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SubjectRe: [PATCH v3 0/6] clocksource: rework Atmel TCB timer driver
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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.



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