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8326586: Improve Speed of System.map

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Reviewed-by: jsjolen, gziemski
This commit is contained in:
Thomas Stuefe 2024-03-02 08:13:07 +00:00
parent a3d51d2027
commit 37e01efb78
1 changed files with 15 additions and 5 deletions
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20
src/hotspot/share/nmt/memMapPrinter.cpp
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@ -88,7 +88,7 @@ class CachedNMTInformation : public VirtualMemoryWalker {
// of them fit into a cache line.
Range* _ranges;
MEMFLAGS* _flags;
uintx _count, _capacity;
size_t _count, _capacity;
public:
CachedNMTInformation() : _ranges(nullptr), _flags(nullptr), _count(0), _capacity(0) {}
@ -107,12 +107,12 @@ public:
}
if (_count == _capacity) {
// Enlarge if needed
const uintx new_capacity = MAX2((uintx)4096, 2 * _capacity);
const size_t new_capacity = MAX2((size_t)4096, 2 * _capacity);
// Unfortunately, we need to allocate manually, raw, since we must prevent NMT deadlocks (ThreadCritical).
ALLOW_C_FUNCTION(realloc, _ranges = (Range*)::realloc(_ranges, new_capacity * sizeof(Range));)
ALLOW_C_FUNCTION(realloc, _flags = (MEMFLAGS*)::realloc(_flags, new_capacity * sizeof(MEMFLAGS));)
if (_ranges == nullptr || _flags == nullptr) {
// In case of OOM lets make no fuzz. Just return.
// In case of OOM lets make no fuss. Just return.
return false;
}
_capacity = new_capacity;
@ -127,11 +127,21 @@ public:
// Given a vma [from, to), find all regions that intersect with this vma and
// return their collective flags.
MemFlagBitmap lookup(const void* from, const void* to) const {
assert(from <= to, "Sanity");
// We optimize for sequential lookups. Since this class is used when a list
// of OS mappings is scanned (VirtualQuery, /proc/pid/maps), and these lists
// are usually sorted in order of addresses, ascending.
static uintx last = 0;
if (to <= _ranges[last].from) {
// the range is to the right of the given section, we need to re-start the search
last = 0;
}
MemFlagBitmap bm;
for(uintx i = 0; i < _count; i++) {
for(uintx i = last; i < _count; i++) {
if (range_intersects(from, to, _ranges[i].from, _ranges[i].to)) {
bm.set_flag(_flags[i]);
} else if (from < _ranges[i].to) {
} else if (to <= _ranges[i].from) {
last = i;
break;
}
}