Mercurial > hg > truffle
view src/os_cpu/solaris_sparc/vm/threadLS_solaris_sparc.hpp @ 453:c96030fff130
6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa
author | ysr |
---|---|
date | Thu, 20 Nov 2008 16:56:09 -0800 |
parents | a61af66fc99e |
children | c18cbe5936b8 |
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/* * Copyright 1998-2005 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. * */ public: // Java Thread - force inlining static inline Thread* thread() ; private: static Thread* _get_thread_cache[]; // index by [(raw_id>>9)^(raw_id>>20) % _pd_cache_size] static Thread* get_thread_via_cache_slowly(uintptr_t raw_id, int index); NOT_PRODUCT(static int _tcacheHit;) NOT_PRODUCT(static int _tcacheMiss;) public: // Print cache hit/miss statistics static void print_statistics() PRODUCT_RETURN; enum Constants { _pd_cache_size = 256*2 // projected typical # of threads * 2 }; static void set_thread_in_slot (Thread *) ; static uintptr_t pd_raw_thread_id() { return _raw_thread_id(); } static int pd_cache_index(uintptr_t raw_id) { // Hash function: From email from Dave: // The hash function deserves an explanation. %g7 points to libthread's // "thread" structure. On T1 the thread structure is allocated on the // user's stack (yes, really!) so the ">>20" handles T1 where the JVM's // stack size is usually >= 1Mb. The ">>9" is for T2 where Roger allocates // globs of thread blocks contiguously. The "9" has to do with the // expected size of the T2 thread structure. If these constants are wrong // the worst thing that'll happen is that the hit rate for heavily threaded // apps won't be as good as it could be. If you want to burn another // shift+xor you could mix together _all of the %g7 bits to form the hash, // but I think that's excessive. Making the change above changed the // T$ miss rate on SpecJBB (on a 16X system) from about 3% to imperceptible. uintptr_t ix = (int) (((raw_id >> 9) ^ (raw_id >> 20)) % _pd_cache_size); return ix; }