jdk8-mips64-public/hotspot: src/share/vm/runtime/sweeper.cpp@5f24d0319e54 (annotated)

src/share/vm/runtime/sweeper.cpp@5f24d0319e54 (annotated)

src/share/vm/runtime/sweeper.cpp

Fri, 29 Jan 2010 09:27:22 -0800

author: kvn
date: Fri, 29 Jan 2010 09:27:22 -0800
changeset 1637: 5f24d0319e54
parent 1435: a1423fe86a18
child 1893: bfe29ec02863
permissions: -rw-r--r--

4360113: Evict nmethods when code cache gets full
Summary: Speculatively unload the oldest nmethods when code cache gets full.
Reviewed-by: never, kvn
Contributed-by: eric.caspole@amd.com

 /*
  * Copyright 1997-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_sweeper.cpp.incl"
 long      NMethodSweeper::_traversals = 0;   // No. of stack traversals performed
 CodeBlob* NMethodSweeper::_current = NULL;   // Current nmethod
 int       NMethodSweeper::_seen = 0 ;        // No. of blobs we have currently processed in current pass of CodeCache
 int       NMethodSweeper::_invocations = 0;  // No. of invocations left until we are completed with this pass
 jint      NMethodSweeper::_locked_seen = 0;
 jint      NMethodSweeper::_not_entrant_seen_on_stack = 0;
 bool      NMethodSweeper::_rescan = false;
 bool      NMethodSweeper::_was_full = false;
 jint      NMethodSweeper::_advise_to_sweep = 0;
 jlong     NMethodSweeper::_last_was_full = 0;
 uint      NMethodSweeper::_highest_marked = 0;
 long      NMethodSweeper::_was_full_traversal = 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();
     }
   }
 };
 static MarkActivationClosure mark_activation_closure;
 void NMethodSweeper::sweep() {
   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.  If we aren't in the middle of scan and a rescan
   // hasn't been requested then just return.
   if (_current == NULL && !_rescan) return;
   // 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;
   // Check for restart
   assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid");
   if (_current == NULL) {
     _seen        = 0;
     _invocations = NmethodSweepFraction;
     _current     = CodeCache::first();
     _traversals  += 1;
     if (PrintMethodFlushing) {
       tty->print_cr("### Sweep: stack traversal %d", _traversals);
     }
     Threads::nmethods_do(&mark_activation_closure);
     // reset the flags since we started a scan from the beginning.
     _rescan = false;
     _locked_seen = 0;
     _not_entrant_seen_on_stack = 0;
   }
   if (PrintMethodFlushing && Verbose) {
     tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_blobs(), _invocations);
   }
   // We want to visit all nmethods after NmethodSweepFraction invocations.
   // If invocation is 1 we do the rest
   int todo = CodeCache::nof_blobs();
   if (_invocations != 1) {
     todo = (CodeCache::nof_blobs() - _seen) / _invocations;
     _invocations--;
   }
   for(int i = 0; i < todo && _current != NULL; i++) {
     CodeBlob* next = CodeCache::next(_current); // Read next before we potentially delete current
     if (_current->is_nmethod()) {
       process_nmethod((nmethod *)_current);
     }
     _seen++;
     _current = next;
   }
   // Because we could stop on a codeBlob other than an nmethod we skip forward
   // to the next nmethod (if any). codeBlobs other than nmethods can be freed
   // async to us and make _current invalid while we sleep.
   while (_current != NULL && !_current->is_nmethod()) {
     _current = CodeCache::next(_current);
   }
   if (_current == NULL && !_rescan && (_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
     // but that complicates the control logic and it's unlikely to
     // matter much.
     if (PrintMethodFlushing) {
       tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep");
     }
   }
   if (UseCodeCacheFlushing) {
     if (!CodeCache::needs_flushing()) {
       // In a safepoint, no race with setters
       _advise_to_sweep = 0;
     }
     if (was_full()) {
       // There was some progress so attempt to restart the compiler
       jlong now           = os::javaTimeMillis();
       jlong max_interval  = (jlong)MinCodeCacheFlushingInterval * (jlong)1000;
       jlong curr_interval = now - _last_was_full;
       if ((!CodeCache::needs_flushing()) && (curr_interval > max_interval)) {
         CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation);
         set_was_full(false);
         // Update the _last_was_full time so we can tell how fast the
         // code cache is filling up
         _last_was_full = os::javaTimeMillis();
         if (PrintMethodFlushing) {
           tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler",
             CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
         }
         if (LogCompilation && (xtty != NULL)) {
           ttyLocker ttyl;
           xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
                            CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
           xtty->stamp();
           xtty->end_elem();
         }
       }
     }
   }
 }
 void NMethodSweeper::process_nmethod(nmethod *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
       nm->cleanup_inline_caches();
     } else {
       _locked_seen++;
     }
     return;
   }
   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
     // there are no inline caches that referes 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);
       }
       nm->flush();
     } else {
       if (PrintMethodFlushing && Verbose) {
         tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm);
       }
       nm->mark_for_reclamation();
       _rescan = true;
     }
   } else if (nm->is_not_entrant()) {
     // If there is 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();
       _rescan = true;
     } else {
       // Still alive, clean up its inline caches
       nm->cleanup_inline_caches();
       // we coudn't transition this nmethod so don't immediately
       // request a rescan.  If this method stays on the stack for a
       // long time we don't want to keep rescanning at every safepoint.
       _not_entrant_seen_on_stack++;
     }
   } 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()) {
       // No inline caches will ever point to osr methods, so we can just remove it
       nm->flush();
     } else {
       nm->make_zombie();
       _rescan = true;
     }
   } else {
     assert(nm->is_alive(), "should be alive");
     if (UseCodeCacheFlushing) {
       if ((nm->method()->code() != nm) && !(nm->is_locked_by_vm()) && !(nm->is_osr_method()) &&
           (_traversals > _was_full_traversal+2) && (((uint)nm->compile_id()) < _highest_marked) &&
           CodeCache::needs_flushing()) {
         // This method has not been called since the forced cleanup happened
         nm->make_not_entrant();
       }
     }
     // Clean-up all inline caches that points to zombie/non-reentrant methods
     nm->cleanup_inline_caches();
   }
 }
 // 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
 // safepoint from the current one, the nmethod will be marked non-entrant and
 // got rid of by normal sweeping. If the method is called, the methodOop's
 // _code field is restored and the methodOop/nmethod
 // go back to their normal state.
 void NMethodSweeper::handle_full_code_cache(bool is_full) {
   // Only the first one to notice can advise us to start early cleaning
   if (!is_full){
     jint old = Atomic::cmpxchg( 1, &_advise_to_sweep, 0 );
     if (old != 0) {
       return;
     }
   }
   if (is_full) {
     // Since code cache is full, immediately stop new compiles
     bool did_set = CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation);
     if (!did_set) {
       // only the first to notice can start the cleaning,
       // others will go back and block
       return;
     }
     set_was_full(true);
     // If we run out within MinCodeCacheFlushingInterval of the last unload time, give up
     jlong now = os::javaTimeMillis();
     jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000;
     jlong curr_interval = now - _last_was_full;
     if (curr_interval < max_interval) {
       _rescan = true;
       if (PrintMethodFlushing) {
         tty->print_cr("### handle full too often, turning off compiler");
       }
       if (LogCompilation && (xtty != NULL)) {
         ttyLocker ttyl;
         xtty->begin_elem("disable_compiler flushing_interval='" UINT64_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
                          curr_interval/1000, CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
         xtty->stamp();
         xtty->end_elem();
       }
       return;
     }
   }
   VM_HandleFullCodeCache op(is_full);
   VMThread::execute(&op);
   // rescan again as soon as possible
   _rescan = true;
 }
 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
   debug_only(jlong start = os::javaTimeMillis();)
   if ((!was_full()) && (is_full)) {
     if (!CodeCache::needs_flushing()) {
       if (PrintMethodFlushing) {
         tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler",
           CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
       }
       if (LogCompilation && (xtty != NULL)) {
         ttyLocker ttyl;
         xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
                          CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
         xtty->stamp();
         xtty->end_elem();
       }
       CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation);
       return;
     }
   }
   // Traverse the code cache trying to dump the oldest nmethods
   uint curr_max_comp_id = CompileBroker::get_compilation_id();
   uint flush_target = ((curr_max_comp_id - _highest_marked) >> 1) + _highest_marked;
   if (PrintMethodFlushing && Verbose) {
     tty->print_cr("### Cleaning code cache: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes",
         CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
   }
   if (LogCompilation && (xtty != NULL)) {
     ttyLocker ttyl;
     xtty->begin_elem("start_cleaning_code_cache live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
                       CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
     xtty->stamp();
     xtty->end_elem();
   }
   nmethod* nm = CodeCache::alive_nmethod(CodeCache::first());
   jint disconnected = 0;
   jint made_not_entrant  = 0;
   while ((nm != NULL)){
     uint 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_in_use() && (!nm->is_osr_method()) && (!nm->is_locked_by_vm()) &&
         (!nm->is_native_method()) && ((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
         nm->method()->invocation_counter()->decay();
         nm->method()->backedge_counter()->decay();
         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));
   }
   if (LogCompilation && (xtty != NULL)) {
     ttyLocker ttyl;
     xtty->begin_elem("stop_cleaning_code_cache disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
                       disconnected, made_not_entrant, CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
     xtty->stamp();
     xtty->end_elem();
   }
   // Shut off compiler. Sweeper will run exiting from this safepoint
   // and turn it back on if it clears enough space
   if (was_full()) {
     _last_was_full = os::javaTimeMillis();
     CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation);
   }
   // After two more traversals the sweeper will get rid of unrestored nmethods
   _was_full_traversal = _traversals;
 #ifdef ASSERT
   jlong end = os::javaTimeMillis();
   if(PrintMethodFlushing && Verbose) {
     tty->print_cr("### sweeper: unload time: " INT64_FORMAT, end-start);
   }
 #endif
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/runtime/sweeper.cpp@5f24d0319e54 (annotated)

src/share/vm/runtime/sweeper.cpp