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 void factor_vm::record_callstack_sample(cell* begin, cell* end, bool prolog_p) {
  43   *begin = sample_callstacks.size();
  44
  45   bool skip_p = prolog_p;
  46   auto recorder = [&](cell frame_top, cell size, code_block* owner, cell addr) {
  47     if (skip_p)
  48       skip_p = false;
  49     else
  50       sample_callstacks.push_back(owner->owner);
  51   };
  52   iterate_callstack(ctx, recorder);
  53
  54   *end = sample_callstacks.size();
  55
  56   std::reverse(sample_callstacks.begin() + *begin, sample_callstacks.end());
  57 }
  58
  59 void factor_vm::set_sampling_profiler(fixnum rate) {
  60   bool sampling_p = !!rate;
  61   if (sampling_p == !!atomic::load(&sampling_profiler_p))
  62     return;
  63
  64   if (sampling_p)
  65     start_sampling_profiler(rate);
  66   else
  67     end_sampling_profiler();
  68 }
  69
  70 void factor_vm::clear_samples() {
  71   // Swapping into temporaries releases the vector's allocated storage,
  72   // whereas clear() would leave the allocation as-is
  73   std::vector<profiling_sample> sample_graveyard;
  74   std::vector<cell> sample_callstack_graveyard;
  75   samples.swap(sample_graveyard);
  76   sample_callstacks.swap(sample_callstack_graveyard);
  77 }
  78
  79 void factor_vm::start_sampling_profiler(fixnum rate) {
  80   samples_per_second = rate;
  81   safepoint.sample_counts.clear();
  82   clear_samples();
  83   samples.reserve(10 * rate);
  84   sample_callstacks.reserve(100 * rate);
  85   atomic::store(&sampling_profiler_p, true);
  86   start_sampling_profiler_timer();
  87 }
  88
  89 void factor_vm::end_sampling_profiler() {
  90   atomic::store(&sampling_profiler_p, false);
  91   end_sampling_profiler_timer();
  92   record_sample(false);
  93 }
  94
  95 void factor_vm::primitive_sampling_profiler() {
  96   set_sampling_profiler(to_fixnum(ctx->pop()));
  97 }
  98
  99 /* Allocates memory */
 100 void factor_vm::primitive_get_samples() {
 101   if (atomic::load(&sampling_profiler_p) || samples.empty()) {
 102     ctx->push(false_object);
 103   } else {
 104     data_root<array> samples_array(allot_array(samples.size(), false_object),
 105                                    this);
 106     std::vector<profiling_sample>::const_iterator from_iter = samples.begin();
 107     cell to_i = 0;
 108
 109     for (; from_iter != samples.end(); ++from_iter, ++to_i) {
 110       data_root<array> sample(allot_array(7, false_object), this);
 111
 112       set_array_nth(sample.untagged(), 0,
 113                     tag_fixnum(from_iter->counts.sample_count));
 114       set_array_nth(sample.untagged(), 1,
 115                     tag_fixnum(from_iter->counts.gc_sample_count));
 116       set_array_nth(sample.untagged(), 2,
 117                     tag_fixnum(from_iter->counts.jit_sample_count));
 118       set_array_nth(sample.untagged(), 3,
 119                     tag_fixnum(from_iter->counts.foreign_sample_count));
 120       set_array_nth(sample.untagged(), 4,
 121                     tag_fixnum(from_iter->counts.foreign_thread_sample_count));
 122
 123       set_array_nth(sample.untagged(), 5, from_iter->thread);
 124
 125       cell callstack_size =
 126           from_iter->callstack_end - from_iter->callstack_begin;
 127       data_root<array> callstack(allot_array(callstack_size, false_object),
 128                                  this);
 129
 130       std::vector<cell>::const_iterator callstacks_begin =
 131                                             sample_callstacks.begin(),
 132                                         c_from_iter =
 133                                             callstacks_begin +
 134                                             from_iter->callstack_begin,
 135                                         c_from_iter_end =
 136                                             callstacks_begin +
 137                                             from_iter->callstack_end;
 138       cell c_to_i = 0;
 139
 140       for (; c_from_iter != c_from_iter_end; ++c_from_iter, ++c_to_i)
 141         set_array_nth(callstack.untagged(), c_to_i, *c_from_iter);
 142
 143       set_array_nth(sample.untagged(), 6, callstack.value());
 144
 145       set_array_nth(samples_array.untagged(), to_i, sample.value());
 146     }
 147     ctx->push(samples_array.value());
 148   }
 149 }
 150
 151 }