stan/jdk-24
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

8283790: G1: Remove redundant card/heap-address transition

Browse Source 
Reviewed-by: tschatzl, iwalulya
This commit is contained in:
Albert Mingkun Yang 2022-04-19 11:56:06 +00:00
parent 647aa2aedd
commit b9f513c624
2 changed files with 36 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

86
src/hotspot/share/gc/g1/g1BlockOffsetTable.cpp
View File

@ -92,53 +92,39 @@ void G1BlockOffsetTablePart::update() {
assert(next_addr == limit, "Should stop the scan at the limit.");
}
// The arguments follow the normal convention of denoting
// a right-open interval: [start, end)
void G1BlockOffsetTablePart::set_remainder_to_point_to_start(HeapWord* start, HeapWord* end) {
assert(start < end, "precondition");
// Write the backskip value for each region.
//
// offset
// card 2nd 3rd
// | +- 1st | |
// v v v v
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
// |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ...
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
// 11 19 75
// 12
//
// offset card is the card that points to the start of an object
// x - offset value of offset card
// 1st - start of first logarithmic region
// 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1
// 2nd - start of second logarithmic region
// 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8
// 3rd - start of third logarithmic region
// 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64
//
// integer below the block offset entry is an example of
// the index of the entry
//
// Given an address,
// Find the index for the address
// Find the block offset table entry
// Convert the entry to a back slide
// (e.g., with today's, offset = 0x81 =>
// back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8
// Move back N (e.g., 8) entries and repeat with the
// value of the new entry
//
size_t start_card = _bot->index_for(start);
size_t end_card = _bot->index_for(end-1);
assert(start ==_bot->address_for_index(start_card), "Precondition");
assert(end ==_bot->address_for_index(end_card)+BOTConstants::card_size_in_words(), "Precondition");
set_remainder_to_point_to_start_incl(start_card, end_card); // closed interval
}
// Unlike the normal convention in this code, the argument here denotes
// a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start()
// above.
// Write the backskip value for each region.
//
// offset
// card 2nd 3rd
// | +- 1st | |
// v v v v
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
// |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ...
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
// 11 19 75
// 12
//
// offset card is the card that points to the start of an object
// x - offset value of offset card
// 1st - start of first logarithmic region
// 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1
// 2nd - start of second logarithmic region
// 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8
// 3rd - start of third logarithmic region
// 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64
//
// integer below the block offset entry is an example of
// the index of the entry
//
// Given an address,
// Find the index for the address
// Find the block offset table entry
// Convert the entry to a back slide
// (e.g., with today's, offset = 0x81 =>
// back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8
// Move back N (e.g., 8) entries and repeat with the
// value of the new entry
//
void G1BlockOffsetTablePart::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) {
assert(start_card <= end_card, "precondition");
assert(start_card > _bot->index_for(_hr->bottom()), "Cannot be first card");
@ -240,11 +226,7 @@ void G1BlockOffsetTablePart::update_for_block_work(HeapWord* blk_start,
// Are there more cards left to be updated?
if (index + 1 <= end_index) {
HeapWord* rem_st = _bot->address_for_index(index + 1);
// Calculate rem_end this way because end_index
// may be the last valid index in the covered region.
HeapWord* rem_end = _bot->address_for_index(end_index) + BOTConstants::card_size_in_words();
set_remainder_to_point_to_start(rem_st, rem_end);
set_remainder_to_point_to_start_incl(index + 1, end_index);
}
#ifdef ASSERT

9
src/hotspot/share/gc/g1/g1BlockOffsetTable.hpp
View File

@ -117,13 +117,8 @@ private:
// The region that owns this subregion.
HeapRegion* _hr;
// Sets the entries
// corresponding to the cards starting at "start" and ending at "end"
// to point back to the card before "start": the interval [start, end)
// is right-open.
void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end);
// Same as above, except that the args here are a card _index_ interval
// that is closed: [start_index, end_index]
// Sets the entries corresponding to the cards starting at "start" and ending
// at "end" to point back to the card before "start"; [start, end]
void set_remainder_to_point_to_start_incl(size_t start, size_t end);
inline size_t block_size(const HeapWord* p) const;