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How to enable timestamp with nanoseconds resolution in linux kernel. Currently it shows in miliseconds resolution as below.

Is there any config or macro that i need to enable??? ....

[    0.220000] omap_mux_init: Add partition: #1: core, flags: 4
[    0.220000] ti81xx_register_mcasp: platform not supported
[    0.230000] Debugfs: Only enabling/disabling deep sleep and wakeup timer is supported now
[    0.230000] bio: create slab <bio-0> at 0
[    0.230000] SCSI subsystem initialized
[    0.230000] usbcore: registered new interface driver usbfs
[    0.230000] usbcore: registered new interface driver hub
[    0.230000] usbcore: registered new device driver usb
[    0.230000] omap_i2c omap_i2c.1: bus 1 rev4.0 at 100 kHz
[    0.260000] omap_i2c omap_i2c.2: bus 2 rev4.0 at 100 kHz
[    0.280000] omap_i2c omap_i2c.3: bus 3 rev4.0 at 100 kHz
[    0.300000] omap_i2c omap_i2c.4: bus 4 rev4.0 at 100 kHz
[    0.300000] Switching to clocksource gp timer
[    0.310000] musb-hdrc: version 6.0, otg (peripheral+host), debug=0
[    0.310000] NET: Registered protocol family 2
[    0.310000] IP route cache hash table entries: 4096 (order: 2, 16384 bytes)
[    0.310000] TCP established hash table entries: 16384 (order: 5, 131072 bytes)
[    0.310000] TCP bind hash table entries: 16384 (order: 4, 65536 bytes)
[    0.310000] TCP: Hash tables configured (established 16384 bind 16384)
[    0.310000] TCP reno registered
[    0.310000] UDP hash table entries: 256 (order: 0, 4096 bytes)
[    0.310000] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[    0.310000] NET: Registered protocol family 1
[    0.310000] RPC: Registered udp transport module.
[    0.310000] RPC: Registered tcp transport module.
[    0.310000] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.310000] Trying to unpack rootfs image as initramfs...
[    0.310000] rootfs image is not initramfs (no cpio magic); looks like an initrd
[    0.330000] Freeing initrd memory: 3660K
[    0.330000] NetWinder Floating Point Emulator V0.97 (double precision)

....

Nirav Rabara
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1 Answers1

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From this Printk Times article in the troubleshooting section;

  • Resolution of timings is very bad.
    • Printk-time uses the routine sched_clock() in the kernel. On some platforms, sched_clock() only has a resolution of 1 jiffy (which may be 10 milliseconds or longer). This means that you will only see the time increment at this resolution, giving imprecise results for printk-times. To correct this problem, the best solution is to implement a good sched_clock() routine for your platform. Sched_clock() returns a 64-bit value which is nanoseconds since some event (usually either since machine power-on, or since time_init() was called.) Many embedded processors have a clock or timer on the System-On-Chip which can provide a good resolution clock source for sched_clock(). It is best if the clock can provide resolution better than 1 microsecond. Note that this only requires a clock running at 1 MHz to achieve this resolution.

It sounds like your platform is using jiffies at 1 ms resolution for sched_clock().

benf
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