jdk8-mips64-public/hotspot: src/share/vm/runtime/sweeper.cpp@427b2fb1944f (annotated)

src/share/vm/runtime/sweeper.cpp@427b2fb1944f (annotated)

src/share/vm/runtime/sweeper.cpp

Wed, 31 Jan 2018 19:24:57 -0500

author: dbuck
date: Wed, 31 Jan 2018 19:24:57 -0500
changeset 9289: 427b2fb1944f
parent 8713: 8dfbb002197a
child 8856: ac27a9c85bea
child 9858: b985cbb00e68
permissions: -rw-r--r--

8189170: Add option to disable stack overflow checking in primordial thread for use with JNI_CreateJavaJVM
Reviewed-by: dcubed

 /*
  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "code/codeCache.hpp"
 #include "code/compiledIC.hpp"
 #include "code/icBuffer.hpp"
 #include "code/nmethod.hpp"
 #include "compiler/compileBroker.hpp"
 #include "memory/resourceArea.hpp"
 #include "oops/method.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/compilationPolicy.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/orderAccess.inline.hpp"
 #include "runtime/os.hpp"
 #include "runtime/sweeper.hpp"
 #include "runtime/thread.inline.hpp"
 #include "runtime/vm_operations.hpp"
 #include "trace/tracing.hpp"
 #include "utilities/events.hpp"
 #include "utilities/ticks.inline.hpp"
 #include "utilities/xmlstream.hpp"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 #ifdef ASSERT
 #define SWEEP(nm) record_sweep(nm, __LINE__)
 // Sweeper logging code
 class SweeperRecord {
  public:
   int traversal;
   int invocation;
   int compile_id;
   long traversal_mark;
   int state;
   const char* kind;
   address vep;
   address uep;
   int line;
   void print() {
       tty->print_cr("traversal = %d invocation = %d compile_id = %d %s uep = " PTR_FORMAT " vep = "
                     PTR_FORMAT " state = %d traversal_mark %d line = %d",
                     traversal,
                     invocation,
                     compile_id,
                     kind == NULL ? "" : kind,
                     uep,
                     vep,
                     state,
                     traversal_mark,
                     line);
   }
 };
 static int _sweep_index = 0;
 static SweeperRecord* _records = NULL;
 void NMethodSweeper::report_events(int id, address entry) {
   if (_records != NULL) {
     for (int i = _sweep_index; i < SweeperLogEntries; i++) {
       if (_records[i].uep == entry ||
           _records[i].vep == entry ||
           _records[i].compile_id == id) {
         _records[i].print();
       }
     }
     for (int i = 0; i < _sweep_index; i++) {
       if (_records[i].uep == entry ||
           _records[i].vep == entry ||
           _records[i].compile_id == id) {
         _records[i].print();
       }
     }
   }
 }
 void NMethodSweeper::report_events() {
   if (_records != NULL) {
     for (int i = _sweep_index; i < SweeperLogEntries; i++) {
       // skip empty records
       if (_records[i].vep == NULL) continue;
       _records[i].print();
     }
     for (int i = 0; i < _sweep_index; i++) {
       // skip empty records
       if (_records[i].vep == NULL) continue;
       _records[i].print();
     }
   }
 }
 void NMethodSweeper::record_sweep(nmethod* nm, int line) {
   if (_records != NULL) {
     _records[_sweep_index].traversal = _traversals;
     _records[_sweep_index].traversal_mark = nm->_stack_traversal_mark;
     _records[_sweep_index].invocation = _sweep_fractions_left;
     _records[_sweep_index].compile_id = nm->compile_id();
     _records[_sweep_index].kind = nm->compile_kind();
     _records[_sweep_index].state = nm->_state;
     _records[_sweep_index].vep = nm->verified_entry_point();
     _records[_sweep_index].uep = nm->entry_point();
     _records[_sweep_index].line = line;
     _sweep_index = (_sweep_index + 1) % SweeperLogEntries;
   }
 }
 #else
 #define SWEEP(nm)
 #endif
 nmethod* NMethodSweeper::_current                      = NULL; // Current nmethod
 long     NMethodSweeper::_traversals                   = 0;    // Stack scan count, also sweep ID.
 long     NMethodSweeper::_total_nof_code_cache_sweeps  = 0;    // Total number of full sweeps of the code cache
 long     NMethodSweeper::_time_counter                 = 0;    // Virtual time used to periodically invoke sweeper
 long     NMethodSweeper::_last_sweep                   = 0;    // Value of _time_counter when the last sweep happened
 int      NMethodSweeper::_seen                         = 0;    // Nof. nmethod 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_for_reclamation_count = 0;    // Nof. nmethods marked for reclaim in current sweep
 volatile bool NMethodSweeper::_should_sweep            = true; // Indicates if we should invoke the sweeper
 volatile int  NMethodSweeper::_sweep_fractions_left    = 0;    // Nof. invocations left until we are completed with this pass
 volatile int  NMethodSweeper::_sweep_started           = 0;    // Flag to control conc sweeper
 volatile int  NMethodSweeper::_bytes_changed           = 0;    // Counts the total nmethod size if the nmethod changed from:
                                                                //   1) alive       -> not_entrant
                                                                //   2) not_entrant -> zombie
                                                                //   3) zombie      -> marked_for_reclamation
 int    NMethodSweeper::_hotness_counter_reset_val       = 0;
 long   NMethodSweeper::_total_nof_methods_reclaimed     = 0;    // Accumulated nof methods flushed
 long   NMethodSweeper::_total_nof_c2_methods_reclaimed  = 0;    // Accumulated nof methods flushed
 size_t NMethodSweeper::_total_flushed_size              = 0;    // Total number of bytes flushed from the code cache
 Tickspan  NMethodSweeper::_total_time_sweeping;                 // Accumulated time sweeping
 Tickspan  NMethodSweeper::_total_time_this_sweep;               // Total time this sweep
 Tickspan  NMethodSweeper::_peak_sweep_time;                     // Peak time for a full sweep
 Tickspan  NMethodSweeper::_peak_sweep_fraction_time;            // Peak time sweeping one fraction
 class MarkActivationClosure: 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());
       // 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);
 }
 // 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 we do not want to reclaim not-entrant or zombie methods there is no need
   // to scan stacks
   if (!MethodFlushing) {
     return;
   }
   // Increase time so that we can estimate when to invoke the sweeper again.
   _time_counter++;
   // Check for restart
   assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid");
   if (!sweep_in_progress()) {
     _seen = 0;
     _sweep_fractions_left = NmethodSweepFraction;
     _current = CodeCache::first_nmethod();
     _traversals += 1;
     _total_time_this_sweep = Tickspan();
     if (PrintMethodFlushing) {
       tty->print_cr("### Sweep: stack traversal %d", _traversals);
     }
     Threads::nmethods_do(&mark_activation_closure);
   } else {
     // Only set hotness counter
     Threads::nmethods_do(&set_hotness_closure);
   }
   OrderAccess::storestore();
 }
 /**
  * This function invokes the sweeper if at least one of the three conditions is met:
  *    (1) The code cache is getting full
  *    (2) There are sufficient state changes in/since the last sweep.
  *    (3) We have not been sweeping for 'some time'
  */
 void NMethodSweeper::possibly_sweep() {
   assert(JavaThread::current()->thread_state() == _thread_in_vm, "must run in vm mode");
   // Only compiler threads are allowed to sweep
   if (!MethodFlushing || !sweep_in_progress() || !Thread::current()->is_Compiler_thread()) {
     return;
   }
   // If there was no state change while nmethod sweeping, 'should_sweep' will be false.
   // This is one of the two places where should_sweep can be set to true. The general
   // idea is as follows: If there is enough free space in the code cache, there is no
   // need to invoke the sweeper. The following formula (which determines whether to invoke
   // the sweeper or not) depends on the assumption that for larger ReservedCodeCacheSizes
   // we need less frequent sweeps than for smaller ReservedCodecCacheSizes. Furthermore,
   // the formula considers how much space in the code cache is currently used. Here are
   // some examples that will (hopefully) help in understanding.
   //
   // Small ReservedCodeCacheSizes:  (e.g., < 16M) We invoke the sweeper every time, since
   //                                              the result of the division is 0. This
   //                                              keeps the used code cache size small
   //                                              (important for embedded Java)
   // Large ReservedCodeCacheSize :  (e.g., 256M + code cache is 10% full). The formula
   //                                              computes: (256 / 16) - 1 = 15
   //                                              As a result, we invoke the sweeper after
   //                                              15 invocations of 'mark_active_nmethods.
   // Large ReservedCodeCacheSize:   (e.g., 256M + code Cache is 90% full). The formula
   //                                              computes: (256 / 16) - 10 = 6.
   if (!_should_sweep) {
     const int time_since_last_sweep = _time_counter - _last_sweep;
     // ReservedCodeCacheSize has an 'unsigned' type. We need a 'signed' type for max_wait_time,
     // since 'time_since_last_sweep' can be larger than 'max_wait_time'. If that happens using
     // an unsigned type would cause an underflow (wait_until_next_sweep becomes a large positive
     // value) that disables the intended periodic sweeps.
     const int max_wait_time = ReservedCodeCacheSize / (16 * M);
     double wait_until_next_sweep = max_wait_time - time_since_last_sweep - CodeCache::reverse_free_ratio();
     assert(wait_until_next_sweep <= (double)max_wait_time, "Calculation of code cache sweeper interval is incorrect");
     if ((wait_until_next_sweep <= 0.0) || !CompileBroker::should_compile_new_jobs()) {
       _should_sweep = true;
     }
   }
   if (_should_sweep && _sweep_fractions_left > 0) {
     // Only one thread at a time will sweep
     jint old = Atomic::cmpxchg( 1, &_sweep_started, 0 );
     if (old != 0) {
       return;
     }
 #ifdef ASSERT
     if (LogSweeper && _records == NULL) {
       // Create the ring buffer for the logging code
       _records = NEW_C_HEAP_ARRAY(SweeperRecord, SweeperLogEntries, mtGC);
       memset(_records, 0, sizeof(SweeperRecord) * SweeperLogEntries);
     }
 #endif
     if (_sweep_fractions_left > 0) {
       sweep_code_cache();
       _sweep_fractions_left--;
     }
     // We are done with sweeping the code cache once.
     if (_sweep_fractions_left == 0) {
       _total_nof_code_cache_sweeps++;
       _last_sweep = _time_counter;
       // Reset flag; temporarily disables sweeper
       _should_sweep = false;
       // If there was enough state change, 'possibly_enable_sweeper()'
       // sets '_should_sweep' to true
       possibly_enable_sweeper();
       // Reset _bytes_changed only if there was enough state change. _bytes_changed
       // can further increase by calls to 'report_state_change'.
       if (_should_sweep) {
         _bytes_changed = 0;
       }
     }
     // Release work, because another compiler thread could continue.
     OrderAccess::release_store((int*)&_sweep_started, 0);
   }
 }
 void NMethodSweeper::sweep_code_cache() {
   ResourceMark rm;
   Ticks sweep_start_counter = Ticks::now();
   _flushed_count                = 0;
   _zombified_count              = 0;
   _marked_for_reclamation_count = 0;
   if (PrintMethodFlushing && Verbose) {
     tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_nmethods(), _sweep_fractions_left);
   }
   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.
     _sweep_fractions_left = 1;
   }
   // We want to visit all nmethods after NmethodSweepFraction
   // invocations so divide the remaining number of nmethods by the
   // remaining number of invocations.  This is only an estimate since
   // the number of nmethods changes during the sweep so the final
   // stage must iterate until it there are no more nmethods.
   int todo = (CodeCache::nof_nmethods() - _seen) / _sweep_fractions_left;
   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);
     // The last invocation iterates until there are no more nmethods
     for (int i = 0; (i < todo || _sweep_fractions_left == 1) && _current != NULL; i++) {
       swept_count++;
       if (SafepointSynchronize::is_synchronizing()) { // Safepoint request
         if (PrintMethodFlushing && Verbose) {
           tty->print_cr("### Sweep at %d out of %d, invocation: %d, yielding to safepoint", _seen, CodeCache::nof_nmethods(), _sweep_fractions_left);
         }
         MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
         assert(Thread::current()->is_Java_thread(), "should be java thread");
         JavaThread* thread = (JavaThread*)Thread::current();
         ThreadBlockInVM tbivm(thread);
         thread->java_suspend_self();
       }
       // Since we will give up the CodeCache_lock, always skip ahead
       // to the next nmethod.  Other blobs can be deleted by other
       // threads but nmethods are only reclaimed by the sweeper.
       nmethod* next = CodeCache::next_nmethod(_current);
       // Now ready to process nmethod and give up CodeCache_lock
       {
         MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
         freed_memory += process_nmethod(_current);
       }
       _seen++;
       _current = next;
     }
   }
   assert(_sweep_fractions_left > 1 || _current == NULL, "must have scanned the whole cache");
   const Ticks sweep_end_counter = Ticks::now();
   const Tickspan sweep_time = sweep_end_counter - sweep_start_counter;
   _total_time_sweeping  += sweep_time;
   _total_time_this_sweep += sweep_time;
   _peak_sweep_fraction_time = MAX2(sweep_time, _peak_sweep_fraction_time);
   _total_flushed_size += freed_memory;
   _total_nof_methods_reclaimed += _flushed_count;
   EventSweepCodeCache event(UNTIMED);
   if (event.should_commit()) {
     event.set_starttime(sweep_start_counter);
     event.set_endtime(sweep_end_counter);
     event.set_sweepIndex(_traversals);
     event.set_sweepFractionIndex(NmethodSweepFraction - _sweep_fractions_left + 1);
     event.set_sweptCount(swept_count);
     event.set_flushedCount(_flushed_count);
     event.set_markedCount(_marked_for_reclamation_count);
     event.set_zombifiedCount(_zombified_count);
     event.commit();
   }
 #ifdef ASSERT
   if(PrintMethodFlushing) {
     tty->print_cr("### sweeper:      sweep time(%d): "
       INT64_FORMAT, _sweep_fractions_left, (jlong)sweep_time.value());
   }
 #endif
   if (_sweep_fractions_left == 1) {
     _peak_sweep_time = MAX2(_peak_sweep_time, _total_time_this_sweep);
     log_sweep("finished");
   }
   // 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 (!CompileBroker::should_compile_new_jobs() && (freed_memory > 0)) {
     CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation);
     log_sweep("restart_compiler");
   }
 }
 /**
  * This function updates the sweeper statistics that keep track of nmethods
  * state changes. If there is 'enough' state change, the sweeper is invoked
  * as soon as possible. There can be data races on _bytes_changed. The data
  * races are benign, since it does not matter if we loose a couple of bytes.
  * In the worst case we call the sweeper a little later. Also, we are guaranteed
  * to invoke the sweeper if the code cache gets full.
  */
 void NMethodSweeper::report_state_change(nmethod* nm) {
   _bytes_changed += nm->total_size();
   possibly_enable_sweeper();
 }
 /**
  * Function determines if there was 'enough' state change in the code cache to invoke
  * the sweeper again. Currently, we determine 'enough' as more than 1% state change in
  * the code cache since the last sweep.
  */
 void NMethodSweeper::possibly_enable_sweeper() {
   double percent_changed = ((double)_bytes_changed / (double)ReservedCodeCacheSize) * 100;
   if (percent_changed > 1.0) {
     _should_sweep = true;
   }
 }
 class NMethodMarker: public StackObj {
  private:
   CompilerThread* _thread;
  public:
   NMethodMarker(nmethod* nm) {
     _thread = CompilerThread::current();
     if (!nm->is_zombie() && !nm->is_unloaded()) {
       // Only expose live nmethods for scanning
       _thread->set_scanned_nmethod(nm);
     }
   }
   ~NMethodMarker() {
     _thread->set_scanned_nmethod(NULL);
   }
 };
 void NMethodSweeper::release_nmethod(nmethod *nm) {
   // Clean up any CompiledICHolders
   {
     ResourceMark rm;
     MutexLocker ml_patch(CompiledIC_lock);
     RelocIterator iter(nm);
     while (iter.next()) {
       if (iter.type() == relocInfo::virtual_call_type) {
         CompiledIC::cleanup_call_site(iter.virtual_call_reloc());
       }
     }
   }
   MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
   nm->flush();
 }
 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 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 inline caches that point to zombie/non-entrant methods
       MutexLocker cl(CompiledIC_lock);
       nm->cleanup_inline_caches();
       SWEEP(nm);
     }
     return freed_memory;
   }
   if (nm->is_zombie()) {
     // 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();
       if (nm->is_compiled_by_c2()) {
         _total_nof_c2_methods_reclaimed++;
       }
       release_nmethod(nm);
       _flushed_count++;
     } else {
       if (PrintMethodFlushing && Verbose) {
         tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm);
       }
       nm->mark_for_reclamation();
       // Keep track of code cache state change
       _bytes_changed += nm->total_size();
       _marked_for_reclamation_count++;
       SWEEP(nm);
     }
   } else if (nm->is_not_entrant()) {
     // If there are no current activations of this method on the
     // stack we can safely convert it to a zombie method
     if (nm->can_convert_to_zombie()) {
       if (PrintMethodFlushing && Verbose) {
         tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm);
       }
       // Clear ICStubs to prevent back patching stubs of zombie or unloaded
       // nmethods during the next safepoint (see ICStub::finalize).
       MutexLocker cl(CompiledIC_lock);
       nm->clear_ic_stubs();
       // Code cache state change is tracked in make_zombie()
       nm->make_zombie();
       _zombified_count++;
       SWEEP(nm);
     } else {
       // Still alive, clean up its inline caches
       MutexLocker cl(CompiledIC_lock);
       nm->cleanup_inline_caches();
       SWEEP(nm);
     }
   } else if (nm->is_unloaded()) {
     // Unloaded code, just make it a zombie
     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();
       if (nm->is_compiled_by_c2()) {
         _total_nof_c2_methods_reclaimed++;
       }
       release_nmethod(nm);
       _flushed_count++;
     } else {
       {
         // Clean ICs of unloaded nmethods as well because they may reference other
         // unloaded nmethods that may be flushed earlier in the sweeper cycle.
         MutexLocker cl(CompiledIC_lock);
         nm->cleanup_inline_caches();
       }
       // Code cache state change is tracked in make_zombie()
       nm->make_zombie();
       _zombified_count++;
       SWEEP(nm);
     }
   } else {
     if (UseCodeCacheFlushing) {
       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();
           // Code cache state change is tracked in make_not_entrant()
           if (PrintMethodFlushing && Verbose) {
             tty->print_cr("### Nmethod %d/" PTR_FORMAT "made not-entrant: hotness counter %d/%d threshold %f",
                           nm->compile_id(), nm, nm->hotness_counter(), reset_val, threshold);
           }
         }
       }
     }
     // Clean-up all inline caches that point to zombie/non-reentrant methods
     MutexLocker cl(CompiledIC_lock);
     nm->cleanup_inline_caches();
     SWEEP(nm);
   }
   return freed_memory;
 }
 // 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, ...) {
   if (PrintMethodFlushing) {
     ResourceMark rm;
     stringStream s;
     // Dump code cache state into a buffer before locking the tty,
     // because log_state() will use locks causing lock conflicts.
     CodeCache::log_state(&s);
     ttyLocker ttyl;
     tty->print("### sweeper: %s ", msg);
     if (format != NULL) {
       va_list ap;
       va_start(ap, format);
       tty->vprint(format, ap);
       va_end(ap);
     }
     tty->print_cr("%s", s.as_string());
   }
   if (LogCompilation && (xtty != NULL)) {
     ResourceMark rm;
     stringStream s;
     // Dump code cache state into a buffer before locking the tty,
     // because log_state() will use locks causing lock conflicts.
     CodeCache::log_state(&s);
     ttyLocker ttyl;
     xtty->begin_elem("sweeper state='%s' traversals='" INTX_FORMAT "' ", msg, (intx)traversal_count());
     if (format != NULL) {
       va_list ap;
       va_start(ap, format);
       xtty->vprint(format, ap);
       va_end(ap);
     }
     xtty->print("%s", s.as_string());
     xtty->stamp();
     xtty->end_elem();
   }
 }
 void NMethodSweeper::print() {
   ttyLocker ttyl;
   tty->print_cr("Code cache sweeper statistics:");
   tty->print_cr("  Total sweep time:                %1.0lfms", (double)_total_time_sweeping.value()/1000000);
   tty->print_cr("  Total number of full sweeps:     %ld", _total_nof_code_cache_sweeps);
   tty->print_cr("  Total number of flushed methods: %ld(%ld C2 methods)", _total_nof_methods_reclaimed,
                                                     _total_nof_c2_methods_reclaimed);
   tty->print_cr("  Total size of flushed methods:   " SIZE_FORMAT "kB", _total_flushed_size/K);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/runtime/sweeper.cpp@427b2fb1944f (annotated)

src/share/vm/runtime/sweeper.cpp