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atomic.cpp: optimize raw_notify() for unspecified pointer mode

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Remove unnecessary optimization from cond_alloc().
Optimistic case was absolutely dominating anyway.
Although the whole function is a dirty hack.
Now scanning through all threads is faster.
This commit is contained in:
Nekotekina 2020-11-13 05:32:50 +03:00
parent debfae06a8
commit cfda4d0ade
1 changed files with 43 additions and 13 deletions
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56
rpcs3/util/atomic.cpp
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@ -532,7 +532,10 @@ static atomic_wait::cond_handle s_cond_list[UINT16_MAX + 1]{};
static atomic_t<u64, 64> s_cond_bits[(UINT16_MAX + 1) / 64]{};
// Allocation semaphore
static atomic_t<u32, 64> s_cond_sema{0};
static atomic_t<u32> s_cond_sema{0};
// Max possible search distance (max i in loop)
static atomic_t<u32> s_cond_max{0};
static u32
#ifdef _WIN32
@ -548,16 +551,7 @@ cond_alloc(std::uintptr_t iptr, __m128i mask)
return 0;
}
// Diversify search start points to reduce contention and increase immediate success chance
#ifdef _WIN32
const u32 start = GetCurrentProcessorNumber();
#elif __linux__
const u32 start = sched_getcpu();
#else
const u32 start = __rdtsc();
#endif
for (u32 i = start;; i++)
for (u32 i = 0;; i++)
{
const u32 group = i % ::size32(s_cond_bits);
@ -588,6 +582,18 @@ cond_alloc(std::uintptr_t iptr, __m128i mask)
s_cond_list[id].mask = mask;
s_cond_list[id].init(iptr);
// Update some stats
s_cond_max.fetch_op([i](u32& val)
{
if (val < i)
{
val = i;
return true;
}
return false;
});
return id;
}
}
@ -1373,9 +1379,33 @@ bool atomic_wait_engine::raw_notify(const void* data, u64 thread_id)
// Special operation mode. Note that this is not atomic.
if (!data)
{
// Special path: search thread_id without pointer information
for (u32 i = 1; i <= UINT16_MAX; i++)
if (!s_cond_sema)
{
return false;
}
// Special path: search thread_id without pointer information
for (u32 i = 1; i < (s_cond_max + 1) * 64; i++)
{
if ((i & 63) == 0)
{
for (u64 bits = s_cond_bits[i / 64]; bits; bits &= bits - 1)
{
utils::prefetch_read(s_cond_list + i + std::countl_zero(bits));
}
}
if (!s_cond_bits[i / 64])
{
i |= 63;
continue;
}
if (~s_cond_bits[i / 64] & (1ull << i))
{
continue;
}
const auto cond = s_cond_list + i;
const auto [old, ok] = cond->ptr_ref.fetch_op([&](u64& val)