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Align StatisticsImpl / StatisticsData (#4036)

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Summary:
Pinned the alignment of StatisticsData to the cacheline size rather than just extending its size (which could go over two cache lines)if unaligned in allocation.

Avoid compile errors in the process as per individual commit messages.

strengthen static_assert to CACHELINE rather than the highest common multiple.
Closes https://github.com/facebook/rocksdb/pull/4036

Differential Revision: D8582844

Pulled By: yiwu-arbug

fbshipit-source-id: 363c37029f28e6093e06c60b987bca9aa204bc71
This commit is contained in:
Daniel Black 2018-06-25 22:42:35 -07:00 committed by Facebook Github Bot
parent 6d454d7376
commit 346d1069c3
2 changed files with 18 additions and 3 deletions
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4
Makefile
View File

@ -102,6 +102,10 @@ OPT += -momit-leaf-frame-pointer
endif
endif
ifeq (,$(shell $(CXX) -fsyntax-only -faligned-new -xc++ /dev/null 2>&1))
CXXFLAGS += -faligned-new -DHAVE_ALIGNED_NEW
endif
ifeq (,$(shell $(CXX) -fsyntax-only -maltivec -xc /dev/null 2>&1))
CXXFLAGS += -DHAS_ALTIVEC
CFLAGS += -DHAS_ALTIVEC

17
monitoring/statistics.h
View File

@ -22,6 +22,11 @@
#define ROCKSDB_FIELD_UNUSED
#endif // __clang__
#ifndef STRINGIFY
#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)
#endif
namespace rocksdb {
enum TickersInternal : uint32_t {
@ -35,7 +40,7 @@ enum HistogramsInternal : uint32_t {
};
class StatisticsImpl : public Statistics {
class ALIGN_AS(CACHE_LINE_SIZE) StatisticsImpl : public Statistics {
public:
StatisticsImpl(std::shared_ptr<Statistics> stats,
bool enable_internal_stats);
@ -69,17 +74,23 @@ class StatisticsImpl : public Statistics {
// cores can never share the same cache line.
//
// Alignment attributes expand to nothing depending on the platform
struct StatisticsData {
struct ALIGN_AS(CACHE_LINE_SIZE) StatisticsData {
std::atomic_uint_fast64_t tickers_[INTERNAL_TICKER_ENUM_MAX] = {{0}};
HistogramImpl histograms_[INTERNAL_HISTOGRAM_ENUM_MAX];
#ifndef HAVE_ALIGNED_NEW
char
padding[(CACHE_LINE_SIZE -
(INTERNAL_TICKER_ENUM_MAX * sizeof(std::atomic_uint_fast64_t) +
INTERNAL_HISTOGRAM_ENUM_MAX * sizeof(HistogramImpl)) %
CACHE_LINE_SIZE)] ROCKSDB_FIELD_UNUSED;
#endif
void *operator new(size_t s) { return port::cacheline_aligned_alloc(s); }
void *operator new[](size_t s) { return port::cacheline_aligned_alloc(s); }
void operator delete(void *p) { port::cacheline_aligned_free(p); }
void operator delete[](void *p) { port::cacheline_aligned_free(p); }
};
static_assert(sizeof(StatisticsData) % 64 == 0, "Expected 64-byte aligned");
static_assert(sizeof(StatisticsData) % CACHE_LINE_SIZE == 0, "Expected " TOSTRING(CACHE_LINE_SIZE) "-byte aligned");
CoreLocalArray<StatisticsData> per_core_stats_;