mirror of
https://github.com/RPCS3/rpcs3.git
synced 2024-11-23 03:02:53 +01:00
atomic.cpp: various cleanups and fixes
Add pointer comparison to notifiers (to prevent spurious wakeups). Fix a bug with a possible double notification in raw_notify(). Fix a bug with incorrect allocatin bit slots for cond_handle. Add a semaphore counter to track max allowed number of threads. Use #define for some constants to STRINGIZE them in errors. Add some error messages when certain limits are reached. Fix a bug with a wrong check simply throwing std::abort. Use "special" notify_all patch with batch processing for every arch. Fix Win7 bug who no one probably noticed.
This commit is contained in:
Nekotekina
parent
cc07e5306e
commit
1bb7c74c93
@ -80,6 +80,8 @@ ptr_cmp(const void* data, u32 size, __m128i old128, __m128i mask128)
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{
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return true;
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}
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break;
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}
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default:
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{
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@ -138,7 +140,7 @@ cmp_mask(u32 size1, __m128i mask1, __m128i val1, u32 size2, __m128i mask2, __m12
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namespace
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{
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// Essentially a fat semaphore
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struct cond_handle
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struct alignas(64) cond_handle
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{
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#ifdef _WIN32
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u64 tid = GetCurrentThreadId();
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@ -147,6 +149,8 @@ namespace
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#endif
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atomic_t<u32> sync{};
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u32 size{};
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u64 tsc0{};
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const void* ptr{};
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__m128i mask{};
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__m128i oldv{};
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@ -155,22 +159,46 @@ namespace
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std::condition_variable cond;
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std::mutex mtx;
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#endif
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bool forced_wakeup()
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{
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const auto [_old, ok] = sync.fetch_op([](u32& val)
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{
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if (val == 1 || val == 2)
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{
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val = 3;
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return true;
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}
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return false;
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});
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// Prevent collision between normal wake-up and forced one
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return ok && _old == 1;
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}
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};
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#ifndef USE_STD
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static_assert(sizeof(cond_handle) == 64);
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#endif
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}
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// Arbitrary max allowed thread number (to fit in 15 bits)
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static constexpr u32 s_max_conds = 512 * 64 - 1;
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// Max allowed thread number is chosen to fit in 15 bits
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static std::aligned_storage_t<sizeof(cond_handle), alignof(cond_handle)> s_cond_list[INT16_MAX]{};
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static std::aligned_storage_t<sizeof(cond_handle), alignof(cond_handle)> s_cond_list[s_max_conds]{};
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// Used to allow concurrent notifying
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static atomic_t<u16> s_cond_refs[INT16_MAX]{};
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atomic_t<u64, 64> s_cond_bits[s_max_conds / 64];
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// Allocation bits
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static atomic_t<u64, 64> s_cond_bits[::align<u32>(INT16_MAX, 64) / 64]{};
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atomic_t<u32, 64> s_cond_sema{0};
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// Allocation semaphore
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static atomic_t<u32, 64> s_cond_sema{0};
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static u32 cond_alloc()
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{
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// Determine whether there is a free slot or not
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if (!s_cond_sema.try_inc(s_max_conds + 1))
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if (!s_cond_sema.try_inc(INT16_MAX + 1))
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{
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return 0;
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}
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@ -184,9 +212,9 @@ static u32 cond_alloc()
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const u32 start = __rdtsc();
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#endif
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for (u32 i = start * 8;; i++)
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for (u32 i = start;; i++)
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{
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const u32 group = i % (s_max_conds / 64);
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const u32 group = i % ::size32(s_cond_bits);
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const auto [bits, ok] = s_cond_bits[group].fetch_op([](u64& bits)
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{
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@ -212,14 +240,14 @@ static u32 cond_alloc()
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}
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}
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// TODO: unreachable
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// Unreachable
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std::abort();
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return 0;
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}
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static cond_handle* cond_get(u32 cond_id)
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{
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if (cond_id - 1 < s_max_conds) [[likely]]
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if (cond_id - 1 < u32{INT16_MAX}) [[likely]]
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{
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return std::launder(reinterpret_cast<cond_handle*>(s_cond_list + (cond_id - 1)));
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}
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@ -229,7 +257,7 @@ static cond_handle* cond_get(u32 cond_id)
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static void cond_free(u32 cond_id)
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{
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if (cond_id - 1 >= s_max_conds)
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if (cond_id - 1 >= u32{INT16_MAX})
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{
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fprintf(stderr, "cond_free(): bad id %u" HERE "\n", cond_id);
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std::abort();
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@ -247,6 +275,8 @@ static void cond_free(u32 cond_id)
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namespace
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{
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#define MAX_THREADS (56)
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struct alignas(128) sync_var
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{
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constexpr sync_var() noexcept = default;
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@ -254,17 +284,17 @@ namespace
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// Reference counter, owning pointer, collision bit and optionally selected slot
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atomic_t<u64> addr_ref{};
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// Allocated semaphore bits (max 56, to make total size 128)
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atomic_t<u64> sema_bits{};
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// Semaphores (allocated in reverse order), 0 means empty, 0x8000 is notifier lock
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atomic_t<u16> sema_data[MAX_THREADS]{};
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// Semaphores (one per thread), data is platform-specific but 0 means empty
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atomic_t<u16> sema_data[56]{};
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// Allocated semaphore bits (to make total size 128)
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atomic_t<u64> sema_bits{};
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atomic_t<u16>* sema_alloc()
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{
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const auto [bits, ok] = sema_bits.fetch_op([](u64& bits)
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{
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if (bits + 1 < (1ull << 56))
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if (bits + 1 < (1ull << MAX_THREADS))
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{
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// Set lowest clear bit
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bits |= bits + 1;
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@ -280,6 +310,8 @@ namespace
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return &sema_data[std::countr_one(bits)];
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}
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// TODO: support extension if reached
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fmt::raw_error("Thread limit " STRINGIZE(MAX_THREADS) " for a single address reached in atomic wait.");
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return nullptr;
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}
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@ -287,6 +319,7 @@ namespace
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{
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if (sema < sema_data || sema >= std::end(sema_data))
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{
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fprintf(stderr, "sema_free(): bad sema ptr %p" HERE "\n", sema);
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std::abort();
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}
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@ -307,6 +340,8 @@ namespace
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};
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static_assert(sizeof(sync_var) == 128);
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#undef MAX_THREADS
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}
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// Main hashtable for atomic wait.
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@ -324,16 +359,28 @@ namespace
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}
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// Number of search groups (defines max slot branch count as gcount * 64)
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static constexpr u32 s_slot_gcount = (s_hashtable_power > 7 ? 4096 : 256) / 64;
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#define MAX_SLOTS (4096)
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// Array of slot branch objects
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alignas(128) static slot_info s_slot_list[s_slot_gcount * 64]{};
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alignas(128) static slot_info s_slot_list[MAX_SLOTS]{};
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// Allocation bits
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static atomic_t<u64, 64> s_slot_bits[s_slot_gcount]{};
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static atomic_t<u64, 64> s_slot_bits[MAX_SLOTS / 64]{};
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// Allocation semaphore
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static atomic_t<u32, 64> s_slot_sema{0};
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static_assert(MAX_SLOTS % 64 == 0);
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static u64 slot_alloc()
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{
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// Determine whether there is a free slot or not
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if (!s_slot_sema.try_inc(MAX_SLOTS + 1))
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{
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fmt::raw_error("Hashtable extension slot limit " STRINGIZE(MAX_SLOTS) " reached in atomic wait.");
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return 0;
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}
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// Diversify search start points to reduce contention and increase immediate success chance
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#ifdef _WIN32
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const u32 start = GetCurrentProcessorNumber();
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@ -343,9 +390,9 @@ static u64 slot_alloc()
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const u32 start = __rdtsc();
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#endif
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for (u32 i = 0;; i++)
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for (u32 i = start;; i++)
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{
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const u32 group = (i + start * 8) % s_slot_gcount;
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const u32 group = i % ::size32(s_slot_bits);
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const auto [bits, ok] = s_slot_bits[group].fetch_op([](u64& bits)
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{
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@ -366,11 +413,13 @@ static u64 slot_alloc()
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}
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}
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// TODO: unreachable
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// Unreachable
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std::abort();
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return 0;
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}
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#undef MAX_SLOTS
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static sync_var* slot_get(std::uintptr_t iptr, sync_var* loc, u64 lv = 0)
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{
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if (!loc)
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@ -407,6 +456,9 @@ static void slot_free(u64 id)
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// Reset allocation bit
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id = (id & s_slot_mask) / one_v<s_slot_mask>;
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s_slot_bits[id / 64] &= ~(1ull << (id % 64));
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// Reset semaphore
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s_slot_sema--;
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}
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static void slot_free(std::uintptr_t iptr, sync_var* loc, u64 lv = 0)
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@ -415,10 +467,8 @@ static void slot_free(std::uintptr_t iptr, sync_var* loc, u64 lv = 0)
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if ((value & s_pointer_mask) != (iptr & s_pointer_mask))
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{
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if ((value & s_waiter_mask) == 0 || (value & s_collision_bit) == 0)
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{
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std::abort();
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}
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ASSERT(value & s_waiter_mask);
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ASSERT(value & s_collision_bit);
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// Get the number of leading equal bits to determine subslot
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const u64 eq_bits = std::countl_zero<u64>((((iptr ^ value) & (s_pointer_mask >> lv)) | ~s_pointer_mask) << 16);
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@ -430,7 +480,7 @@ static void slot_free(std::uintptr_t iptr, sync_var* loc, u64 lv = 0)
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// Actual cleanup in reverse order
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auto [_old, ok] = loc->addr_ref.fetch_op([&](u64& value)
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{
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if (value & s_waiter_mask)
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ASSERT(value & s_waiter_mask);
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{
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value -= one_v<s_waiter_mask>;
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@ -443,15 +493,10 @@ static void slot_free(std::uintptr_t iptr, sync_var* loc, u64 lv = 0)
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return 1;
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}
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std::abort();
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});
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if (ok > 1 && _old & s_collision_bit)
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{
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if (loc->sema_bits)
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std::abort();
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// Deallocate slot on last waiter
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slot_free(_old);
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}
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@ -562,7 +607,7 @@ atomic_storage_futex::wait(const void* data, u32 size, __m128i old_value, u64 ti
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if (cond_id == 0)
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{
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fmt::raw_error("Thread limit (32767) reached in atomic wait.");
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fmt::raw_error("Thread limit " STRINGIZE(INT16_MAX) " reached in atomic wait.");
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}
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auto sema = slot->sema_alloc();
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@ -584,13 +629,15 @@ atomic_storage_futex::wait(const void* data, u32 size, __m128i old_value, u64 ti
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// Save for notifiers
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const auto cond = cond_get(cond_id);
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// Store some info for notifiers
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// Store some info for notifiers (some may be unused)
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cond->size = size;
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cond->mask = mask;
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cond->oldv = old_value;
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cond->ptr = data;
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cond->tsc0 = __rdtsc();
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cond->sync = 1;
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sema->release(cond_id);
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sema->store(static_cast<u16>(cond_id));
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#ifdef USE_STD
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// Lock mutex
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@ -604,7 +651,7 @@ atomic_storage_futex::wait(const void* data, u32 size, __m128i old_value, u64 ti
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bool fallback = false;
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#endif
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while (ptr_cmp(data, size, old_value, mask) && cond->sync != 3)
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while (ptr_cmp(data, size, old_value, mask))
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{
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#ifdef USE_FUTEX
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struct timespec ts;
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@ -652,7 +699,7 @@ atomic_storage_futex::wait(const void* data, u32 size, __m128i old_value, u64 ti
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if (fallback) [[unlikely]]
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{
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if (!cond->sync.compare_and_swap_test(2, 1))
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if (cond->sync.load() == 3 || !cond->sync.compare_and_swap_test(2, 1))
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{
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fallback = false;
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break;
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@ -751,15 +798,6 @@ alert_sema(atomic_t<u16>* sema, const void* data, u64 info, u32 size, __m128i ma
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return false;
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}
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// Dirty optimization: prevent attempting to lock dead or uninitialized sync vars
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u32 sync_var = 0;
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std::memcpy(&sync_var, reinterpret_cast<char*>(s_cond_list) + (sizeof(cond_handle) * (id - 1) + offsetof(cond_handle, sync)), sizeof(sync_var));
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if (!sync_var)
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{
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return false;
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}
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// Set notify lock
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id |= 0x8000;
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return true;
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@ -774,43 +812,30 @@ alert_sema(atomic_t<u16>* sema, const void* data, u64 info, u32 size, __m128i ma
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ok = false;
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if (cond && cond->sync && (!size ? (!info || cond->tid == info) : cmp_mask(size, mask, new_value, cond->size, cond->mask, cond->oldv)))
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if (cond && cond->sync && (!size ? (!info || cond->tid == info) : cond->ptr == data && cmp_mask(size, mask, new_value, cond->size, cond->mask, cond->oldv)))
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{
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if ((!size && cond->sync.exchange(3) == 1) || (size && cond->sync.load() == 1 && cond->sync.compare_and_swap_test(1, 2)))
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if ((!size && cond->forced_wakeup()) || (size && cond->sync.load() == 1 && cond->sync.compare_and_swap_test(1, 2)))
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{
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// Imminent notification
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if (!size || !info)
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{
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s_tls_notify_cb(data, 0);
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}
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ok = true;
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#ifdef USE_FUTEX
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// Use "wake all" arg for robustness, only 1 thread is expected
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futex(&cond->sync, FUTEX_WAKE_PRIVATE, 0x7fff'ffff);
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ok = true;
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#elif defined(USE_STD)
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// Not super efficient: locking is required to avoid lost notifications
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cond->mtx.lock();
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cond->mtx.unlock();
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cond->cond.notify_all();
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ok = true;
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#elif defined(_WIN32)
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if (NtWaitForAlertByThreadId)
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{
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if (NtAlertThreadByThreadId(cond->tid) == NTSTATUS_SUCCESS)
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{
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// Could be some dead thread otherwise
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ok = true;
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}
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// Sets some sticky alert bit, at least I believe so
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NtAlertThreadByThreadId(cond->tid);
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}
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else
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{
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// Can wait in rare cases, which is its annoying weakness
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if (NtReleaseKeyedEvent(nullptr, sema, 1, nullptr) == NTSTATUS_SUCCESS)
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{
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// Can't fail
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ok = true;
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}
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NtReleaseKeyedEvent(nullptr, sema, 1, nullptr);
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}
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#endif
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}
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@ -866,6 +891,8 @@ bool atomic_storage_futex::raw_notify(const void* data, u64 thread_id)
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return false;
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}
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s_tls_notify_cb(data, 0);
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u64 progress = 0;
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for (u64 bits = slot->sema_bits.load(); bits; bits &= bits - 1)
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@ -906,6 +933,8 @@ atomic_storage_futex::notify_one(const void* data, u32 size, __m128i mask, __m12
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return;
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}
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s_tls_notify_cb(data, 0);
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u64 progress = 0;
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for (u64 bits = slot->sema_bits; bits; bits &= bits - 1)
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@ -922,7 +951,7 @@ atomic_storage_futex::notify_one(const void* data, u32 size, __m128i mask, __m12
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s_tls_notify_cb(data, -1);
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}
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void
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SAFE_BUFFERS void
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#ifdef _WIN32
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__vectorcall
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#endif
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@ -937,18 +966,19 @@ atomic_storage_futex::notify_all(const void* data, u32 size, __m128i mask, __m12
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return;
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}
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s_tls_notify_cb(data, 0);
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u64 progress = 0;
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#if defined(_WIN32) && !defined(USE_FUTEX) && !defined(USE_STD)
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#if defined(_WIN32) && !defined(USE_FUTEX)
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// Special path for Windows 7
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if (!NtAlertThreadByThreadId)
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#elif defined(USE_STD)
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{
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// Make a copy to filter out waiters that fail some checks
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u64 copy = slot->sema_bits.load();
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u64 lock = 0;
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u32 lock_ids[56]{};
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static LARGE_INTEGER instant{};
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u32 lock_ids[64]{};
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for (u64 bits = copy; bits; bits &= bits - 1)
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{
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@ -963,15 +993,6 @@ atomic_storage_futex::notify_all(const void* data, u32 size, __m128i mask, __m12
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return false;
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}
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u32 sync_var = 0;
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std::memcpy(&sync_var, reinterpret_cast<char*>(s_cond_list) + (sizeof(cond_handle) * (id - 1) + offsetof(cond_handle, sync)), sizeof(sync_var));
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|
||||
if (!sync_var)
|
||||
{
|
||||
return false;
|
||||
}
|
||||
|
||||
// Set notify lock
|
||||
id |= 0x8000;
|
||||
return true;
|
||||
});
|
||||
@ -984,15 +1005,10 @@ atomic_storage_futex::notify_all(const void* data, u32 size, __m128i mask, __m12
|
||||
|
||||
const auto cond = cond_get(cond_id);
|
||||
|
||||
if (cond && cond->sync && cmp_mask(size, mask, new_value, cond->size, cond->mask, cond->oldv))
|
||||
if (cond && cond->sync && cond->ptr == data && cmp_mask(size, mask, new_value, cond->size, cond->mask, cond->oldv))
|
||||
{
|
||||
if (cond->sync.load() == 1 && cond->sync.compare_and_swap_test(1, 2))
|
||||
{
|
||||
if (bits == copy)
|
||||
{
|
||||
s_tls_notify_cb(data, 0);
|
||||
}
|
||||
|
||||
continue;
|
||||
}
|
||||
}
|
||||
@ -1011,11 +1027,26 @@ atomic_storage_futex::notify_all(const void* data, u32 size, __m128i mask, __m12
|
||||
|
||||
const auto sema = &slot->sema_data[id];
|
||||
|
||||
#ifdef USE_STD
|
||||
const auto cond = cond_get(lock_ids[id]);
|
||||
|
||||
// Optimistic non-blocking path
|
||||
if (cond->mtx.try_lock())
|
||||
{
|
||||
cond->mtx.unlock();
|
||||
cond->cond.notify_all();
|
||||
}
|
||||
else
|
||||
{
|
||||
continue;
|
||||
}
|
||||
#elif defined(_WIN32)
|
||||
if (NtReleaseKeyedEvent(nullptr, sema, 1, &instant) != NTSTATUS_SUCCESS)
|
||||
{
|
||||
// Failed to notify immediately
|
||||
continue;
|
||||
}
|
||||
#endif
|
||||
|
||||
s_tls_notify_cb(data, ++progress);
|
||||
|
||||
@ -1027,7 +1058,14 @@ atomic_storage_futex::notify_all(const void* data, u32 size, __m128i mask, __m12
|
||||
// Proceed with remaining bits using "normal" blocking waiting
|
||||
for (u64 bits = copy; bits; bits &= bits - 1)
|
||||
{
|
||||
NtReleaseKeyedEvent(nullptr, &slot->sema_data[std::countr_zero(bits)], 1, nullptr);
|
||||
#ifdef USE_STD
|
||||
const auto cond = cond_get(lock_ids[std::countr_zero(bits)]);
|
||||
cond->mtx.lock();
|
||||
cond->mtx.unlock();
|
||||
cond->cond.notify_all();
|
||||
#elif defined(_WIN32)
|
||||
NtReleaseKeyedEvent(nullptr, sema, 1, nullptr);
|
||||
#endif
|
||||
s_tls_notify_cb(data, ++progress);
|
||||
}
|
||||
|
||||
@ -1040,8 +1078,6 @@ atomic_storage_futex::notify_all(const void* data, u32 size, __m128i mask, __m12
|
||||
|
||||
if (sema->fetch_and(0x7fff) == 0x8000)
|
||||
{
|
||||
const u32 id = std::countr_zero(bits);
|
||||
|
||||
cond_free(lock_ids[id]);
|
||||
|
||||
slot->sema_bits &= ~(1ull << id);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user