IRQ16 list from my Win 10 Pro system
High Definition Audio Bus
NEC PCI to USB Open Host Controller
Texas Instruments 1394 OHCI Compliant Host Controller
Standard Enhanced PCI to USB Host Controller
 

You seem to be saying there a misunderstanding. What is that all about?
 
The APIC architecture spreads interrupt sources from various buses (e.g. PCI bus) into as many as 224 different sources, all independently vectored.  IRQ 16 is no longer a unique interrupt interrupt source. There is no polling as you seem to imply there is. Each device is directed immediately to its own interrupt routine. Moreover, it has long been a practice to defer I/O processing to DPCs, i.e. defered procecure calls, wherever it is practical. This takes the vast majority of I/O processing out of the very highest priority and puts it at a level higher than user processes, but lower than interrupt processing. It's no longer 2000 .
 

I believe you can assign irq's in win xp.// through the "device manager"/device/preferences, and going through the tabs, cannot remember all, but one does let you assign irqs of some of them.
I believe audio was usually defaulted to 7 and 10...but Not sureany more.
 
First thing is to turn off all redundant devices in bios to free up onboard devices, disable defeats in bios. 
 
Turn off coms,serial ports if not in use, and printer ports..onboard audio? and  if so wi fi?.
 
Some bios let you assign slots to irq's...but you have to read the manual as some slots share with X....
 
Then boot and check what IRQ's are showing as free in the system info, and what is used.
 
Then mark a set target, and go into the device manager to try to push the audio in proper slot to a free irq.
 
I call this making exclusive the irq for the device....so no other interrupt occurs by any shared device being paged.
 
Again not all bios or Devices allow the manual minipulation of driver irqs and such, as plug and play might take over those settings in bios if so a setting exists in bios...You might want to defeat the plug and play...to get manual control.
 
Hope it helps.
 
Best wishes.
 
 

Thanks guys, will try to catch up with some responses....
 
- I did already disable everything possible in the BIOS that wasn't needed. 
- There isn't a way in the BIOS to set interrupts at all (which I find pathetic given my 2001 DELL machine had this support and here I am using an Intel board almost 10 years newer that now doesn't have that ability?)
- There isn't a way in the BIOS to disable PnP / APIC mode.
- There is no way to alter IRQ's in W2K/XP if in APIC mode to my knowledge.
- In theory I could try to go to Standard PC mode but I am still unclear about whether this will work for dual core CPU. I read that it won't work for multi-processor machines but it wasn't entirely clear if that mean 2 physical CPU's or anything more than single core.
 
@bvideo: Are you implying there isn't any bottleneck in IRQ processing?  DPC or not, a device cannot be interrupted again before it has completed it's "ISR" routine.  The IRQ is the trigger for this unless I'm mistaken.  Either the INT lines (A-D) and/or the IRQ are still real, no matter how implemented.  If there are multiple devices (Video, Audio, PCI Bridges, Firewire Card, USB port) all on the same IRQ, and many even sharing the same INT line, that's got to be a problem as far as I can decipher so far.
 
BTW, I did notice another perplexing thing in the DevMgr view: There are two devices listed under IRQ16 that are called "Standard PCI to PCI Bridge".  These are not in any of my older machines.  What are these things??  The Firewire card is actually "on" one of these, yet also takes up an IRQ (again IRQ16).  Why are these "bridges" listed as devices?? Is this some kind of new motherboard design aspect that happened in more recent years?   (Intel G41 Chipset)
 
Sonic

SonicExplorer
...
 
@bvideo: Are you implying there isn't any bottleneck in IRQ processing?  DPC or not, a device cannot be interrupted again before it has completed it's "ISR" routine.  The IRQ is the trigger for this unless I'm mistaken.  Either the INT lines (A-D) and/or the IRQ are still real, no matter how implemented.  If there are multiple devices (Video, Audio, PCI Bridges, Firewire Card, USB port) all on the same IRQ, and many even sharing the same INT line, that's got to be a problem as far as I can decipher so far.
...
 
 
Sonic

No bottleneck. The APIC fans out the devices onto their on ISRs (interrupt service routines - the start of the interrupt servicing routines for each individual device).  These may even be serviced independently on different CPUs.
DPC or not, any device that has multiple requests within the service time of either its own interrupt handler or of DPCs servicing other higher priority devices has multiple buffers which are all then serviced completely within its next scheduled DPC. High performance devices have multiple buffers and don't require an ISR for every buffer. This is true for USB, audio, and network devices for example.
INT lines & IRQ are not directly feeding the ISRs; the APCI does.
 
Editing to say the PCI INT A-D and 8259 PIC were exhausted long ago by e.g. PC-based servers with multiple NICs, other network interface controllers, and disk controllers long ago, hence the upgraded interrupt infrastructure based on multiple APICs.

In my IRQ16 list  3 out of the 4 listed controllers are PCIe devices.
The TI 1394 OHCI Compliant Host Controller is my PCIe Firewire card
I have two PCIe 5 port USB 2.0 cards and they are the NEC PCI to USB Open Host Controller and the Standard Enhanced PCI to USB Host Controller.
 
I needed the extra USB ports and I reused the USB port expansion cards from my old PC.  One of the USB cards have my bank of 5 USB connected CD/DVD burners that I use for Audio CD burning production.  The other one only has two devices that must have USB 2.0 ports as there are only USB 3.0 and 3.1 ports on my motherboard rear I/O Panel.
 
 
 

@Fireberd, thanks for the additional info.  Notice how don't have any PCI to PCI or PCI to PCIe Bridges listed.  I must have a strange motherboard.  I'm thinking extra bridges are probably NOT a good thing for a DAW.
 
as to the other aspect under discussion......
 
APIC and Windows collaboration is still an abstraction, at the end of the day there remains IRQ's and INT lines, and they are limited and require synchronization to varying degrees.  Having too much all on the same INT line AND IRQ simply cannot be a good thing.  If anything misbehaves, device or driver, it could potentially impact the timeline of processing of other devices on that lane.  IIRC, this in fact is what often causes issues with audio and is why even today still recommended to try and keep the sound card on it's on lane.  Again, if I am completely wrong, by all means enlighten me.
 
This situation I have with the PCI Bridge "Devices" being on the same IRQ seem to indicate there is no way to cause sound devices to have anything other than IRQ16.  PCI, PCIe, changing slots, etc. No matter, all will end up on INTA IRQ16 along with some USB and onboard audio & video.
 
I already had some lockups in S5.  A few times when initially trying to setup the soundcard input/output selections in Audio options, and once while playing a song.  When I hit stop I also get a noticeable "pop".  Not sure if that's normal, need to go back to my old DAW to compare....     
 
    Sonic
 
 

I see, you claiming 2x usb cards?...why 2?...Hubs exist...eh?
 
And the manual, should expose any shared slots with devices listed...Should I say if it is shown as listed in bios...You cannot move those from the slot assign, but you might be able to disable the device that is assigned to the slot, that is on the main board as a device.
 
 
 
Now In Bios do you have a listing for, PNP OS enabled?...That would be where you disable Win control over the Bios, I imagine, if you have the feature.
 
Problem is perhaps you are using too many cards...and things on the main board...you need to recoup, rethink, and get some hubs...and remove a card here...And read the manual for shared slots with onboard devices...to get the right slots assigned that share none or one thing you can disable...and assign it...in the windows system info/ Device manager to check the irq states.
 
In Xp you can then make a bootable configuration (say you want just your audio working) in device manager..disable nic, hdmi, and other things you left on in bios...usb?...I believe even that can be disabled in device manager....So depending on your needs for X...save as a bootable config name.
 
You can make many different configs bootable...so depending on what you need to do...with whatever devices you need working, can be setup to the way you want it, with what is only needed for that processing.
 
Say you only need internet...make a bootable config with nic and audio, with usb disabled....and boot to that named config.
 
If you need usb and audio...make the config no internet, and boot to that config.
 
If you only want one boot config...turn off (disable redundant devices in device manager).
 
So, I would reduce usb cards that are doubled up on slots for no reason, when a 7 port hub can address your needs on one card..or no cards....right from the MB usb ports, frees up two slots!...usb a,b,c...the only thing different usb ports offer is speed....So perhaps a give and rob from one to get the other...
 
 
Sorry, I have not done any of the above for some time...and I had to google how to do...and so I did follow that path.
 
I found, older MB's, got issues with more than two cards put in...one video, if so, and one other, put in a slot that is best suited for it's proper functioning for, should work..but three or more, always gets the sharing happening...Manuals must be read for slot assigned irq's, and in understanding these things...(keep it as simple a setup as possible)...there are cards that have both firewire 400/800 and usb now..so one card does double duties...and that is more so to find more alternate solutions...to how you got it now?...Might be sought to do some rethinking it out, your setup and card deployment...simple setups for one or two slotted card  devices, works better with MS windows...when put in properly and assigned proper...
 
But it ain't perfect ever!....Just to say...I've been there done that!...and still got one machine working with Xg midi daughterboard on isa audio card on XP..that way...still crashes, clicks pops and gets muddled up.
 
My solution was to get off the usb, and firewire band wagon...as it did not solve my issues with MS OSes, even trying out the new thunderbolt 1 ,2, and now 3...got issues with Windows oses..and usb not working proper in win 10 and wireless keyboards and mice.
So...Best of luck ....lol
 
Cheers.
 
 

I already tried the motherboard manual.  Believe it or not there is NOTHING about slot assignment, IRQ or Interrupt tables.  And nothing in BIOS to adjust, and not even able to turn PnP on/off.  Grrrr.....  
 
I've only got the one Firewire card for the external RME Fireface, that's it.  Everything else is onboard (video and audio).

When I tried disabling the front USB ports in the BIOS, it caused the rear USB ports to become low-speed (when plugging in a flash drive received the warning from Windows about there being no high speed USB ports available) .  That makes ZERO sense to me, but that's what happened alright. Turned front USB ports back on and everything went back to full speed.  Weird.   Anyway, onboard Serial, LPT, Lan - all disabled.
 
There is no ratioanl reason for the two PCI bus/bridge "devices", and everything else, to all be on INTA IRQ16.  This must be the most lame, or Windows-unfriendly, motherboard around is all I can guess.  It's a 775 socket G41 Intel series so I never considered the board/BIOS could be a POS.  Then again, maybe this is how most boards are designed within the last 5+ years, except for some of the full-size high-end tweaker-boards like Asus and Gigabyte.
 
What kills me is there are wide OPEN INT lines AND IRQ's - but apparently no way to get the BIOS and Windows to do anything sensible together.
 
Sonic
 
 

 
https://www.microsoft.com..._dev_mgr.mspx?mfr=true
 
https://docs.microsoft.com/en-us/windows-hardware/drivers/install/device-manager-details-tab