<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Dec 5, 2016 at 4:35 PM, Greg KH <span dir="ltr"><<a href="mailto:greg@kroah.com" target="_blank">greg@kroah.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span class="gmail-">On Mon, Dec 05, 2016 at 04:24:05PM +0200, Ran Shalit wrote:<br>
> Hello,<br>
><br>
> We need to support serial driver with real time requirements (towards specific<br>
> device with RT demands):<br>
> Every 5.3msec receive 100 bytes and 1.3msec afterwards send 100 bytes.<br>
><br>
> 1. Does kernel support real-time of such hard requirements ?<br>
<br>
</span>It depends on the hardware you are using, does your hardware provide<br>
enough processing power and lack of harware interruptions (i.e. SMI) to<br>
allow this to work properly?<br>
<span class="gmail-"><br>
> 2. Is it matter if we do the exact bytes send/receive from kernel or userspace,<br>
> i.e. is kernel more real-time than userspace ?<br>
<br>
</span>It depends on your userspace code, people write real-time Java code in<br>
userspace just fine.<br>
<span class="gmail-"><br>
> 3. Is mainline kernel unable to support such requirements and we better use RT<br>
> patch such as xemonai ?<br>
<br>
</span>Why not try it out yourself and see? You have the code and the hardware<br>
to test, you don't need us to tell you if this works or not :)<br></blockquote><div><br></div><div>Hi,</div><div><br></div><div>I mean that the requirements doesn't allow missing of these time intervals for send/receive.</div><div>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) ?</div><div> </div><div>I also wanted to ask if it is doing real-time in kernel is better than doing it in userspace ?</div><div><br></div><div><div>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. </div></div><div><br></div><div><br></div><div>Thank you for any feedback.</div><div>Ran</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
good luck!<br>
<br>
greg k-h<br>
</blockquote></div><br></div></div>