-
IT café
Új hozzászólás Aktív témák
-
#1461
Malibutomi
nagyúr
Malibutomi
nagyúr
Ez meg szerintem nem volt. [link]
Eleg jo topic anantechen sok infoval, ez a hozzaszolas is onnan van:I did some 3D testing and eventhou there is not nearly enough data to confirm it, I'd say the SMT regression is infact a Windows 10 related issue.
In 3D testing I did recently on Windows 10, the title which illustrated the biggest SMT regression was Total War: Warhammer.All of these were recorded at 3.5GHz, 2133MHz MEMCLK with R9 Nano:
Windows 10 - 1080 Ultra DX11:
8C/16T - 49.39fps (Min), 72.36fps (Avg)
8C/8T - 57.16fps (Min), 72.46fps (Avg)Windows 7 - 1080 Ultra DX11:
8C/16T - 62.33fps (Min), 78.18fps (Avg)
8C/8T - 62.00fps (Min), 73.22fps (Avg)At the moment this is just pure speculation as there were variables, which could not be isolated.
Windows 10 figures were recorded using PresentMon (OCAT), however with Windows 7 it was necessary to use Fraps.Meg ez is:
Windows load-balances the cores, so the heavy-hitter threads are being moved around between differing cores (but not the SMT thread on the same core) every 10ms or so (Windows kernel scheduling interrupt interval). As was mentioned, you're seeing an average over 0.5 second or more, so it will appear that no core is being fully utilized - but they are... momentarily.
This process, though, makes a few issues with Ryzen.
1. It effectively prevents 'AI' prefetch adaptation
- so 10~15% of its total performance is lost right there (if AMD is to be believed)2. It shuffles data across CCXes about 50% of the time.
- This damages data locality and causes new fetches from memory.[ Szerkesztve ]
