scheduler clock for MXS [Was: Re: Wakeup latency measured with SCHED_TRACER depends on HZ]

[Russell King - ARM Linux]

On Tue, Nov 06, 2012 at 09:49:50PM +0800, Shawn Guo wrote:
> On Tue, Nov 06, 2012 at 10:12:29AM +0000, Russell King - ARM Linux wrote:
> > > [    0.000000] sched_clock: 16 bits at 32kHz, resolution 31250ns, wraps every 20
> > > 47ms
> > 
> > So where are you setting this up?  My guess is it's after time_init()
> > has done its stuff.
> 
> It gets set up in machine_desc->timer->init() which is called right
> in time_init() just before sched_clock_postinit().

Well.  I just tried an experiment with OMAP4:

[    0.000000] sched_clock: 16 bits at 32kHz, resolution 30517ns, wraps every 1999ms                                                                            

So, this is similar to yours, and there I get:

[    1.945281] ALSA device list:
[    1.948394]   #0: SDP4430
[    1.951324] Waiting 2sec before mounting root device...
[    2.926910] kjournald starting.  Commit interval 5 seconds
[    2.927001] EXT3-fs (mmcblk1p2): warning: maximal mount count reached, running e2fsck is recommended
[    3.041503] EXT3-fs (mmcblk1p2): using internal journal
[    3.051422] EXT3-fs (mmcblk1p2): recovery complete
[    3.056427] EXT3-fs (mmcblk1p2): mounted filesystem with writeback data mode
[    3.063842] VFS: Mounted root (ext3 filesystem) on device 179:26.
[    3.070404] Freeing init memory: 192K

So it appears to be working as designed.