I don't know - I've never gotten my head around this in all the years I've had Scope installed on my system. I plead ignorance. What is the story with PCI latency in regards to Scope board(s). How does one determine the best setting in the MOBO bios? Is it hit or miss? Pick a number and go for it? Pick the lowest number and work your way up? Roll the dice? Consult the Magic 8 Ball?
Is the correct answer dependent on other peripherals installed (like the graphics card)? Is there a utility that will help you arrive at the correct answer?
I've tried various settings over the years and never determined any of them to be better or worse than anything else. I think I generally have hovered around 64 or 128 without incident (ir so I think).
PCI latency
Re: PCI latency
Imo.It only needs to get adjusted to higher settings like 96-128 if you have lots of crashes.If not dont worry about it.
Re: PCI latency
This is an interesting read:
http://www.rainrecording.com/pro/softwa ... i-latency/
I use a program called "PCI Latency Tool" to tweak the pci latency of my system which gives me a little more "room" before the PCI overload message kicks in. I did not make any scientific measurements though. I haven't seen that message in a long time now that I think of it
http://www.rainrecording.com/pro/softwa ... i-latency/
I use a program called "PCI Latency Tool" to tweak the pci latency of my system which gives me a little more "room" before the PCI overload message kicks in. I did not make any scientific measurements though. I haven't seen that message in a long time now that I think of it
Re: PCI latency
BIOS specified PCI latency will provide a default setting for any devices that do not have a driver-specified setting (under your OS.) 128 seems to be the best in my experience, although on a modern (non-nForce based) PC I think 64 may be fine as well as long as you're not experiencing any issues.
The devices that tend to cause issues the most are wireless network adapters and video cards. In the past when PCIe was new (and during AGP) having an overly aggressive video card driver could choke your audio performance as the card was just soaking up too much system bandwidth (by not releasing the bus fast enough.) Wireless cards tend to do the same thing in an effort to maximize the amount of work they can do during their little time window.
The solution was to set the global PCI latency to something like 128 and then probe the individual devices with a PCI Latency Tool (DoubleDawg is/was popular here) and reduce the PCI latency setting of the graphics card or etc to below the Scope's setting (64 was my preference.)
This only addresses how long a device is going to tend to 'hang onto' the system bus once its IRQL is being serviced, the other side of this coin are the Deferred Procedure Calls (DPC Latency Checker gets used for this usually.) When servicing a higher IRQL priority than the next thread(s) ready to be dispatched, the current thread handler requests a DPC object and sticks it onto the queue (for the DPC calls) which will get handled when the higher priority (IRQL) tasks are taken care of and the processor drops back to DPC/Dispatch level of events. Ie, if you're seeing high DPC latency "spikes" this is also an indicator that a driver/device is 'not playing well' in terms of low latency handling of system events which would include your ASIO buffer and Scope environment. Typically the best solution for the worst offenders (wireless etc) is to either disable them, try a different driver or replace them altogether.
IRQ sharing complicates this process a bit as well...
The devices that tend to cause issues the most are wireless network adapters and video cards. In the past when PCIe was new (and during AGP) having an overly aggressive video card driver could choke your audio performance as the card was just soaking up too much system bandwidth (by not releasing the bus fast enough.) Wireless cards tend to do the same thing in an effort to maximize the amount of work they can do during their little time window.
The solution was to set the global PCI latency to something like 128 and then probe the individual devices with a PCI Latency Tool (DoubleDawg is/was popular here) and reduce the PCI latency setting of the graphics card or etc to below the Scope's setting (64 was my preference.)
This only addresses how long a device is going to tend to 'hang onto' the system bus once its IRQL is being serviced, the other side of this coin are the Deferred Procedure Calls (DPC Latency Checker gets used for this usually.) When servicing a higher IRQL priority than the next thread(s) ready to be dispatched, the current thread handler requests a DPC object and sticks it onto the queue (for the DPC calls) which will get handled when the higher priority (IRQL) tasks are taken care of and the processor drops back to DPC/Dispatch level of events. Ie, if you're seeing high DPC latency "spikes" this is also an indicator that a driver/device is 'not playing well' in terms of low latency handling of system events which would include your ASIO buffer and Scope environment. Typically the best solution for the worst offenders (wireless etc) is to either disable them, try a different driver or replace them altogether.
IRQ sharing complicates this process a bit as well...
Re: PCI latency
Wow thanks for explaining it. Based on that Rain Recording link, I guess I'm ok if I just stick with 64 and let it be huh? I'm not necessarily experiencing anything bad that I think would be BIOS related but I had been thinking about it recently and poking around and started wondering if I was doing all I could be to tweak my system for optimum performance. Should probably just learn to leave well-enough alone I'll take a look at those utilities and see if they tell me anything meaningful. Thanks!
PS Double Dawg doesn't seem to be available any more. Or is it?
I'll take a look at those utilities and see if they tell me anything meaningful. Thanks!PS Double Dawg doesn't seem to be available any more. Or is it?
Re: PCI latency
Pretty sure I have it somewhere. If it can't be found online, drop me a PM & I'll look for it.
Re: PCI latency
I use PCI Latency Tool. Google.