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src/share/vm/gc_implementation/shared/allocationStats.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/shared/allocationStats.hpp

Tue, 13 Apr 2010 13:52:10 -0700

author

jmasa

date

Tue, 13 Apr 2010 13:52:10 -0700

changeset 1822

0bfd3fb24150

parent 1580

e018e6884bd8

child 1907

c18cbe5936b8

permissions

-rw-r--r--

6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes

duke@435	1	/*
xdono@631	2	* Copyright 2001-2008 Sun Microsystems, Inc. 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	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	class AllocationStats VALUE_OBJ_CLASS_SPEC {
duke@435	26	// A duration threshold (in ms) used to filter
duke@435	27	// possibly unreliable samples.
duke@435	28	static float _threshold;
duke@435	29
duke@435	30	// We measure the demand between the end of the previous sweep and
duke@435	31	// beginning of this sweep:
duke@435	32	// Count(end_last_sweep) - Count(start_this_sweep)
duke@435	33	// + splitBirths(between) - splitDeaths(between)
ysr@1580	34	// The above number divided by the time since the end of the
duke@435	35	// previous sweep gives us a time rate of demand for blocks
duke@435	36	// of this size. We compute a padded average of this rate as
duke@435	37	// our current estimate for the time rate of demand for blocks
duke@435	38	// of this size. Similarly, we keep a padded average for the time
duke@435	39	// between sweeps. Our current estimate for demand for blocks of
duke@435	40	// this size is then simply computed as the product of these two
duke@435	41	// estimates.
duke@435	42	AdaptivePaddedAverage _demand_rate_estimate;
duke@435	43
ysr@1580	44	ssize_t _desired; // Demand stimate computed as described above
duke@435	45	ssize_t _coalDesired; // desired +/- small-percent for tuning coalescing
duke@435	46
duke@435	47	ssize_t _surplus; // count - (desired +/- small-percent),
duke@435	48	// used to tune splitting in best fit
duke@435	49	ssize_t _bfrSurp; // surplus at start of current sweep
duke@435	50	ssize_t _prevSweep; // count from end of previous sweep
duke@435	51	ssize_t _beforeSweep; // count from before current sweep
duke@435	52	ssize_t _coalBirths; // additional chunks from coalescing
duke@435	53	ssize_t _coalDeaths; // loss from coalescing
duke@435	54	ssize_t _splitBirths; // additional chunks from splitting
duke@435	55	ssize_t _splitDeaths; // loss from splitting
ysr@1580	56	size_t _returnedBytes; // number of bytes returned to list.
duke@435	57	public:
ysr@1580	58	void initialize(bool split_birth = false) {
duke@435	59	AdaptivePaddedAverage* dummy =
duke@435	60	new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight,
duke@435	61	CMS_FLSPadding);
duke@435	62	_desired = 0;
duke@435	63	_coalDesired = 0;
duke@435	64	_surplus = 0;
duke@435	65	_bfrSurp = 0;
duke@435	66	_prevSweep = 0;
duke@435	67	_beforeSweep = 0;
duke@435	68	_coalBirths = 0;
duke@435	69	_coalDeaths = 0;
ysr@1580	70	_splitBirths = split_birth? 1 : 0;
duke@435	71	_splitDeaths = 0;
duke@435	72	_returnedBytes = 0;
duke@435	73	}
duke@435	74
duke@435	75	AllocationStats() {
duke@435	76	initialize();
duke@435	77	}
ysr@1580	78
duke@435	79	// The rate estimate is in blocks per second.
duke@435	80	void compute_desired(size_t count,
duke@435	81	float inter_sweep_current,
ysr@1580	82	float inter_sweep_estimate,
ysr@1580	83	float intra_sweep_estimate) {
duke@435	84	// If the latest inter-sweep time is below our granularity
duke@435	85	// of measurement, we may call in here with
duke@435	86	// inter_sweep_current == 0. However, even for suitably small
duke@435	87	// but non-zero inter-sweep durations, we may not trust the accuracy
duke@435	88	// of accumulated data, since it has not been "integrated"
duke@435	89	// (read "low-pass-filtered") long enough, and would be
duke@435	90	// vulnerable to noisy glitches. In such cases, we
duke@435	91	// ignore the current sample and use currently available
duke@435	92	// historical estimates.
ysr@1580	93	// XXX NEEDS TO BE FIXED
ysr@1580	94	// assert(prevSweep() + splitBirths() >= splitDeaths() + (ssize_t)count, "Conservation Principle");
ysr@1580	95	// ^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ysr@1580	96	// "Total Stock" "Not used at this block size"
duke@435	97	if (inter_sweep_current > _threshold) {
ysr@1580	98	ssize_t demand = prevSweep() - (ssize_t)count + splitBirths() - splitDeaths();
ysr@1580	99	// XXX NEEDS TO BE FIXED
ysr@1580	100	// assert(demand >= 0, "Demand should be non-negative");
ysr@1580	101	// Defensive: adjust for imprecision in event counting
ysr@1580	102	if (demand < 0) {
ysr@1580	103	demand = 0;
ysr@1580	104	}
ysr@1580	105	float old_rate = _demand_rate_estimate.padded_average();
duke@435	106	float rate = ((float)demand)/inter_sweep_current;
duke@435	107	_demand_rate_estimate.sample(rate);
ysr@1580	108	float new_rate = _demand_rate_estimate.padded_average();
ysr@1580	109	ssize_t old_desired = _desired;
ysr@1580	110	_desired = (ssize_t)(new_rate * (inter_sweep_estimate
ysr@1580	111	+ CMSExtrapolateSweep
ysr@1580	112	? intra_sweep_estimate
ysr@1580	113	: 0.0));
ysr@1580	114	if (PrintFLSStatistics > 1) {
ysr@1580	115	gclog_or_tty->print_cr("demand: %d, old_rate: %f, current_rate: %f, new_rate: %f, old_desired: %d, new_desired: %d",
ysr@1580	116	demand, old_rate, rate, new_rate, old_desired, _desired);
ysr@1580	117	}
duke@435	118	}
duke@435	119	}
duke@435	120
duke@435	121	ssize_t desired() const { return _desired; }
ysr@447	122	void set_desired(ssize_t v) { _desired = v; }
ysr@447	123
duke@435	124	ssize_t coalDesired() const { return _coalDesired; }
duke@435	125	void set_coalDesired(ssize_t v) { _coalDesired = v; }
duke@435	126
duke@435	127	ssize_t surplus() const { return _surplus; }
duke@435	128	void set_surplus(ssize_t v) { _surplus = v; }
duke@435	129	void increment_surplus() { _surplus++; }
duke@435	130	void decrement_surplus() { _surplus--; }
duke@435	131
duke@435	132	ssize_t bfrSurp() const { return _bfrSurp; }
duke@435	133	void set_bfrSurp(ssize_t v) { _bfrSurp = v; }
duke@435	134	ssize_t prevSweep() const { return _prevSweep; }
duke@435	135	void set_prevSweep(ssize_t v) { _prevSweep = v; }
duke@435	136	ssize_t beforeSweep() const { return _beforeSweep; }
duke@435	137	void set_beforeSweep(ssize_t v) { _beforeSweep = v; }
duke@435	138
duke@435	139	ssize_t coalBirths() const { return _coalBirths; }
duke@435	140	void set_coalBirths(ssize_t v) { _coalBirths = v; }
duke@435	141	void increment_coalBirths() { _coalBirths++; }
duke@435	142
duke@435	143	ssize_t coalDeaths() const { return _coalDeaths; }
duke@435	144	void set_coalDeaths(ssize_t v) { _coalDeaths = v; }
duke@435	145	void increment_coalDeaths() { _coalDeaths++; }
duke@435	146
duke@435	147	ssize_t splitBirths() const { return _splitBirths; }
duke@435	148	void set_splitBirths(ssize_t v) { _splitBirths = v; }
duke@435	149	void increment_splitBirths() { _splitBirths++; }
duke@435	150
duke@435	151	ssize_t splitDeaths() const { return _splitDeaths; }
duke@435	152	void set_splitDeaths(ssize_t v) { _splitDeaths = v; }
duke@435	153	void increment_splitDeaths() { _splitDeaths++; }
duke@435	154
duke@435	155	NOT_PRODUCT(
duke@435	156	size_t returnedBytes() const { return _returnedBytes; }
duke@435	157	void set_returnedBytes(size_t v) { _returnedBytes = v; }
duke@435	158	)
duke@435	159	};