On Mon, Dec 5, 2016 at 4:35 PM, Greg KH <greg@xxxxxxxxx> wrote:
On Mon, Dec 05, 2016 at 04:24:05PM +0200, Ran Shalit wrote:
> Hello,
>
> We need to support serial driver with real time requirements (towards specific
> device with RT demands):
> Every 5.3msec receive 100 bytes and 1.3msec afterwards send 100 bytes.
>
> 1. Does kernel support real-time of such hard requirements ?
It depends on the hardware you are using, does your hardware provide
enough processing power and lack of harware interruptions (i.e. SMI) to
allow this to work properly?
> 2. Is it matter if we do the exact bytes send/receive from kernel or userspace,
> i.e. is kernel more real-time than userspace ?
It depends on your userspace code, people write real-time Java code in
userspace just fine.
> 3. Is mainline kernel unable to support such requirements and we better use RT
> patch such as xemonai ?
Why not try it out yourself and see? You have the code and the hardware
to test, you don't need us to tell you if this works or not :)
Hi,
I mean that the requirements doesn't allow missing of these time intervals for send/receive.
Say If I'll test and it shall work OK, does it mean that in a more loaded usage (more threads in a future application), it shall still function correctly with the same kernel (from mainline) ?
I also wanted to ask if it is doing real-time in kernel is better than doing it in userspace ?
Since we have some doubts if kernel can support such hard requirements, I raised this question. I know that Xenomai was created to make kernel hard real-time.
Thank you for any feedback.
Ran
good luck!
greg k-h
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