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Re: Nt and device interrupts
OSR_Community_User
Member Posts: 110,217
in NTDEV
[email protected] said:
> What is a latency when my device interrupting and my driver start to
> service it. Now my driver start service it when time elapsed 148 us.
> That sounds very long time.
That is consistent with NT performance as I tend to see it. There is
really nothing you can do to speed up the time between interrupt to the
hardware and NT calls your ISR, you are stuck. You may want to check
if there are any other devices sharing your interrupt (PCI, right?)
and if so you may be able to correct that by shuffling cards a bit,
but I doubt it.
Also, I hear second hand (sorry, no references) that interrupts are
slower on SMP machines, but not by an order of magnitude.
I've attained 10X interrupt latency improvements (as measured by an
oscilloscope on INTA#) by replacing NT with Linux, but that is of
little use if you are selling into the Windows world.
The short of it is that I've learned to not design hardware that has
real-time latency requirements.
--
Steve Williams "The woods are lovely, dark and deep.
[email protected] But I have promises to keep,
[email protected] and lines to code before I sleep,
http://www.picturel.com And lines to code before I sleep."
> What is a latency when my device interrupting and my driver start to
> service it. Now my driver start service it when time elapsed 148 us.
> That sounds very long time.
That is consistent with NT performance as I tend to see it. There is
really nothing you can do to speed up the time between interrupt to the
hardware and NT calls your ISR, you are stuck. You may want to check
if there are any other devices sharing your interrupt (PCI, right?)
and if so you may be able to correct that by shuffling cards a bit,
but I doubt it.
Also, I hear second hand (sorry, no references) that interrupts are
slower on SMP machines, but not by an order of magnitude.
I've attained 10X interrupt latency improvements (as measured by an
oscilloscope on INTA#) by replacing NT with Linux, but that is of
little use if you are selling into the Windows world.
The short of it is that I've learned to not design hardware that has
real-time latency requirements.
--
Steve Williams "The woods are lovely, dark and deep.
[email protected] But I have promises to keep,
[email protected] and lines to code before I sleep,
http://www.picturel.com And lines to code before I sleep."
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