From 979e53b87b5288c582392beff618da978ca4152c Mon Sep 17 00:00:00 2001 From: merry Date: Sat, 2 Apr 2022 21:05:49 +0100 Subject: [PATCH] native_clock: Use writeback from CAS to avoid double-loading --- src/common/x64/native_clock.cpp | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/common/x64/native_clock.cpp b/src/common/x64/native_clock.cpp index 2a2664e5d5..7a3f21dcf1 100644 --- a/src/common/x64/native_clock.cpp +++ b/src/common/x64/native_clock.cpp @@ -55,8 +55,9 @@ 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()); do { - current_time_point.pack = Common::AtomicLoad128(time_point.pack.data()); _mm_mfence(); const u64 current_measure = __rdtsc(); u64 diff = current_measure - current_time_point.inner.last_measure; @@ -66,7 +67,7 @@ u64 NativeClock::GetRTSC() { : 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, current_time_point.pack)); /// The clock cannot be more precise than the guest timer, remove the lower bits return new_time_point.inner.accumulated_ticks & inaccuracy_mask; } @@ -75,13 +76,14 @@ 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()); do { - current_time_point.pack = Common::AtomicLoad128(time_point.pack.data()); new_time_point.pack = current_time_point.pack; _mm_mfence(); new_time_point.inner.last_measure = __rdtsc(); } while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack, - current_time_point.pack)); + current_time_point.pack, current_time_point.pack)); } }