On Wed, 17 Sep 2025 10:13:36 -0700
Randy Dunlap [off-list ref] wrote:

On 9/17/25 7:38 AM, Masami Hiramatsu (Google) wrote:

quoted

quoted

+  #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
+  #              | |         |   |||||     |         |
+           <idle>-0       [000] d.Z1.  717.026259: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
+           <idle>-0       [000] d.Z1.  717.026373: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
+
+You can see the code which writes to `jiffies` is `do_timer()`.

I'm having trouble getting from tick_do_update_jiffies64+0xbe/0x130,
which I expect is
	jiffies_64 += ticks;
in that function, over to do_timer(), which also updates jiffies_64,
but is not called by tick_do_update_jiffies64(). AFAICT, there are
no calls to do_timer() in the file (kernel/time/tick-sched.c).

Can you explain, please?

Let me try this again.

I understand the stack (call) trace/dump and your explanation, but
then your next comment says:

+You can see the code which writes to `jiffies` is `do_timer()`.

Does that need to be corrected?

Oops! sorry I missed that. Let me fix that.

Thank you for catching!

Thanks,

thanks.
-- 
~Randy

-- 
Masami Hiramatsu (Google) [off-list ref]