[Dev] Tizen use of FIFO & Nice

Ramasamy Kannan ram.kannan at samsung.com
Fri Dec 13 03:20:32 GMT 2013

There are performance issues with the current sensor framework architecture, like generating a thread in the sensor server each time sensor data is required. We have fixed this in the new architecture that will be released for 3.0. In the new architecture there is a single event queue that delivers all the sensor events from the sensor plugins to the sensor clients. 

Here are some sensor event interval requirements for different applications.
Gaming -20ms
User Interface - 50ms
GPS - 100ms

Some indoor navigation GPS applications need to be very accurate interms of calculating the position of the mobile device. So they may go for lower sensor event intervals.


------- Original Message -------
Sender : Rusty Lynch<rusty.lynch at intel.com> 
Date   : Dec 13, 2013 01:38 (GMT+05:30)
Title  : Re: [Dev] Tizen use of FIFO & Nice

This isn't going through the sensor framework.

On Thu, 2013-12-12 at 20:01 +0000, Clark, Joel wrote:
> For IVI, we are expecting several thousand sensor updates per second, with nearly 200 different types of sensor data.  Think about data on the engine, transmission, wheels, brakes, windows, doors, seats, radar updates on proximity, etc. 
> Regards
> Joel
> -----Original Message-----
> From: Kok, Auke-jan H [mailto:auke-jan.h.kok at intel.com] 
> Sent: Thursday, December 12, 2013 11:35 AM
> To: Clark, Joel
> Cc: dev at lists.tizen.org
> Subject: Re: [Dev] Tizen use of FIFO & Nice
> On Thu, Dec 12, 2013 at 9:38 AM, Clark, Joel <joel.clark at intel.com> wrote:
> > Why does Tizen use FIFO and NICE?  There are more than 500 threads 
> > with FIFO and NICE affecting the performance of critical elements for 
> > reading sensor data and updating location etc.
> Mostly to prioritize screen update refresh rates. Do you really need your GPS location to update within a 20ms interval?
> Humans can see a single frame drop, easily. Audio is critical too.
> Sensor data (apart from touch) is almost irrelevant at the scale that humans can detect.
> Also, even with Nice values set high, applications can still be low latency. They do not necessarily conflict.
> Auke
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