Windows: Line-Based vs. Message Signaled-Based Interrupts. MSI tool.

Without or with Overclocking .. take this notice
Don't use MSI mode for nvidia card on Desktop computers because it effect the clock time, it mess up something in the driver. I've never had any issue with any of the drivers till I enabled MSI mode the last time which caused the GPU Clock when I left it Idle for a long time to be stuck on 670 mhz and max was 789 mhz, changing the memory or gpu clock using Nvidia Inspector brought the Clock back to full after closing Nvidia Inspector but game felt laggy till I did a restart. So using DDU just to be sure and not using MSI even when overclocking more now the issue doesn't happen anymore.


For some weird reason MSI is enabled for both ATI and Nvidia cards on Laptops. but ATI has MSI enabled on desktop too, can't be sure why. I wish someone could ask nvidia why.

 

i change my gpu to msi mode with every drivers change and have done so for few years and my gpu clock down to idle speeds just fine on all drivers short of the bug being the drivers them selves, that and the last 3 nvidia drivers have had the bug where max performance in global would never downclock to idle speeds in windows 10 fix, cause even max performance in global now down clocks to the correct idle speeds in msi mode.

 

Why when i change network adapter to MSI mode it doesn't work? It looks like this

h_ttp://scr.hu/2ykh/ts0vv (remove _ between http)

And when i tick atheros l1 gigabite, it doesnt work. Windows says "No internet acces" What can i do?

 

If device stops working after you switch it to MSI mode, you can do nothing. Just revert it to mode in which it works.

 

okey @mbk1969

I've got a some question though ;D.

Cuz when i use this msimode tool to all devices on my computer i feel less input lag on games and games run "smoother". This is awesome good. And my question is:

Have you got more tips to decrease input lag, dpc latency, to got more smoothers games etc? I read on this thread : h_ttp://forums.guru3d.com/showthread.php?t=405360&page=9 (delete _ between http)

This tool will help, some users write they got better perfmormance in some games. Have you got download link to this tool (cuz site needed login and password :/)

And i also tried HPET but only in windows cuz i haven't got this option in bios.. My moobo is asus p5e vm se.

On nvidia i use Display - no scaling (less input lag i read it somewhere) Have you got some tools/tweaks/tricks, something to get better performance/less input lag?

 

I tried MSI mode back when I was still on Windows 8.1 for a little while and noticed no difference at all. Then again my GPU is only shared with a USB 2.0 controller which I have nothing plugged into so that's not really a surprise. In fact in a few benchmarks that I ran performance actually decreased slightly compared to running it in the default line-based mode. It was by a very small amount, possibly not statistically significant. I also noticed that in LatencyMon when using MSI mode the (I think) directx kernel driver stopped causing interrupts (in comparison to line based mode where it would). Any explanation as to what's going on there?

I was under the impression that with PCI-E line-based interrupts basically act like MSI when you peel away the compatibility stuff (as in there's not really an interrupt line anymore). It may be that this mode winds up being faster for Nvidia's cards on Windows (or at the very least is the better mode for some other less obvious reasons). It seems silly to think that they wouldn't be using the best mode available to them since they apparently have a choice given that MSI mode appears to work.

I just find it hard to believe they would be deliberately crippling their cards by using an inferior interrupt mode. I don't really think there's that much solid evidence in this thread other than a lot of "feels" posts which don't really offer much. I'm not saying there may not be certain cases where it's beneficial but for most I think you're better off leaving it alone.

Don't mess with the HPET settings, Windows will automatically use the best available combination and has done for several Windows versions now.

You also want to leave display scaling to the default setting as changing it to "no scaling" or whatever the option is may actually increase input latency[1].

That may have been a bug and was fixed but again there's not really a reason to change it from default either unless you somehow require some other scaling mode.

Another comment from that esreality thread also makes a good point[2].

[1] http://esreality.com/post/2640619/input-lag-tests-ql-csgo/
[2] http://esreality.com/post/2640619/input-lag-tests-ql-csgo/#pid2640890

 

I did not test it.

As TheRyuu said do not touch HPET. This advice is good in general, but modern PC rig plus modern PC OS can have so many combination of nuances so you better try it yourself. It can be that one game can benefit from HPET when other suffers.

You can try this tool
http://forums.guru3d.com/showthread.php?t=376458
On my rig I found one game (DX:HR) which stops to stutter with this tool in action.

Also you can try this tool
http://forums.guru3d.com/showthread.php?t=376458

As a general rule I recommend to minimize quantity of processes and system services executing on background.
And if you use gamer grade mouse and keyboard then do not increase polling rates too high. I suppose that values higher than 500Hz can keep CPU really busy.

Edit: And do not forget to switch power plan to performance one (at least for a game time).

 

I using already the windows timer resolution.

But you post 2x same tool (you said try also this tool, and post link to the same tool like above )

And have you got any advices to decrease dpc latency? I've got something about 150-200 us. Most causing driver is nvlddmkm.sys

Its nvidia driver i think, its any nvidia driver versions with less dpc latency or something?

MSImode to my graphic card = huge diffrence in dpc latency. DXGkrnl.sys has got a HUGE decrease on execution time, this is awesome. And i wondering is something to do with this nvlddmkm.sys :/

 

Oops...
http://forums.guru3d.com/showthread.php?t=389072

As for DPC latency, we have here hardware part, OS part and drivers part. The less hardware devices => the less device drivers => the less probability of high DPC latency. We can do nothing about drivers and OS kernel (unless you use UNIX-based OS).

 

I really question how much tools like this are needed. Stuff that needs the increased resolution will raise the timer resolution anyway. I assume the reason they exist is to raise it beyond the 1ms resolution that most programs will use (to 0.5ms) but it seems quite hard to measure the benefits of doing so (perhaps looking at consistency of frame timings in a game, fps would be pretty meaningless for this I think).

Windows 10 seems to handle the timer resolution stuff differently from previous Windows versions (for me at least). If something raises the timer resolution to 1ms Windows seems to automatically increase it to 0.5ms under certain circumstances which I believe is if something has audio. It may be happening because of my USB DAC, haven't tested anything without it.

There's nothing wrong with doing nothing and not worrying about it. Your dpc latency is after all ~150 microseconds. IMO what a normal dpc latency will be can vary widely from one computer to the next and you really shouldn't worry about it. Remember DPC latency is not the sole measure of performance for a computer.

 

It resolved some random issues that I had with audio crackling/popping and also network card crashes (Atheros AR8161 with old 2013 driver) that required rebooting PC, I knew that both sound card and network shared the same IRQ(18).
I never thought that this could be a problem with newer operating systems (Win 10), I was wrong. Everything works fine now, I also moved the mouse/kb to USB 3 which is also MSI enabled, maybe it's placebo but it seems smoother (500 Hz polling rate).

Also latency dropped to almost half in idle, lower than 50 us.

 

Hey mbk1969, thanks for the guide first of all. I was wondering if you could please take a look at my "Device Manager" picture and tell me if there is anything else you might notice under PCI that could possibly be switched over to "MSI Mode". Thank you!

 

Only High definition audio controllers.

 

Oh well those are disabled because they're my Realtek on-board audio I'm pretty sure. Does it matter since they're disabled in the BIOS?

 

I suspect that one of these HDA controller entries is for NVIDIA Geforce 970 (HDMI or DP audio), and another one is for SB Recon 3D PCIe Audio controller.

When device is disabled in BIOS it can`t be discovered by OS.

 

I believe if you don't install the audio drivers from the Nvidia driver package then it will use the generic Windows driver and show up as the same thing as your motherboard device.

 

And? Look at grizzlyyy`s post above. He thinks that device manager shows him device disabled in BIOS. I have never saw device manager showing device disabled in BIOS.

Edit: If device was disable in BIOS after it was detected by Windows then user can see it only after he set option "Show hidden devices" in device manager (and created environment variable "devmgr_show_nonpresent_devices").
If device was disable in BIOS before installing the Windows user will never see it in device manager.

Edit: And more - if device is disabled it needs no resources like IRQ, memory addresses etc.

 

I just got a new system and I tried setting most of the PCI items to MSI Mode. But this happened. Can you shed some light on this mbk1969? Should I just undo the changes and run default? It's kinda freakin me out. Also is there anything else you noticed that I might be able to set to MSI Mode that I might have missed?

 

What exactly is freaking you out? Multiple entries on network card? That means that your NIC uses more then one IRQ. That mode was meant namely for network cards. If your network is working normally then its OK. Otherwise just switch NIC back to line-mode.
By the count of IRQs per NIC I can assume that your rig has 8 core CPU with hyperthreading - one IRQ per logical processor.

One note about sound blasters - not a single user on this thread had working (Creative) sound blaster after switching it to MSI-mode.

 

Mine works fine in MSI-Mode. Soundblaster ZxR.