Hi Valdis,
Device specs: CPU: 1.7Ghz & RAM: 2GB.
We are not adding any code in the mm_init, All we do is reserve some memory during the boot time and rest of the memory around 1.45GB we configure it as HIGHMEM.
Can you give me any info on how to do the profiling of the function calls during ealry booting in the kernel.
Thanks
Sandeep
On Tue, Jan 22, 2013 at 12:38 PM, <Valdis.Kletnieks@xxxxxx> wrote:
On Tue, 22 Jan 2013 11:32:19 -0800, sandeep kumar said:Oh, I could believe there's 2 seconds of time used up there that doesn't
> as you rightly mentioned,cat /proc/kmsg is showing the time stamps,
> according to that it is 0ms only.
> But when you see the same with UART there is 2sec delay in showing the next
> log. i caught this while i m observing the UART logs with
> "Terminaliranicca".
show in kernel timestamps because the timers aren't started yet.
Time for some lateral thinking.. :)
> Since i m early in the mm_init, i cant use watchdog to detect it, hrtimers
> i cant use..i am really thinking how to analyse this delay..
Can you give us some specs on the hardware (in particular, the CPU type/speed
and how much RAM is installed)? 2 seconds on a 2Ghz CPU is about 4 billion
cycles.
Also, are you adding any code into the mm_init path? If so, what exactly
are you doing?
I wonder how early the kernel tracing and profiling stuff is enabled. It may
be possible to boot a kernel that has function-call tracing enabled, which
would not have timing info, but if you see a function that's being called 500K
times that should only be called a dozen times, that's probably your problem :)
You'd probably want it with 'init=/bin/bash' and dump the stuff, as running to
multiuser will almost certainly roll the buffers and lose the info).
With regards,
Sandeep Kumar Anantapalli,
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