On 28/03/2018 16:16, Alexandre Belloni wrote: > On 28/03/2018 at 15:03:11 +0200, Daniel Lezcano wrote: >> On 28/03/2018 12:29, Alexander Dahl wrote: >>> Hello Daniel, >>> >>> Am Dienstag, 27. März 2018, 13:30:22 CEST schrieb Daniel Lezcano: >>>> Can you can give a rough amount for the irq rate on the timer ? >>> >>> I used itop [1] now to get a rough estimate. First with kernel >>> v4.14.29-rt25 >>> (fully preempt RT): >>> >>> INT NAME RATE MAX >>> 19 [ vel tc_clkevt] 397 Ints/s (max: 432) >>> 26 [ vel eth0] 4 Ints/s (max: 38) >>> >>> Next test with kernel v4.15.13 gives (slightly slower, but non-RT): >>> >>> INT NAME RATE MAX >>> 19 [ vel tc_clkevt] 248 Ints/s (max: 273) >>> 26 [ vel eth0] 4 Ints/s (max: 11) >>> >>> With kernel v4.16-rc7 plus this patch series and tcb as clocksource: >>> >>> INT NAME RATE MAX >>> 17 [vel timer@fffa] 2164 Ints/s (max: 2183) >>> 26 [ vel eth0] 5 Ints/s (max: 10) >>> >>> Is this the information you wanted? If not, could you point me on how to >>> get >>> the requested irq rate? >> >> It is perfect. Thanks! >> >> It confirms what I was worried about: the clocksource wraps up too >> quickly thus raising an interrupt every 400us. That is why I asked >> Alexande about a prescalar register. >> > > The code should behave exactly the same between the previous and the new > driver. The interrupt is not coming from the clocksource but from the > clockevent and it is already on the slowest clock, the 32kHz one.
Do you have an explanation of why the rate is much higher ? -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
