplevel_type(unsigned char*) \ + declare_toplevel_type(volatile unsigned char*) \ \ /*******************************************************************/ \ /* Types which it will be handy to have available over in the SA */ \
--- a/src/share/vm/runtime/vm_operations.cpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/vm_operations.cpp Fri Sep 27 15:43:03 2013 -0700 @@ -173,10 +173,6 @@ SymbolTable::unlink(); } -void VM_HandleFullCodeCache::doit() { - NMethodSweeper::speculative_disconnect_nmethods(_is_full); -} - void VM_Verify::doit() { Universe::heap()->prepare_for_verify(); Universe::verify(_silent);
--- a/src/share/vm/runtime/vm_operations.hpp Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/runtime/vm_operations.hpp Fri Sep 27 15:43:03 2013 -0700 @@ -51,7 +51,6 @@ template(DeoptimizeAll) \ template(ZombieAll) \ template(UnlinkSymbols) \ - template(HandleFullCodeCache) \ template(Verify) \ template(PrintJNI) \ template(HeapDumper) \ @@ -261,16 +260,6 @@ bool allow_nested_vm_operations() const { return true; } }; -class VM_HandleFullCodeCache: public VM_Operation { - private: - bool _is_full; - public: - VM_HandleFullCodeCache(bool is_full) { _is_full = is_full; } - VMOp_Type type() const { return VMOp_HandleFullCodeCache; } - void doit(); - bool allow_nested_vm_operations() const { return true; } -}; - #ifndef PRODUCT class VM_DeoptimizeAll: public VM_Operation { private:
--- a/src/share/vm/trace/trace.xml Fri Sep 27 12:43:51 2013 -0700 +++ b/src/share/vm/trace/trace.xml Fri Sep 27 15:43:03 2013 -0700 @@ -313,13 +313,6 @@ <value type="UINT" field="zombifiedCount" label="Methods Zombified"/> </event> - <event id="CleanCodeCache" path="vm/code_sweeper/clean" label="Clean Code Cache" - description="Clean code cache from oldest methods" - has_thread="true" is_requestable="false" is_constant="false"> - <value type="UINT" field="disconnectedCount" label="Methods Disconnected"/> - <value type="UINT" field="madeNonEntrantCount" label="Methods Made Non-Entrant"/> - </event> - <!-- Code cache events --> <event id="CodeCacheFull" path="vm/code_cache/full" label="Code Cache Full"