Fri, 27 Sep 2013 10:50:55 +0200
8020151: PSR:PERF Large performance regressions when code cache is filled
Summary: Code cache sweeping based on method hotness; removed speculatively disconnect
Reviewed-by: kvn, iveresov
duke@435 | 1 | /* |
sla@5237 | 2 | * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
trims@1907 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
trims@1907 | 20 | * or visit www.oracle.com if you need additional information or have any |
trims@1907 | 21 | * questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
stefank@2314 | 25 | #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP |
stefank@2314 | 26 | #define SHARE_VM_RUNTIME_SWEEPER_HPP |
stefank@2314 | 27 | |
duke@435 | 28 | // An NmethodSweeper is an incremental cleaner for: |
duke@435 | 29 | // - cleanup inline caches |
anoll@5792 | 30 | // - reclamation of nmethods |
anoll@5792 | 31 | // Removing nmethods from the code cache includes two operations |
anoll@5792 | 32 | // 1) mark active nmethods |
anoll@5792 | 33 | // Is done in 'mark_active_nmethods()'. This function is called at a |
anoll@5792 | 34 | // safepoint and marks all nmethods that are active on a thread's stack. |
anoll@5792 | 35 | // 2) sweep nmethods |
anoll@5792 | 36 | // Is done in sweep_code_cache(). This function is the only place in the |
anoll@5792 | 37 | // sweeper where memory is reclaimed. Note that sweep_code_cache() is not |
anoll@5792 | 38 | // called at a safepoint. However, sweep_code_cache() stops executing if |
anoll@5792 | 39 | // another thread requests a safepoint. Consequently, 'mark_active_nmethods()' |
anoll@5792 | 40 | // and sweep_code_cache() cannot execute at the same time. |
anoll@5792 | 41 | // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can |
anoll@5792 | 42 | // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency |
anoll@5792 | 43 | // invalidation, and (iv) being replaced be a different method version (tiered |
anoll@5792 | 44 | // compilation). Not-entrant nmethod cannot be called by Java threads, but they |
anoll@5792 | 45 | // can still be active on the stack. To ensure that active nmethod are not reclaimed, |
anoll@5792 | 46 | // we have to wait until the next marking phase has completed. If a not-entrant |
anoll@5792 | 47 | // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely |
anoll@5792 | 48 | // remove the nmethod, all inline caches (IC) that point to the the nmethod must be |
anoll@5792 | 49 | // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's |
anoll@5792 | 50 | // state change happens during separate sweeps. It may take at least 3 sweeps before an |
anoll@5792 | 51 | // nmethod's space is freed. Sweeping is currently done by compiler threads between |
anoll@5792 | 52 | // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache |
anoll@5792 | 53 | // is full. |
duke@435 | 54 | |
duke@435 | 55 | class NMethodSweeper : public AllStatic { |
sla@5237 | 56 | static long _traversals; // Stack scan count, also sweep ID. |
sla@5237 | 57 | static nmethod* _current; // Current nmethod |
sla@5237 | 58 | static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache |
sla@5237 | 59 | static int _flushed_count; // Nof. nmethods flushed in current sweep |
sla@5237 | 60 | static int _zombified_count; // Nof. nmethods made zombie in current sweep |
sla@5237 | 61 | static int _marked_count; // Nof. nmethods marked for reclaim in current sweep |
never@1999 | 62 | |
neliasso@5038 | 63 | static volatile int _invocations; // No. of invocations left until we are completed with this pass |
neliasso@5038 | 64 | static volatile int _sweep_started; // Flag to control conc sweeper |
duke@435 | 65 | |
anoll@5792 | 66 | //The following are reset in mark_active_nmethods and synchronized by the safepoint |
anoll@5792 | 67 | static bool _request_mark_phase; // Indicates that a change has happend and we need another mark pahse, |
anoll@5792 | 68 | // always checked and reset at a safepoint so memory will be in sync. |
anoll@5792 | 69 | static int _locked_seen; // Number of locked nmethods encountered during the scan |
duke@435 | 70 | static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack |
duke@435 | 71 | |
sla@5237 | 72 | // Stat counters |
sla@5237 | 73 | static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed |
sla@5237 | 74 | static jlong _total_time_sweeping; // Accumulated time sweeping |
sla@5237 | 75 | static jlong _total_time_this_sweep; // Total time this sweep |
sla@5237 | 76 | static jlong _peak_sweep_time; // Peak time for a full sweep |
sla@5237 | 77 | static jlong _peak_sweep_fraction_time; // Peak time sweeping one fraction |
sla@5237 | 78 | |
anoll@5792 | 79 | static int process_nmethod(nmethod *nm); |
coleenp@4037 | 80 | static void release_nmethod(nmethod* nm); |
coleenp@4037 | 81 | |
neliasso@5038 | 82 | static bool sweep_in_progress(); |
anoll@5792 | 83 | static void sweep_code_cache(); |
anoll@5792 | 84 | static void request_nmethod_marking() { _request_mark_phase = true; } |
anoll@5792 | 85 | static void reset_nmethod_marking() { _request_mark_phase = false; } |
anoll@5792 | 86 | static bool need_marking_phase() { return _request_mark_phase; } |
anoll@5792 | 87 | |
anoll@5792 | 88 | static int _hotness_counter_reset_val; |
never@1999 | 89 | |
duke@435 | 90 | public: |
sla@5237 | 91 | static long traversal_count() { return _traversals; } |
sla@5237 | 92 | static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } |
sla@5237 | 93 | static jlong total_time_sweeping() { return _total_time_sweeping; } |
sla@5237 | 94 | static jlong peak_sweep_time() { return _peak_sweep_time; } |
sla@5237 | 95 | static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } |
anoll@5792 | 96 | static void log_sweep(const char* msg, const char* format = NULL, ...); |
anoll@5792 | 97 | |
duke@435 | 98 | |
never@2916 | 99 | #ifdef ASSERT |
johnc@5548 | 100 | static bool is_sweeping(nmethod* which) { return _current == which; } |
never@2916 | 101 | // Keep track of sweeper activity in the ring buffer |
never@2916 | 102 | static void record_sweep(nmethod* nm, int line); |
never@2916 | 103 | static void report_events(int id, address entry); |
never@2916 | 104 | static void report_events(); |
never@2916 | 105 | #endif |
never@2916 | 106 | |
anoll@5792 | 107 | static void mark_active_nmethods(); // Invoked at the end of each safepoint |
anoll@5792 | 108 | static void possibly_sweep(); // Compiler threads call this to sweep |
duke@435 | 109 | |
anoll@5792 | 110 | static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2); |
anoll@5792 | 111 | static int hotness_counter_reset_val(); |
anoll@5792 | 112 | |
anoll@5792 | 113 | static void notify() { |
neliasso@5038 | 114 | // Request a new sweep of the code cache from the beginning. No |
duke@435 | 115 | // need to synchronize the setting of this flag since it only |
duke@435 | 116 | // changes to false at safepoint so we can never overwrite it with false. |
anoll@5792 | 117 | request_nmethod_marking(); |
duke@435 | 118 | } |
duke@435 | 119 | }; |
stefank@2314 | 120 | |
stefank@2314 | 121 | #endif // SHARE_VM_RUNTIME_SWEEPER_HPP |