On 07/12/2017 21:36, Benjamin Gaignard wrote: > 2017-12-07 17:49 GMT+01:00 Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>: >> On 07/12/2017 17:33, Benjamin Gaignard wrote: >>> 2017-12-07 16:27 GMT+01:00 Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>: >>>> On 14/11/2017 09:52, Benjamin Gaignard wrote: >>>>> The clock driving counters is at 90MHz so the maximum period >>>>> for 16 bis counters is around 750 ms which is a short period >>>>> for a clocksource. >>>> >>>> Isn't it 728us ? >>> >>> yes it is: 2^16 / 90.000.000 => 728us >> >> Ok, now I can do the connection with the previous patch. >> >> So, the real issue of all this is the 16bits clocksource is wrapping up >> every 728us, hence the clockevent periodically expires every ~728us to >> keep the timekeeping consistent. Unfortunately, the kernel has a too >> high overhead for this as the system is consistently processing this >> timer leading to a CPU time resource starvation. >> >> Is that correct ? > > Yes that is correct Oh man. That was unclear since the beginning, we are not talking about inaccurate clocksource or whatever but just these 16bits timers can't work on Linux. -- <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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
