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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * published by the Free Software Foundation.

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  * 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.

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 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP

 #include "utilities/macros.hpp"

 #include "memory/allocation.hpp"

 #include "utilities/globalDefinitions.hpp"

 #include "gc_implementation/shared/gcUtil.hpp"

 class AllocationStats VALUE_OBJ_CLASS_SPEC {

   // A duration threshold (in ms) used to filter

   // possibly unreliable samples.

   static float _threshold;

   // We measure the demand between the end of the previous sweep and

   // beginning of this sweep:

   //   Count(end_last_sweep) - Count(start_this_sweep)

   //     + split_births(between) - split_deaths(between)

   // The above number divided by the time since the end of the

   // previous sweep gives us a time rate of demand for blocks

   // of this size. We compute a padded average of this rate as

   // our current estimate for the time rate of demand for blocks

   // of this size. Similarly, we keep a padded average for the time

   // between sweeps. Our current estimate for demand for blocks of

   // this size is then simply computed as the product of these two

   // estimates.

   AdaptivePaddedAverage _demand_rate_estimate;

   ssize_t     _desired;         // Demand stimate computed as described above

   ssize_t     _coal_desired;     // desired +/- small-percent for tuning coalescing

   ssize_t     _surplus;         // count - (desired +/- small-percent),

                                 // used to tune splitting in best fit

   ssize_t     _bfr_surp;         // surplus at start of current sweep

   ssize_t     _prev_sweep;       // count from end of previous sweep

   ssize_t     _before_sweep;     // count from before current sweep

   ssize_t     _coal_births;      // additional chunks from coalescing

   ssize_t     _coal_deaths;      // loss from coalescing

   ssize_t     _split_births;     // additional chunks from splitting

   ssize_t     _split_deaths;     // loss from splitting

   size_t      _returned_bytes;   // number of bytes returned to list.

  public:

   void initialize(bool split_birth = false) {

     AdaptivePaddedAverage* dummy =

       new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight,

                                                          CMS_FLSPadding);

     _desired = 0;

     _coal_desired = 0;

     _surplus = 0;

     _bfr_surp = 0;

     _prev_sweep = 0;

     _before_sweep = 0;

     _coal_births = 0;

     _coal_deaths = 0;

     _split_births = (split_birth ? 1 : 0);

     _split_deaths = 0;

     _returned_bytes = 0;

   }

   AllocationStats() {

     initialize();

   }

   // The rate estimate is in blocks per second.

   void compute_desired(size_t count,

                        float inter_sweep_current,

                        float inter_sweep_estimate,

                        float intra_sweep_estimate) {

     // If the latest inter-sweep time is below our granularity

     // of measurement, we may call in here with

     // inter_sweep_current == 0. However, even for suitably small

     // but non-zero inter-sweep durations, we may not trust the accuracy

     // of accumulated data, since it has not been "integrated"

     // (read "low-pass-filtered") long enough, and would be

     // vulnerable to noisy glitches. In such cases, we

     // ignore the current sample and use currently available

     // historical estimates.

     assert(prev_sweep() + split_births() + coal_births()        // "Total Production Stock"

            >= split_deaths() + coal_deaths() + (ssize_t)count, // "Current stock + depletion"

            "Conservation Principle");

     if (inter_sweep_current > _threshold) {

       ssize_t demand = prev_sweep() - (ssize_t)count + split_births() + coal_births()

                        - split_deaths() - coal_deaths();

       assert(demand >= 0,

              err_msg("Demand (" SSIZE_FORMAT ") should be non-negative for "

                      PTR_FORMAT " (size=" SIZE_FORMAT ")",

                      demand, this, count));

       // Defensive: adjust for imprecision in event counting

       if (demand < 0) {

         demand = 0;

       }

       float old_rate = _demand_rate_estimate.padded_average();

       float rate = ((float)demand)/inter_sweep_current;

       _demand_rate_estimate.sample(rate);

       float new_rate = _demand_rate_estimate.padded_average();

       ssize_t old_desired = _desired;

       float delta_ise = (CMSExtrapolateSweep ? intra_sweep_estimate : 0.0);

       _desired = (ssize_t)(new_rate * (inter_sweep_estimate + delta_ise));

       if (PrintFLSStatistics > 1) {

         gclog_or_tty->print_cr("demand: %d, old_rate: %f, current_rate: %f, new_rate: %f, old_desired: %d, new_desired: %d",

                                 demand,     old_rate,     rate,             new_rate,     old_desired,     _desired);

       }

     }

   }

   ssize_t desired() const { return _desired; }

   void set_desired(ssize_t v) { _desired = v; }

   ssize_t coal_desired() const { return _coal_desired; }

   void set_coal_desired(ssize_t v) { _coal_desired = v; }

   ssize_t surplus() const { return _surplus; }

   void set_surplus(ssize_t v) { _surplus = v; }

   void increment_surplus() { _surplus++; }

   void decrement_surplus() { _surplus--; }

   ssize_t bfr_surp() const { return _bfr_surp; }

   void set_bfr_surp(ssize_t v) { _bfr_surp = v; }

   ssize_t prev_sweep() const { return _prev_sweep; }

   void set_prev_sweep(ssize_t v) { _prev_sweep = v; }

   ssize_t before_sweep() const { return _before_sweep; }

   void set_before_sweep(ssize_t v) { _before_sweep = v; }

   ssize_t coal_births() const { return _coal_births; }

   void set_coal_births(ssize_t v) { _coal_births = v; }

   void increment_coal_births() { _coal_births++; }

   ssize_t coal_deaths() const { return _coal_deaths; }

   void set_coal_deaths(ssize_t v) { _coal_deaths = v; }

   void increment_coal_deaths() { _coal_deaths++; }

   ssize_t split_births() const { return _split_births; }

   void set_split_births(ssize_t v) { _split_births = v; }

   void increment_split_births() { _split_births++; }

   ssize_t split_deaths() const { return _split_deaths; }

   void set_split_deaths(ssize_t v) { _split_deaths = v; }

   void increment_split_deaths() { _split_deaths++; }

   NOT_PRODUCT(

     size_t returned_bytes() const { return _returned_bytes; }

     void set_returned_bytes(size_t v) { _returned_bytes = v; }

   )

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP