CruNcher
24th July 2011, 08:26
I was almost going crazy (after testing Lav Splitter i realized my DXVA capabilities where gone, for those who want to read when CruNcher goes into Panic Mode and 1000 different things going through his mind ;) http://forum.doom9.org/showpost.php?p=1513808&postcount=4071 ) searching for a DXVA problem with my VP2 512MB Card and then finally i found the issue for it to be the NT 5 /3GB Kernel switch (used for Firefox Memory stability testing, works fine above 2.6 GB) :(
When it is active DXVA fails for Higher resolutions then 720p i guess it has todo with the different User/Kernel Memory mapping thus the GFX driver gets to less memory.
Maybe someone can reproduce this also on his system and the /3GB switch, the system here was a H67 Chipset (Cougar Point) with XP SP3 32 bit
PS: It seems to be like most of the times a combination of different things but it is all Memory related (DEP,PAE,/3GB), 1 thing for sure /3GB is really problematic to keep stable (impossible with full Memory allocated to Applications) in terms of DXVA it does randomly weird stuff (Green flashing in Flash Player, Ghosting, Decoder DXVA with 1080p works @ the first try then fails for another one, only 720p external of Flash Player is relative stable with /3GB and 512MB Video Memory it seems on H67, though it doesn't really surprises as i guess not even 1 Multimedia vendor and surely neither AMD/Nvidia test on XP with the /3GB switch their code as it doesn't really matter anymore with 64 bit :)
PPS: The problems can be fixed by using /USERVA="max size MB" switch and reducing the max memory pool to keep enough PTEs for the Kernel (Driver) GPU so it stays stable not sure though if this isn't the exact size that XP uses without the /3GB switch as default so you would lose win 0 i guess (Maximum limit for Applications,stable DXVA operation) (i was wrong it helps a lot) :)
So with just the /3GB switch alone you lose to much memory for the Kernel Driver GPU to keep it stable operating for DXVA (to low PTEs) :(
I experimented and found /USERVA=2990 to be a quiete stable result Firefox cycles through 200 pages without 1 crash (compared to not using /3GB) and DXVA works without issues also Flash Player behaves much better except that i need to seek when changing to 1080p before AVD sets in (though it does behave without /3GB the same way).
When it is active DXVA fails for Higher resolutions then 720p i guess it has todo with the different User/Kernel Memory mapping thus the GFX driver gets to less memory.
Maybe someone can reproduce this also on his system and the /3GB switch, the system here was a H67 Chipset (Cougar Point) with XP SP3 32 bit
PS: It seems to be like most of the times a combination of different things but it is all Memory related (DEP,PAE,/3GB), 1 thing for sure /3GB is really problematic to keep stable (impossible with full Memory allocated to Applications) in terms of DXVA it does randomly weird stuff (Green flashing in Flash Player, Ghosting, Decoder DXVA with 1080p works @ the first try then fails for another one, only 720p external of Flash Player is relative stable with /3GB and 512MB Video Memory it seems on H67, though it doesn't really surprises as i guess not even 1 Multimedia vendor and surely neither AMD/Nvidia test on XP with the /3GB switch their code as it doesn't really matter anymore with 64 bit :)
PPS: The problems can be fixed by using /USERVA="max size MB" switch and reducing the max memory pool to keep enough PTEs for the Kernel (Driver) GPU so it stays stable not sure though if this isn't the exact size that XP uses without the /3GB switch as default so you would lose win 0 i guess (Maximum limit for Applications,stable DXVA operation) (i was wrong it helps a lot) :)
So with just the /3GB switch alone you lose to much memory for the Kernel Driver GPU to keep it stable operating for DXVA (to low PTEs) :(
I experimented and found /USERVA=2990 to be a quiete stable result Firefox cycles through 200 pages without 1 crash (compared to not using /3GB) and DXVA works without issues also Flash Player behaves much better except that i need to seek when changing to 1080p before AVD sets in (though it does behave without /3GB the same way).