Discussion in 'Windows 8' started by xscess, Aug 6, 2012.
You need to login to view this posts content.
Is this good or bad? I really can't tell, I'd never even heard of DPC Latency until people reported problems with it in Windows 8.
I'm not a gamer but for gamers this may not be a good thing(but it's not that bad either, i guess), though this depends alot on graphics/audio hardware drivers etc, and drivers could improve alot by Oct 26, 2012... Espionage724 was interested in this test. If I remember correctly, on my Windows 7 installation, DPC latency was around 120/140 μs.
You should run some gaming benchmarks on the same machine with win 7 and win 8 and look at the minimum fps value to see if the dpc affects win 8, some ppl say that the softwares that we use to test dpc latency don't work well with win8 and the dlc values are wrong but i believe that win8 as of now is pure lagware; my machine runs between 46-78 μs on windows 7 while on windows 8 i get between 700 - 800 and BF3 stutters every now and then on win 8 while on win 7 runs stable
I'm using a AMD VGA with catalyst 12.6 beta and DPC latency is basically the same, around 1000,
BUT everything I tested worked smoothly, videos, audio, game (Skyrim limited to 40fps)...
on a pre RTM version I tested DPC latency and it was also around 1000 but I had problems with audio crackling not present on the RTM.
on the same PC using windows XP is much lower (it can go lower than 50, but there is some variation while on 8 it seems to be stuck at 1000)
Did some investigation.. Was averaging around 1000us at first, went into device manager, disabled everything I don't use; microphone, hdmi sound on my hdtv, usb 3.0, secondary lan, visual studio debug drivers, etc. and closed all tray items that I only use occasionally such as steam, origin, anydvd, keepass, etc. and upgraded my Asus x79 on board sound + intel lan drivers to win 8 versions from their web sites. My latency went down to around 15-20us on average, every 5-10 bars in the dpc latency checker, I'd get a green or yellow spike to 1000us, and the program said I should have no problem with audio/video. Occasionally, I could get all the bars in the window, 20+ or so, to be 15-20us if I waited a little while. I believe one of the big latency suckers was the microphone, I think it's constantly processing sound input while it's enabled and this increases the latency quite a bit, oh well don't use it anyway so I'll leave it disabled. Not sure what conclusion to draw, except if you want to lower your dpc latency in this program, do as I've done and disable useless or rarely used hardware/programs until you need them, and that Windows 8 doesn't seem too bad when you do this, though I don't know with talk that this program is not properly windows 8 aware. System is a 3930K + P9x79WS + GTX 580 + 16GB 1600mhz ram, with 7 hard drives and Blu-ray drive, plus dual monitors. I should add I was getting absolutely perfect playback of Blu-rays ripped to .mkv before hand, so wasn't really an issue any way.
DPC latency checker is designed for XP so better use LatencyMon
Win8 have this problem since DP. As a Ableton user this is not acceptable for me.
Some peculiarness occurred, dpc latency checker was showing 15-20us, but latencymon was saying 700us-900us. So...I went into services.msc, and stopped and disabled every service I don't need (a lot of LAN stuff, wmp network stuff, defender, windows search, visual studio SQL VSS service, etc.) and now latencymon says my latency is ~16us-20us and stays at that. I'd say that's quite a success, definitely disabling unnecessary services, hardware and tray apps is a good way to fix the latency for you guys who want that. I'd post pics but I have too few posts on mdl so the board doesn't all me to post links or pics.
I show a lot of it coming from the anti-malware app. I'll try disabling my microphone like the poster above suggested.
Hmm, seems latency monitor was..i dunno screwed up, it said 16us, then without anything else running, the next time I ran it, it was back to 700-900us and I can't see any cause for it. Anyway, Here's my DPC latency checker results:
Did anyone else also noticed that there's like, let's say you watch a youtube video and turning up the volume or trying to stop the video, there's like some sort of delay and it's not happening on windows 7, it doesn't happen only at youtube it happens on other players too.
Haven't noticed that black eyes, my flash videos play perfectly in IE10. Ok, one last pic, I managed to fix whatever I messed up, and now latency mon shows ~20us:
seems like it's google chrome problem, my bad.
Guys I've found out something really interesting, my DPC latency stays around 900- 950 on windows 8 while on windows 7 it's only 45-72 but i decided to run some tests and it looks like the DPC latency lowers accordingly with the sysyem load, I ran latencymon and while the test was working i also ran intel burn test and after i began the intel burn test the DPC latency went from 900 to values between 7 and 14 ! It's better than 7.
I decided to test some games and I Used Black light retribution for my test, I opened it in windowed mode and i ran latecymon in the background while I was playing I noticed that the DPC latency when I was in the lobby waiting for a match to start was still high around 300 - 400 but as soon as the match began the DPC latency went down to 7 - 14.
I also ran SF X Tekken on windows 7 I get 164 FPS while on windows 8 I get 159 FPS, the drivers are different on the two OSes it might be driver related.
The bad thing about this system is that it doesn't work with videos, I played a 1080p mkv files with FLAC audio, even though the video played just fine without dropping any frames the dpc values stayed high, the same goes when you listen FLAC files with foobar 2000.
If we could figure out a way to lock the the DPC values to the mode windows 8 uses when the system is under load it would be great
artins90: Could it be your CPU up-clocking that decreases DPC Latency? I found, that DPC Latency is 100x worse when I enable CPU down-clocking power features like EIST and C-States in the bios and measure the Latency with no load (and thus no up-clocking). Right now I can run DPC Latency Checker for 5+ minutes (too boring to run longer) and I stay under 10 μs (10 microseconds) the whole time with no load on the system, cpu down-clocking disabled and a boat load of services, scheduled tasks, as well as the page file and basically anything that hits the disk, disabled. System is still quite useable, I can play skyrim and BF3, and surf and play movies/music and do P2P..I haven't done much load testing, as I'm still trying to get the base system latency low until I'm satisfied. I have some videos of the testing I did on youtube, user name "ttewtm" (I can't post links or videos here yet) if anyone is curious.
I need the down-clocking I still have the stock cooler on my 2500k I don't want to run the cpu at 60C all day long that's why I enabled the C6 features in the bios I need to get a noctua ASAP
Keep up the good work.
Anybody tried this on Server 2012 without and with Desktop Experience?
Another nice find, doing the 'DisablePagingExecutive' reg tweak (google it and set it to 1 instead of 0) did wonders for occasional spiking I was getting. I did a 5 minute DPC Latency Checker run, and had an 'absolute maximum' of 13µs (on top of all the other tweaks I did that I've posted about above). I can readily tell that the disk is getting hit a lot less with this, thereby reducing DPC latency spikes. My memory usage didn't go up that I can see, so really no down side to applying this. Sorry dummekuehe, no server OSes to test..
DPC Latency checker is designed for XP. Plz use LatencyMon instead