IRQ sharing...

[Sargonone]

I have yet to find a document that explains the "irq
sharing" that occurs in win2k. I think win2k is an
excellent product, however, lumping my nic/vid/sound on
one IRQ just because it lost count of the 3 more available
drives me nuts. Also, HOW does this thing work, I
understand the cascading interupts, but with shares are
you not losing performance as say 3 or 4 devices are
all "sharing" the same "hey I am done, send me another
block" or "hey, um, your going to be getting some really
crappy looking video since I grabbed the PCI bus for
transmition of many blocks of EIDE HDD data, and since my
owner was too dumb to own scsi, I am going to be sucking
up processor time and the PCI bus, and oh yea that
interupt too...

DOES not anyone know how this thing really works? I am
prepared to just do away with it and set the irq's myself,
after all God did bless me and I think I can keep that
many irq's in my head. PLEASE if anyone knows of a MS doc
that details this process PLEASE let me know, I want to
know how much KBPS im losing and just how MS figured they
would get the performance out of it too.

 

[Leonard Severt [MSFT]]

I have yet to find a document that explains the "irq
sharing" that occurs in win2k. I think win2k is an
excellent product, however, lumping my nic/vid/sound on
one IRQ just because it lost count of the 3 more available
drives me nuts. Also, HOW does this thing work, I
understand the cascading interupts, but with shares are
you not losing performance as say 3 or 4 devices are
all "sharing" the same "hey I am done, send me another
block" or "hey, um, your going to be getting some really
crappy looking video since I grabbed the PCI bus for
transmition of many blocks of EIDE HDD data, and since my
owner was too dumb to own scsi, I am going to be sucking
up processor time and the PCI bus, and oh yea that
interupt too...

DOES not anyone know how this thing really works? I am
prepared to just do away with it and set the irq's myself,
after all God did bless me and I think I can keep that
many irq's in my head. PLEASE if anyone knows of a MS doc
that details this process PLEASE let me know, I want to
know how much KBPS im losing and just how MS figured they
would get the performance out of it too.

This IRQ sharing is part of the PCI standard not a software thing. It
does not cause any loss of performance. With a ACPI BIOS you will not be
able to assign the IRQ's yourself.


http://www.intel.com/support/motherboards/desktop/sb/cs-002852-prd36.htm

Leonard Severt

Windows 2000 Server Setup Team

 

[Bob I]

In a nutshell all those "IRQs" are virtual. The standard PCI bus has 4
hardware IRQ lines A, B, C, and D. and they all funnel into a SINGLE pin
on the CPU. Now if you have a "device" that hogs the PCI bus AND does
not provide any setting to make it play nice then you GET RID OF THE
PEICE OF JUNK and go with a different product.

 

[Jetro]

General Description of IRQ Sharing in Windows 2000
http://support.microsoft.com/default.aspx?scid=kb;[LN];252420

 

[Rick]

Better yet, if your system bios allows it, disable ACPI and do a
fresh reinstall of Windows. This will give you at least some
manual control over IRQ assignment (it will assign based on
PCI slot location and onboard hardware, the same way older
systems did).

Rick

 

[georg]

Is there any way of disabling ACPI without reinstalling the
operating system?

 

[Rick]

Yes and no. There's an unsupported procedure to do this,
which entails some hardcore registry hacks (basically clearing
everything out under Enum), and most of the time people wind
up with nice big unrecoverable blue screens the first time they
try and reboot.

It's much better to do a clean reinstall.

Rick