From 096366ead51345bcd170e31b6160b14aaf73e996 Mon Sep 17 00:00:00 2001 From: Fernando Sahmkow Date: Tue, 23 Nov 2021 03:29:00 +0100 Subject: [PATCH] Common: improve native clock. --- src/common/uint128.h | 5 +++++ src/common/x64/native_clock.cpp | 40 ++++++++++++++++----------------- src/common/x64/native_clock.h | 13 +++++------ 3 files changed, 29 insertions(+), 29 deletions(-) diff --git a/src/common/uint128.h b/src/common/uint128.h index f890ffec2..199d0f55e 100644 --- a/src/common/uint128.h +++ b/src/common/uint128.h @@ -30,6 +30,10 @@ namespace Common { #else return _udiv128(r[1], r[0], d, &remainder); #endif +#else +#ifdef __SIZEOF_INT128__ + const auto product = static_cast(a) * static_cast(b); + return static_cast(product / d); #else const u64 diva = a / d; const u64 moda = a % d; @@ -37,6 +41,7 @@ namespace Common { const u64 modb = b % d; return diva * b + moda * divb + moda * modb / d; #endif +#endif } // This function multiplies 2 u64 values and produces a u128 value; diff --git a/src/common/x64/native_clock.cpp b/src/common/x64/native_clock.cpp index 1b7194503..427a382cd 100644 --- a/src/common/x64/native_clock.cpp +++ b/src/common/x64/native_clock.cpp @@ -5,7 +5,6 @@ #include #include -#include "common/atomic_ops.h" #include "common/uint128.h" #include "common/x64/native_clock.h" @@ -65,8 +64,10 @@ NativeClock::NativeClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequen u64 rtsc_frequency_) : WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, true), rtsc_frequency{ rtsc_frequency_} { - time_point.inner.last_measure = FencedRDTSC(); - time_point.inner.accumulated_ticks = 0U; + TimePoint new_time_point{}; + new_time_point.last_measure = FencedRDTSC(); + new_time_point.accumulated_ticks = 0U; + time_point.store(new_time_point); ns_rtsc_factor = GetFixedPoint64Factor(NS_RATIO, rtsc_frequency); us_rtsc_factor = GetFixedPoint64Factor(US_RATIO, rtsc_frequency); ms_rtsc_factor = GetFixedPoint64Factor(MS_RATIO, rtsc_frequency); @@ -76,34 +77,31 @@ NativeClock::NativeClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequen u64 NativeClock::GetRTSC() { TimePoint new_time_point{}; - TimePoint current_time_point{}; - - current_time_point.pack = Common::AtomicLoad128(time_point.pack.data()); + TimePoint current_time_point = time_point.load(std::memory_order_acquire); do { const u64 current_measure = FencedRDTSC(); - u64 diff = current_measure - current_time_point.inner.last_measure; + u64 diff = current_measure - current_time_point.last_measure; diff = diff & ~static_cast(static_cast(diff) >> 63); // max(diff, 0) - new_time_point.inner.last_measure = current_measure > current_time_point.inner.last_measure - ? current_measure - : current_time_point.inner.last_measure; - new_time_point.inner.accumulated_ticks = current_time_point.inner.accumulated_ticks + diff; - } while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack, - current_time_point.pack, current_time_point.pack)); + new_time_point.last_measure = current_measure > current_time_point.last_measure + ? current_measure + : current_time_point.last_measure; + new_time_point.accumulated_ticks = current_time_point.accumulated_ticks + diff; + } while (!time_point.compare_exchange_weak( + current_time_point, new_time_point, std::memory_order_release, std::memory_order_acquire)); /// The clock cannot be more precise than the guest timer, remove the lower bits - return new_time_point.inner.accumulated_ticks & inaccuracy_mask; + return new_time_point.accumulated_ticks & inaccuracy_mask; } void NativeClock::Pause(bool is_paused) { if (!is_paused) { - TimePoint current_time_point{}; TimePoint new_time_point{}; - - current_time_point.pack = Common::AtomicLoad128(time_point.pack.data()); + TimePoint current_time_point = time_point.load(std::memory_order_acquire); do { - new_time_point.pack = current_time_point.pack; - new_time_point.inner.last_measure = FencedRDTSC(); - } while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack, - current_time_point.pack, current_time_point.pack)); + new_time_point = current_time_point; + new_time_point.last_measure = FencedRDTSC(); + } while (!time_point.compare_exchange_weak(current_time_point, new_time_point, + std::memory_order_release, + std::memory_order_acquire)); } } diff --git a/src/common/x64/native_clock.h b/src/common/x64/native_clock.h index 30d2ba2e9..e57446cb9 100644 --- a/src/common/x64/native_clock.h +++ b/src/common/x64/native_clock.h @@ -3,6 +3,7 @@ #pragma once +#include #include "common/wall_clock.h" namespace Common { @@ -28,13 +29,9 @@ public: private: u64 GetRTSC(); - union alignas(16) TimePoint { - TimePoint() : pack{} {} - u128 pack{}; - struct Inner { - u64 last_measure{}; - u64 accumulated_ticks{}; - } inner; + struct alignas(16) TimePoint { + u64 last_measure{}; + u64 accumulated_ticks{}; }; /// value used to reduce the native clocks accuracy as some apss rely on @@ -42,7 +39,7 @@ private: /// be higher. static constexpr u64 inaccuracy_mask = ~(UINT64_C(0x400) - 1); - TimePoint time_point; + std::atomic time_point; // factors u64 clock_rtsc_factor{}; u64 cpu_rtsc_factor{};