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8148099: Improve memory access to FromCardCache during GC

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Transpose the FromCardCache data array so the access during GC is linear instead of element-by-element with stride.

Reviewed-by: mgerdin, brutisso
This commit is contained in:
Thomas Schatzl 2016-04-01 11:57:58 +02:00
parent 0c5e3bcbd6
commit f8070cc44a
2 changed files with 10 additions and 7 deletions
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6
hotspot/src/share/vm/gc/g1/g1FromCardCache.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -37,8 +37,8 @@ void G1FromCardCache::initialize(uint num_par_rem_sets, uint max_num_regions) {
guarantee(_cache == NULL, "Should not call this multiple times");
_max_regions = max_num_regions;
_cache = Padded2DArray<int, mtGC>::create_unfreeable(num_par_rem_sets,
_max_regions,
_cache = Padded2DArray<int, mtGC>::create_unfreeable(_max_regions,
num_par_rem_sets,
&_static_mem_size);
invalidate(0, _max_regions);

11
hotspot/src/share/vm/gc/g1/g1FromCardCache.hpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -32,8 +32,11 @@
// a per-region and per-thread basis.
class G1FromCardCache : public AllStatic {
private:
// Array of card indices. Indexed by thread X and heap region to minimize
// Array of card indices. Indexed by heap region (rows) and thread (columns) to minimize
// thread contention.
// This order minimizes the time to clear all entries for a given region during region
// freeing. I.e. a single clear of a single memory area instead of multiple separate
// accesses with a large stride per region.
static int** _cache;
static uint _max_regions;
static size_t _static_mem_size;
@ -58,11 +61,11 @@ class G1FromCardCache : public AllStatic {
}
static int at(uint worker_id, uint region_idx) {
return _cache[worker_id][region_idx];
return _cache[region_idx][worker_id];
}
static void set(uint worker_id, uint region_idx, int val) {
_cache[worker_id][region_idx] = val;
_cache[region_idx][worker_id] = val;
}
static void initialize(uint num_par_rem_sets, uint max_num_regions);