Kosta, This kernel and older ones include device drivers which use threaded IRQs (call request_threaded_irq(), etc). For example, many of the driver under drivers/input/touchscreen are using threaded IRQs: Following link is from kernel 3.18: http://lxr.free-electrons.com/source/drivers/input/touchscreen/ucb1400_ts.c?v=3.18 How did you came to the conclusion that this kernel does not support threaded IRQs ? could it be that you simply do not use device drivers that use this mechanism ? Regards, Rami Rosen http://ramirose.wix.com/ramirosen On 13 September 2015 at 09:24, Kosta Zertsekel <zertsekel@xxxxxxxxx> wrote: >>> I think I get the pro of using threaded interrupts - to decrease the >>> maximum >>> interrupt latency on RT workloads and/or RT machines (servers, embedded, >>> etc.). >>> So, I'd like to ask: >>> - Why not **all** of the drivers use the threaded interrupts? >>> - What are the cons of the threaded interrupts? >>> >> Just a wild assumption: maybe the cost of incurring context switches ? >> (comparing to tasklets) > > I get that threaded IRQ is better than softIrqs because threaded IRQ > supports > priorities. On the other hand, added context switches surely get system > slower. > But from the practical point of view - why on relatively new Intel PC there > are > no threaded irqs at all? > > ``` > $ uname -a > Linux kostaz-OptiPlex-7010 3.19.0-26-generic #28-Ubuntu SMP Tue Aug 11 > 14:16:32 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux > ``` > > --- KostaZ > > On Thu, Sep 10, 2015 at 11:09 PM, Rami Rosen <roszenrami@xxxxxxxxx> wrote: >> >> Kosta, >> >> Just a wild assumption: maybe the cost of incurring context switches ? >> (comparing to tasklets) >> >> Best Regards, >> Rami Rosen >> http://ramirose.wix.com/ramirosen >> >> >> >> On 10 September 2015 at 20:49, Kosta Zertsekel <zertsekel@xxxxxxxxx> >> wrote: >> > Hi guys, >> > >> > I hope I'm on right mailing list. :-) >> > I think I get the pro of using threaded interrupts - to decrease the >> > maximum >> > interrupt latency on RT workloads and/or RT machines (servers, embedded, >> > etc.). >> > >> > Also, I see that in 4.2 there are only ~76 drivers that use threaded >> > interrupt: >> > ``` >> > $ git grep -l IRQ_WAKE_THREAD | sort | grep -v "\.h" | wc -l >> > 76 >> > ``` >> > >> > So, I'd like to ask: >> > - Why not **all** of the drivers use the threaded interrupts? >> > - What are the cons of the threaded interrupts? >> > >> > Thanks, >> > --- KostaZ >> > >> > _______________________________________________ >> > Kernelnewbies mailing list >> > Kernelnewbies@xxxxxxxxxxxxxxxxx >> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> > > > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
