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Change bits of waitable atomics

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Reduce max waiter count to 2^14.
Refactor code to use waiter_mask and signal_mask constants.
This commit is contained in:
Nekotekina 2019-07-29 20:28:20 +03:00
parent e1db6cef6f
commit c6993d3f1c
1 changed files with 20 additions and 14 deletions
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34
rpcs3/util/atomic.cpp
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@ -8,6 +8,12 @@ static constexpr std::uintptr_t s_hashtable_size = 1u << 21;
// TODO: it's probably better to implement more effective futex emulation for OSX/BSD here. // TODO: it's probably better to implement more effective futex emulation for OSX/BSD here.
static atomic_t<s64> s_hashtable[s_hashtable_size]; static atomic_t<s64> s_hashtable[s_hashtable_size];
// Max number of waiters (16383)
static constexpr s64 s_waiter_mask = 0x3fff;
// Implementation detail (remaining bits out of 32)
static constexpr s64 s_signal_mask = 0xffffffff & ~s_waiter_mask;
static inline bool ptr_cmp(const void* data, std::size_t size, u64 old_value) static inline bool ptr_cmp(const void* data, std::size_t size, u64 old_value)
{ {
switch (size) switch (size)
@ -39,7 +45,7 @@ void atomic_storage_futex::wait(const void* data, std::size_t size, u64 old_valu
const auto [_, ok] = entry.fetch_op([&](s64& value) const auto [_, ok] = entry.fetch_op([&](s64& value)
{ {
if ((value & 0xffff) == 0xffff || (value & 0xffff0000) == s64{0xffff0000}) if ((value & s_waiter_mask) == s_waiter_mask || (value & s_signal_mask) == s_signal_mask)
{ {
// Return immediately on waiter overflow or signal overflow // Return immediately on waiter overflow or signal overflow
return false; return false;
@ -56,7 +62,7 @@ void atomic_storage_futex::wait(const void* data, std::size_t size, u64 old_valu
value &= 0xffffffff; value &= 0xffffffff;
} }
new_value = static_cast<u32>(++value); new_value = static_cast<u32>(value += 1);
return true; return true;
}); });
@ -80,11 +86,11 @@ void atomic_storage_futex::wait(const void* data, std::size_t size, u64 old_valu
// Try to decrement // Try to decrement
const auto [prev, ok] = entry.fetch_op([&](s64& value) const auto [prev, ok] = entry.fetch_op([&](s64& value)
{ {
if (value & 0xffff) if (value & s_waiter_mask)
{ {
value--; value -= 1;
if ((value & 0xffff) == 0) if ((value & s_waiter_mask) == 0)
{ {
// Reset on last waiter // Reset on last waiter
value = 0; value = 0;
@ -131,25 +137,25 @@ void atomic_storage_futex::notify_one(const void* data)
const auto [prev, ok] = entry.fetch_op([&](s64& value) const auto [prev, ok] = entry.fetch_op([&](s64& value)
{ {
if (value & 0xffff && (value >> 32) == (iptr >> 16)) if (value & s_waiter_mask && (value >> 32) == (iptr >> 16))
{ {
#ifdef _WIN32 #ifdef _WIN32
// Try to decrement if no collision // Try to decrement if no collision
value--; value -= 1;
if ((value & 0xffff) == 0) if ((value & s_waiter_mask) == 0)
{ {
// Reset on last waiter // Reset on last waiter
value = 0; value = 0;
} }
#else #else
if ((value & 0xffff0000) == s64{0xffff0000}) if ((value & s_signal_mask) == s_signal_mask)
{ {
// Signal overflow, do nothing // Signal overflow, do nothing
return false; return false;
} }
value += 0x10000; value += s_signal_mask & -s_signal_mask;
#endif #endif
return true; return true;
@ -192,22 +198,22 @@ void atomic_storage_futex::notify_all(const void* data)
// Consume everything // Consume everything
#ifdef _WIN32 #ifdef _WIN32
for (uint count = static_cast<u16>(entry.exchange(0)); count; count--) for (s64 count = entry.exchange(0) & s_waiter_mask; count; count--)
{ {
NtReleaseKeyedEvent(nullptr, &entry, false, nullptr); NtReleaseKeyedEvent(nullptr, &entry, false, nullptr);
} }
#else #else
const auto [_, ok] = entry.fetch_op([&](s64& value) const auto [_, ok] = entry.fetch_op([&](s64& value)
{ {
if (value & 0xffff) if (value & s_waiter_mask)
{ {
if ((value & 0xffff0000) == s64{0xffff0000}) if ((value & s_signal_mask) == s_signal_mask)
{ {
// Signal overflow, do nothing // Signal overflow, do nothing
return false; return false;
} }
value += 0x10000; value += s_signal_mask & -s_signal_mask;
return true; return true;
} }