vm/sampling_profiler.cpp

   1 #include "master.hpp"
   2
   3 namespace factor {
   4
   5 profiling_sample_count profiling_sample_count::record_counts() volatile {
   6   atomic::fence();
   7   profiling_sample_count returned(sample_count, gc_sample_count,
   8                                   jit_sample_count, foreign_sample_count,
   9                                   foreign_thread_sample_count);
  10   atomic::fetch_subtract(&sample_count, returned.sample_count);
  11   atomic::fetch_subtract(&gc_sample_count, returned.gc_sample_count);
  12   atomic::fetch_subtract(&jit_sample_count, returned.jit_sample_count);
  13   atomic::fetch_subtract(&foreign_sample_count, returned.foreign_sample_count);
  14   atomic::fetch_subtract(&foreign_thread_sample_count,
  15                          returned.foreign_thread_sample_count);
  16   return returned;
  17 }
  18
  19 void profiling_sample_count::clear() volatile {
  20   sample_count = 0;
  21   gc_sample_count = 0;
  22   jit_sample_count = 0;
  23   foreign_sample_count = 0;
  24   foreign_thread_sample_count = 0;
  25   atomic::fence();
  26 }
  27
  28 profiling_sample::profiling_sample(factor_vm* vm, bool prolog_p,
  29                                    profiling_sample_count const& counts,
  30                                    cell thread)
  31     : counts(counts), thread(thread) {
  32   vm->record_callstack_sample(&callstack_begin, &callstack_end, prolog_p);
  33 }
  34
  35 void factor_vm::record_sample(bool prolog_p) {
  36   profiling_sample_count counts = safepoint.sample_counts.record_counts();
  37   if (!counts.empty())
  38     samples.push_back(profiling_sample(this, prolog_p, counts,
  39                                        special_objects[OBJ_CURRENT_THREAD]));
  40 }
  41
  42 struct record_callstack_sample_iterator {
  43   std::vector<cell>* sample_callstacks;
  44   bool skip_p;
  45
  46   record_callstack_sample_iterator(std::vector<cell>* sample_callstacks,
  47                                    bool prolog_p)
  48       : sample_callstacks(sample_callstacks), skip_p(prolog_p) {}
  49
  50   void operator()(cell frame_top, cell size, code_block* owner, cell addr) {
  51     if (skip_p)
  52       skip_p = false;
  53     else
  54       sample_callstacks->push_back(owner->owner);
  55   }
  56 };
  57
  58 void factor_vm::record_callstack_sample(cell* begin, cell* end, bool prolog_p) {
  59   *begin = sample_callstacks.size();
  60
  61   record_callstack_sample_iterator recorder(&sample_callstacks, prolog_p);
  62   iterate_callstack(ctx, recorder);
  63
  64   *end = sample_callstacks.size();
  65
  66   std::reverse(sample_callstacks.begin() + *begin, sample_callstacks.end());
  67 }
  68
  69 void factor_vm::set_sampling_profiler(fixnum rate) {
  70   bool sampling_p = !!rate;
  71   if (sampling_p == !!atomic::load(&sampling_profiler_p))
  72     return;
  73
  74   if (sampling_p)
  75     start_sampling_profiler(rate);
  76   else
  77     end_sampling_profiler();
  78 }
  79
  80 void factor_vm::clear_samples() {
  81   // Swapping into temporaries releases the vector's allocated storage,
  82   // whereas clear() would leave the allocation as-is
  83   std::vector<profiling_sample> sample_graveyard;
  84   std::vector<cell> sample_callstack_graveyard;
  85   samples.swap(sample_graveyard);
  86   sample_callstacks.swap(sample_callstack_graveyard);
  87 }
  88
  89 void factor_vm::start_sampling_profiler(fixnum rate) {
  90   samples_per_second = rate;
  91   safepoint.sample_counts.clear();
  92   clear_samples();
  93   samples.reserve(10 * rate);
  94   sample_callstacks.reserve(100 * rate);
  95   atomic::store(&sampling_profiler_p, true);
  96   start_sampling_profiler_timer();
  97 }
  98
  99 void factor_vm::end_sampling_profiler() {
 100   atomic::store(&sampling_profiler_p, false);
 101   end_sampling_profiler_timer();
 102   record_sample(false);
 103 }
 104
 105 void factor_vm::primitive_sampling_profiler() {
 106   set_sampling_profiler(to_fixnum(ctx->pop()));
 107 }
 108
 109 /* Allocates memory */
 110 void factor_vm::primitive_get_samples() {
 111   if (atomic::load(&sampling_profiler_p) || samples.empty()) {
 112     ctx->push(false_object);
 113   } else {
 114     data_root<array> samples_array(allot_array(samples.size(), false_object),
 115                                    this);
 116     std::vector<profiling_sample>::const_iterator from_iter = samples.begin();
 117     cell to_i = 0;
 118
 119     for (; from_iter != samples.end(); ++from_iter, ++to_i) {
 120       data_root<array> sample(allot_array(7, false_object), this);
 121
 122       set_array_nth(sample.untagged(), 0,
 123                     tag_fixnum(from_iter->counts.sample_count));
 124       set_array_nth(sample.untagged(), 1,
 125                     tag_fixnum(from_iter->counts.gc_sample_count));
 126       set_array_nth(sample.untagged(), 2,
 127                     tag_fixnum(from_iter->counts.jit_sample_count));
 128       set_array_nth(sample.untagged(), 3,
 129                     tag_fixnum(from_iter->counts.foreign_sample_count));
 130       set_array_nth(sample.untagged(), 4,
 131                     tag_fixnum(from_iter->counts.foreign_thread_sample_count));
 132
 133       set_array_nth(sample.untagged(), 5, from_iter->thread);
 134
 135       cell callstack_size =
 136           from_iter->callstack_end - from_iter->callstack_begin;
 137       data_root<array> callstack(allot_array(callstack_size, false_object),
 138                                  this);
 139
 140       std::vector<cell>::const_iterator callstacks_begin =
 141                                             sample_callstacks.begin(),
 142                                         c_from_iter =
 143                                             callstacks_begin +
 144                                             from_iter->callstack_begin,
 145                                         c_from_iter_end =
 146                                             callstacks_begin +
 147                                             from_iter->callstack_end;
 148       cell c_to_i = 0;
 149
 150       for (; c_from_iter != c_from_iter_end; ++c_from_iter, ++c_to_i)
 151         set_array_nth(callstack.untagged(), c_to_i, *c_from_iter);
 152
 153       set_array_nth(sample.untagged(), 6, callstack.value());
 154
 155       set_array_nth(samples_array.untagged(), to_i, sample.value());
 156     }
 157     ctx->push(samples_array.value());
 158   }
 159 }
 160
 161 void factor_vm::primitive_clear_samples() { clear_samples(); }
 162
 163 }