推 hankower : 最後是Win10不支援SMT？！
推 ayasesayuki : 應該是支援smt讓效能更差
在此Reddit回文中往下找找到原Po的解釋:
原因是Windows 7處理Ryzen SMT的執行緒才是對的
Win 10分不出Ryzen哪個是實體核心還是SMT,
就把兩個執行緒在低執行緒負載時推給一個核心
而且Windows 10有沒有把執行緒像群組指定般處理,
移動那些緒到其他的群組核心, 把快取給浪費掉了
故AMD說他們在微軟一塊寫Win 10的更新檔
所以現在Win 10用Ryzen要得關掉SMT
AMD said they are working with MS for a Win 10 update, but it's clear,
Ryzen with SMT off is faster than on in Win 10.
But Win 7 with SMT on is faster still. O_o
Win 7's scheduler actually handles Ryzen SMT threads correctly,
and this relates to Win 10 not knowing which Ryzen thread are physical or SMT,
shoving 2 threads into 1 core when under low thread workloads...
Also potential issues with Windows 10 not treating the threads as CCX
specific, moving them to the other CCX cores, trashing the cache. :/
This is a pretty serious perf hit,
these issues should have been fixed for launch. -_-