Kernel Timer Frequency vs Video Performance

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Kernel Timer Frequency vs Video Performance

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chrisroed
Contributor IV

We have a custom imx6 dual lite with bsp 4.9.88_2.0.0_ga bsp.  Our application is running a QT frontend and doing realtime video chat.  Obviously this makes heavy use of the IPU and VPU.

We noticed recently that the Kernel Timer in this BSP was defaulted to 100_HZ

According to kernel documention in  <linux_src>/kernel/Kconfig.hz

 

	 Allows the configuration of the timer frequency. It is customary
	 to have the timer interrupt run at 1000 Hz but 100 Hz may be more
	 beneficial for servers and NUMA systems that do not need to have
	 a fast response for user interaction and that may experience bus
	 contention and cacheline bounces as a result of timer interrupts.
	 Note that the timer interrupt occurs on each processor in an SMP
	 environment leading to NR_CPUS * HZ number of timer interrupts
	 per second.

 

 

The documentation goes into detail about 250HZ and 300HZ being ideal for multimedia processing, and 1000HZ being ideal for desktop systems.

I'm just wondering if anyone has an insight as to whether this makes a difference in the imx6, and if changing the kernel timer has any effect on the IPU/VPU performance

 

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igorpadykov
NXP Employee
NXP Employee

Hi chrisroed

 

from theoretical point of view kernel timer frequency does not affect IPU/VPU performance.

 

Best regards
igor

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igorpadykov
NXP Employee
NXP Employee

Hi chrisroed

 

from theoretical point of view kernel timer frequency does not affect IPU/VPU performance.

 

Best regards
igor