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

Hello,

thank you very much for this great utility. I improved with it the latencies on multiple PCs and notebooks. Yes, some devices dont work with MSI enabled but majority does and can be switched into this mode. Then the overall responsiveness increases usually, microstuttering is decreased, if not the settings can be easily reverted withín the program or by reinstalling the driver.

As for Atheros questions that were raised here, my experience is that AR8161 works very good in MSI mode both with 2.1.0.21 and 2.1.0.27 driver version. In the desktop usage in this case it is also useful to limit the number of MSIs to 1 (by default it on some computers shows up to 16 MSI max limit. If I let it be without limiting it occupies multiple "negative IRQs", which can be beneficial with other drivers (like NVMe or graphic driver). But with this particular Atheros driver I didn't see or measure any, the responsiveness didnt seem to improve with multiple IRQs for network card. This is consistent with what is in the INF file for Atheros, it does not enable MSIs by default for some card but specifies the limit in one section

[Msi.Addreg]
HKR, "Interrupt Management", 0x00000010
HKR, "Interrupt Management\MessageSignaledInterruptProperties", 0x00000010
HKR, "Interrupt Management\MessageSignaledInterruptProperties", MSISupported, 0x00010001, 0
HKR, "Interrupt Management\MessageSignaledInterruptProperties", MessageNumberLimit, 0x00010001, 1

but somehow when it gets installed (with MSI and MSIX modes seen in the utility as supported) this limit 1 is not applied in my case and there is just max number 16, so I had to add it manually and it works well.

Device PNP properties
Display name : Qualcomm Atheros AR8161 PCI-E Gigabit Ethernet Controller (NDIS 6.30)
PDO name : \Device\NTPNP_PCI0014
Driver version : 2.1.0.27
Driver inf-path : oem7.inf
Driver provider : Qualcomm Atheros
Driver rank : 16711681

Device PCI properties
PCI device type : PciExpressTreatedAsPci
PCI-E max speed : v.1
PCI-E max lanes : 1
Interrupt modes : LineBased, Msi, MsiX
Max MSI limit : 16

But some other atheros chips like AR8131, with the same driver on different PC, did not work and I had to revert the settings to line-based mode.
So Atheros drivers can be tricky but when it works it brings improvements to system responsiveness.

To sum up, it is worth trying to optimize the system with this utility, in general I gained more perceived improvements with older PCs or with PCs where there is many devices, but also on new PCs it can be used.

 

One more thing, usually the devices that have got a lot of interrupts and activity affect the responsiveness the most. On the other hand, there are some devices that can be switched into MSI mode, but are seldom used or are not used most of the time - here it is probably not important to try the MSI mode.
Generally, it is great that a state when all the sharing of line based interrupts is eliminated by switching some devices into MSI mode, and that important devices like graphic cards or storage controllers run in MSI mode, provided their drivers support this mode well and are stable in this mode.

 

I just got a new setup, installed all necessary drivers. Realtek Ethernet and AHCI Drivers are set to high priority automatically. The only thing I did was enable MSI mode for RTX 2060. Any suggestions?

 

@Warkratos

All seems fine.

 

@mbk1969, Hi, I read a few links you posted in another thread .
https://www.reddit.com/r/intel/comments/9uc03d/the_i219v_nic_on_your_new_z390_motherboard_and/
https://github.com/djdallmann/GamingPCSetup/tree/master/NETWORK

I ran the PS command "Get-NetAdapterHardwareInfo | fl" with these results.

Name : Ethernet
InterfaceDescription : Intel(R) 82579V Gigabit Network Connection
DeviceType : Conventional PCI
SegmentNumber : 0
BusNumber : 0
DeviceNumber : 25
FunctionNumber : 0
SlotNumber :
NumaNode :
PciCurrentSpeedAndMode : 0
PciExpressCurrentLinkSpeed : Unknown
PciExpressCurrentLinkWidth :
PciExpressMaxLinkSpeed : Unknown
PciExpressMaxLinkWidth :
PciExpressVersion :
LineBasedInterruptSupported : False
MsiInterruptSupported : False
MsiXInterruptSupported : False

Notice False for last three options which your tool says 82579V Gigabit Network supports both linebased and Msi modes (IRQ= -8)
My question is shouldn't Get-NetAdapterHardwareInfo | fl show lineBasedInteruptSupport True even if MsiInterruptSupported is false?
I mean can't have all three false as that is only ways interupts work?

 

@EdKiefer

Are you sure you ran that command in elevated PowerShell?

 

Positive, I do a right click on start and use the PS with admin menu context option.

I just now tried all three ways, from the start menu, and tried also PS ISE all with admin rights, the same thing last three entries are false.

Everything is working fine, I was just reading those links and tried that PS script (Get-NetAdapterHardwareInfo | fl) to see what it produced as the one link said my card is not supported for multi RSS queues.

 

Not last 3 entries, last 9 entries are not reported.

RSS is only needed on server workloads. To spread DPCs across different CPUs user can utilize different methods.

Upd:
Here is the log from my work rig:

Code:

Get-NetAdapterHardwareInfo | fl

Name                        : WiFi
InterfaceDescription        : Intel(R) Dual Band Wireless-AC 3168
DeviceType                  : PCI Express treated as PCI
SegmentNumber               : 0
BusNumber                   : 2
DeviceNumber                : 0
FunctionNumber              : 0
SlotNumber                  :
NumaNode                    :
PciCurrentSpeedAndMode      :
PciExpressCurrentLinkSpeed  : 2.5 GT/s
PciExpressCurrentLinkWidth  : 1
PciExpressMaxLinkSpeed      : 2.5 GT/s
PciExpressMaxLinkWidth      : 1
PciExpressVersion           : 1.1
LineBasedInterruptSupported : True
MsiInterruptSupported       : True
MsiXInterruptSupported      : False

Name                        : Ethernet
InterfaceDescription        : Realtek PCIe GbE Family Controller
DeviceType                  : PCI Express treated as PCI
SegmentNumber               : 0
BusNumber                   : 3
DeviceNumber                : 0
FunctionNumber              : 0
SlotNumber                  :
NumaNode                    :
PciCurrentSpeedAndMode      :
PciExpressCurrentLinkSpeed  : 2.5 GT/s
PciExpressCurrentLinkWidth  : 1
PciExpressMaxLinkSpeed      : 2.5 GT/s
PciExpressMaxLinkWidth      : 1
PciExpressVersion           : 1.1
LineBasedInterruptSupported : True
MsiInterruptSupported       : True
MsiXInterruptSupported      : True

Upd:
And that command does not require elevation...

Upd:
Note that "DeviceType : PCI Express treated as PCI" not "Conventional PCI"

 

I also checked SG TCP optimizer which uses PS for many settings and RSS was set to enabled. I just wasn't expecting those results.

also ran this.
PS C:\WINDOWS\system32> Get-SmbClientNetworkInterface

Interface Index RSS Capable RDMA Capable Speed IpAddresses Friendly Name
--------------- ----------- ------------ ----- ----------- -------------
13 False False 1 Gbps {fe80::b19b:ef6a:5f9f:5a59, 69.116.236.152} Ethernet
9 False False 0 bps {fe80::31bc:e4b2:ea8b:cc3d} Wi-Fi 2

Then
PS C:\WINDOWS\system32> Get-NetAdapterRSS

Name : Ethernet
InterfaceDescription : Intel(R) 82579V Gigabit Network Connection
Enabled : True
NumberOfReceiveQueues : 1
Profile : Closest
BaseProcessor: [Group:Number] : 0:0
MaxProcessor: [Group:Number] : 0:3
MaxProcessors : 4
RssProcessorArray: [Group:Number/NUMA Distance] : 0:0/0 0:1/0 0:2/0 0:3/0
IndirectionTable: [Group:Number]

So here it shows it is True, anyway thanks for help, this is a ASUS P8- Z77V Pro MB.

 

@EdKiefer

assuming you're using an intel platform with an intel pch, the ethernet controller is on a pcie-like interface dedicated to the 82579, thats why the powershell can't get PCIE information for it, this includes the MSI info.


Regardless what the powershell is saying, the device natively supports MSI's and should use them by default.

The second bit of the quote refers to the fact a second 82579 can be implemented in the system (Dual Lan) as well as on non intel platform usage, for which i've seen later 825xx on a few AMD boards.

 

Ahh, I see, well that makes sense then, Yes This is an Intel 3570k in a ASUS P8Z77v pro mb and the NIC is onboard one.
It is with IRQ -8 which was with default msi mode from the driver (I didn't have to enable it).

 

Might be too much of an ask but is it possible to get a copy of the source code?

I was thinking of looking into adding some command line functionality to grant the ability to set turn msi on, for specific devices on boot if it wasnt already configured. Figured this would be a easy enough way to get that functionality.

 

On boot of what - OS or app?
I don`t get the meaning of your feature. Can you describe it step by step?

PS If you just want to turn MSI mode for all devices (in bulk) I can give you link to PowerShell script. I just removed it to not endanger users with unbootable OS.

 

I wouldnt mind a powershell script. Here is my situation. I am running a windows 10 vm passing through a video card and usb controller etc. My goal was to set most if not all devices to MSI mode and give a prompt to let me know if it needed to set any device to MSI mode since my understanding is a restart is likely required to have Message signal based interrupts to work. so turning on all devices in bulk would probably be just fine since I enabled it for all the devices anyways.

What I was thinking with the application was just to have a command line argument you set so I could make a task that launched at startup doing this but if you are willing to send a powershell script that would be greatly appreciated. Thank you

 

https://www.mediafire.com/file/rcgtxc73fp00x26/MSI_mode_utils.zip/file

It requires elevation. So you should create task with privileges (with privileged account).
In case you are not familiar with PowerShell, when executed without input parameter script prints all devices with MSI mode turned On/turned Off/not configured. To turn MSI mode On execute script with parameter "on"/to turn MSI mode Off - with "off"/to generate text of reg-file with current state of registry values related to MSI mode - with "reg".

 

Thank you this is much appreciated. It is exactly what I wanted.

 

Just to add my 2 cents here as well. Recently I've found out that some apps don't detect my CUDA cores. (GTX 1080ti) and it turns out that it's most probably because I switched to MSI mode. (also OpenCL and PhysX)



I came to this conclusion by personal experience and also by a quick search where I found this (I know it's about Linux, but I guess it kinda affects Windows as well):
Message Signaled Interrupts? | NVIDIA GeForce Forums

GPU performances seemed to be ok in games, but for example I couldn't enable the CUDA rendering for Adobe Premiere Pro because of that. So keep that in mind unless you have a suggestion on how to enable it and still have them detected?

In addition a question. Is the bottom(last) Audio Controller ok to have the same irq as the GTX 1080 ti, because it's the audio from the nvidia drvier or am I in the wrong here? Do you see anything I should (try) change here? Thank you!

 

entirely unrelated

 

NVIDIA videocard and High Definition Audio controller sharing IRQ is not good, but if you do not output audio through videocard the problem is small. But I see another device using same "IRQ 16". Also I see two completely unrelated devices sharing "IRQ 17". I would switch all capable devices to MSI mode.

 

Actually I switched everything except of the Synaptic SMBus Driver and the CUDA, PhysX and everything else seems ok. Not sure what bugged before, might be because of multiple stuff combined. I like trying out things. Bad part is when you don't notice something broke
So I guess it was a combination of things and Windows. As always, thanks for your effort and help!