Can jiffies freeze?

[sandeep kumar]

Hi Mr.Valdis
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".

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..

Thanks
Sandeep

On Tue, Jan 22, 2013 at 10:40 AM, <Valdis.Kletnieks at vt.edu> wrote:

> On Tue, 22 Jan 2013 10:29:05 -0800, sandeep kumar said:
>
> > I am seeing this problem at the very early in the start_kernel-->
> > mm_init--> free_highpages, at that time nothing is up and kernel is
> running
> > in single thread.
>
> If you build a kernel with printk timestamps, you'll see that they all
> come out like this:
>
> [    0.000000] Initializing cgroup subsys cpuset
> [    0.000000] Initializing cgroup subsys cpu
> [    0.000000] Linux version 3.8.0-rc3-next-20130117-dirty (
> valdis at turing-police.cc.vt.edu) (gcc version 4.7.2 20121109 (Red Hat
> 4.7.2-9) (GCC) ) #49 SMP PREEMPT Thu Jan 17 13:25:28 EST 2013
> [    0.000000] Command line: ro root=/dev/mapper/vg_blackice-root
> log_buf_len=2M vga=893 loglevel=4 threadirqs intel_iommu=off
> LANG=en_US.UTF-8
> [    0.000000] KERNEL supported cpus:
> [    0.000000]   Intel GenuineIntel
> [    0.000000] e820: BIOS-provided physical RAM map:
> [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009bbff]
> usable
> [    0.000000] BIOS-e820: [mem 0x000000000009bc00-0x000000000009ffff]
> reserved
> (100 or so more lines with same timestamp)
> (now we finish memory init)
> [    0.000000] Dentry cache hash table entries: 524288 (order: 10, 4194304
> bytes)
> [    0.000000] Inode-cache hash table entries: 262144 (order: 9, 2097152
> bytes)
> [    0.000000] __ex_table already sorted, skipping sort
> [    0.000000] xsave: enabled xstate_bv 0x3, cntxt size 0x240
> [    0.000000] Memory: 4015936k/4718592k available (6266k kernel code,
> 536744k absent, 165912k reserved, 7260k data, 576k init)
> (more lines skipped)
> [    0.000000]  memory used by lock dependency info: 5855 kB
> [    0.000000]  per task-struct memory footprint: 1920 bytes
> [    0.000000] hpet clockevent registered
> [    0.000000] tsc: Fast TSC calibration using PIT
> [    0.000000] tsc: Detected 2527.012 MHz processor
> [    0.001004] Calibrating delay loop (skipped), value calculated using
> timer frequency.. 5054.02 BogoMIPS (lpj=2527012)
> [    0.001009] pid_max: default: 32768 minimum: 301
> [    0.001100] Security Framework initialized
>
> It probably simply be that your code is running before the clock is started
> by the kernel.
>



-- 
With regards,
Sandeep Kumar Anantapalli,
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