28 #include "trace/tracing.hpp"
29
30 void G1EvacStats::adjust_desired_plab_sz() {
31 if (PrintPLAB) {
32 gclog_or_tty->print(" (allocated = " SIZE_FORMAT " wasted = " SIZE_FORMAT " "
33 "unused = " SIZE_FORMAT " used = " SIZE_FORMAT " "
34 "undo_waste = " SIZE_FORMAT " region_end_waste = " SIZE_FORMAT " "
35 "regions filled = %u direct_allocated = " SIZE_FORMAT " "
36 "failure_used = " SIZE_FORMAT " failure_waste = " SIZE_FORMAT ") ",
37 _allocated, _wasted, _unused, used(), _undo_wasted, _region_end_waste,
38 _regions_filled, _direct_allocated, _failure_used, _failure_waste);
39 }
40
41 if (ResizePLAB) {
42
43 assert(is_object_aligned(max_size()) && min_size() <= max_size(),
44 "PLAB clipping computation may be incorrect");
45
46 if (_allocated == 0) {
47 assert((_unused == 0),
48 err_msg("Inconsistency in PLAB stats: "
49 "_allocated: " SIZE_FORMAT ", "
50 "_wasted: " SIZE_FORMAT ", "
51 "_region_end_waste: " SIZE_FORMAT ", "
52 "_unused: " SIZE_FORMAT ", "
53 "_used : " SIZE_FORMAT,
54 _allocated, _wasted, _region_end_waste, _unused, used()));
55 _allocated = 1;
56 }
57 // The size of the PLAB caps the amount of space that can be wasted at the
58 // end of the collection. In the worst case the last PLAB could be completely
59 // empty.
60 // This allows us to calculate the new PLAB size to achieve the
61 // TargetPLABWastePct given the latest memory usage and that the last buffer
62 // will be G1LastPLABAverageOccupancy full.
63 //
64 // E.g. assume that if in the current GC 100 words were allocated and a
65 // TargetPLABWastePct of 10 had been set.
66 //
67 // So we could waste up to 10 words to meet that percentage. Given that we
68 // also assume that that buffer is typically half-full, the new desired PLAB
69 // size is set to 20 words.
70 //
71 // The amount of allocation performed should be independent of the number of
72 // threads, so should the maximum waste we can spend in total. So if
73 // we used n threads to allocate, each of them can spend maximum waste/n words in
74 // a first rough approximation. The number of threads only comes into play later
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28 #include "trace/tracing.hpp"
29
30 void G1EvacStats::adjust_desired_plab_sz() {
31 if (PrintPLAB) {
32 gclog_or_tty->print(" (allocated = " SIZE_FORMAT " wasted = " SIZE_FORMAT " "
33 "unused = " SIZE_FORMAT " used = " SIZE_FORMAT " "
34 "undo_waste = " SIZE_FORMAT " region_end_waste = " SIZE_FORMAT " "
35 "regions filled = %u direct_allocated = " SIZE_FORMAT " "
36 "failure_used = " SIZE_FORMAT " failure_waste = " SIZE_FORMAT ") ",
37 _allocated, _wasted, _unused, used(), _undo_wasted, _region_end_waste,
38 _regions_filled, _direct_allocated, _failure_used, _failure_waste);
39 }
40
41 if (ResizePLAB) {
42
43 assert(is_object_aligned(max_size()) && min_size() <= max_size(),
44 "PLAB clipping computation may be incorrect");
45
46 if (_allocated == 0) {
47 assert((_unused == 0),
48 "Inconsistency in PLAB stats: "
49 "_allocated: " SIZE_FORMAT ", "
50 "_wasted: " SIZE_FORMAT ", "
51 "_region_end_waste: " SIZE_FORMAT ", "
52 "_unused: " SIZE_FORMAT ", "
53 "_used : " SIZE_FORMAT,
54 _allocated, _wasted, _region_end_waste, _unused, used());
55 _allocated = 1;
56 }
57 // The size of the PLAB caps the amount of space that can be wasted at the
58 // end of the collection. In the worst case the last PLAB could be completely
59 // empty.
60 // This allows us to calculate the new PLAB size to achieve the
61 // TargetPLABWastePct given the latest memory usage and that the last buffer
62 // will be G1LastPLABAverageOccupancy full.
63 //
64 // E.g. assume that if in the current GC 100 words were allocated and a
65 // TargetPLABWastePct of 10 had been set.
66 //
67 // So we could waste up to 10 words to meet that percentage. Given that we
68 // also assume that that buffer is typically half-full, the new desired PLAB
69 // size is set to 20 words.
70 //
71 // The amount of allocation performed should be independent of the number of
72 // threads, so should the maximum waste we can spend in total. So if
73 // we used n threads to allocate, each of them can spend maximum waste/n words in
74 // a first rough approximation. The number of threads only comes into play later
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