599       double threshold = -reset_val + (CodeCache::reverse_free_ratio(code_blob_type) * NmethodSweepActivity);
 600       // The less free space in the code cache we have - the bigger reverse_free_ratio() is.
 601       // I.e., 'threshold' increases with lower available space in the code cache and a higher
 602       // NmethodSweepActivity. If the current hotness counter - which decreases from its initial
 603       // value until it is reset by stack walking - is smaller than the computed threshold, the
 604       // corresponding nmethod is considered for removal.
 605       if ((NmethodSweepActivity > 0) && (nm->hotness_counter() < threshold) && (time_since_reset > MinPassesBeforeFlush)) {
 606         // A method is marked as not-entrant if the method is
 607         // 1) 'old enough': nm->hotness_counter() < threshold
 608         // 2) The method was in_use for a minimum amount of time: (time_since_reset > MinPassesBeforeFlush)
 609         //    The second condition is necessary if we are dealing with very small code cache
 610         //    sizes (e.g., <10m) and the code cache size is too small to hold all hot methods.
 611         //    The second condition ensures that methods are not immediately made not-entrant
 612         //    after compilation.
 613         make_not_entrant = true;
 614       }
 615 
 616       // The stack-scanning low-cost detection may not see the method was used (which can happen for
 617       // flat profiles). Check the age counter for possible data.
 618       if (UseCodeAging && make_not_entrant && (nm->is_compiled_by_c2() || nm->is_compiled_by_c1())) {
 619         MethodCounters* mc = nm->method()->method_counters();
 620         if (mc == NULL) {
 621           // Sometimes we can get here without MethodCounters. For example if we run with -Xcomp.
 622           // Try to allocate them.
 623           mc = nm->method()->get_method_counters(Thread::current());
 624         }
 625         if (mc != NULL) {
 626           // Snapshot the value as it's changed concurrently
 627           int age = mc->nmethod_age();
 628           if (MethodCounters::is_nmethod_hot(age)) {
 629             // The method has gone through flushing, and it became relatively hot that it deopted
 630             // before we could take a look at it. Give it more time to appear in the stack traces,
 631             // proportional to the number of deopts.
 632             MethodData* md = nm->method()->method_data();
 633             if (md != NULL && time_since_reset > (int)(MinPassesBeforeFlush * (md->tenure_traps() + 1))) {
 634               // It's been long enough, we still haven't seen it on stack.
 635               // Try to flush it, but enable counters the next time.
 636               mc->reset_nmethod_age();
 637             } else {
 638               make_not_entrant = false;
 639             }
 640           } else if (MethodCounters::is_nmethod_warm(age)) {
 641             // Method has counters enabled, and the method was used within
 642             // previous MinPassesBeforeFlush sweeps. Reset the counter. Stay in the existing
 643             // compiled state.
 644             mc->reset_nmethod_age();

 599       double threshold = -reset_val + (CodeCache::reverse_free_ratio(code_blob_type) * NmethodSweepActivity);
 600       // The less free space in the code cache we have - the bigger reverse_free_ratio() is.
 601       // I.e., 'threshold' increases with lower available space in the code cache and a higher
 602       // NmethodSweepActivity. If the current hotness counter - which decreases from its initial
 603       // value until it is reset by stack walking - is smaller than the computed threshold, the
 604       // corresponding nmethod is considered for removal.
 605       if ((NmethodSweepActivity > 0) && (nm->hotness_counter() < threshold) && (time_since_reset > MinPassesBeforeFlush)) {
 606         // A method is marked as not-entrant if the method is
 607         // 1) 'old enough': nm->hotness_counter() < threshold
 608         // 2) The method was in_use for a minimum amount of time: (time_since_reset > MinPassesBeforeFlush)
 609         //    The second condition is necessary if we are dealing with very small code cache
 610         //    sizes (e.g., <10m) and the code cache size is too small to hold all hot methods.
 611         //    The second condition ensures that methods are not immediately made not-entrant
 612         //    after compilation.
 613         make_not_entrant = true;
 614       }
 615 
 616       // The stack-scanning low-cost detection may not see the method was used (which can happen for
 617       // flat profiles). Check the age counter for possible data.
 618       if (UseCodeAging && make_not_entrant && (nm->is_compiled_by_c2() || nm->is_compiled_by_c1())) {
 619         MethodCounters* mc = nm->method()->get_method_counters(Thread::current());





 620         if (mc != NULL) {
 621           // Snapshot the value as it's changed concurrently
 622           int age = mc->nmethod_age();
 623           if (MethodCounters::is_nmethod_hot(age)) {
 624             // The method has gone through flushing, and it became relatively hot that it deopted
 625             // before we could take a look at it. Give it more time to appear in the stack traces,
 626             // proportional to the number of deopts.
 627             MethodData* md = nm->method()->method_data();
 628             if (md != NULL && time_since_reset > (int)(MinPassesBeforeFlush * (md->tenure_traps() + 1))) {
 629               // It's been long enough, we still haven't seen it on stack.
 630               // Try to flush it, but enable counters the next time.
 631               mc->reset_nmethod_age();
 632             } else {
 633               make_not_entrant = false;
 634             }
 635           } else if (MethodCounters::is_nmethod_warm(age)) {
 636             // Method has counters enabled, and the method was used within
 637             // previous MinPassesBeforeFlush sweeps. Reset the counter. Stay in the existing
 638             // compiled state.
 639             mc->reset_nmethod_age();