From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
x86@kernel.org, Jinchao Wang <wangjinchao600@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ian Rogers <irogers@google.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v4 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint
Date: Thu, 18 Sep 2025 07:42:48 +0900 [thread overview]
Message-ID: <20250918074248.09cc039bd81ad7ffe2b4b09f@kernel.org> (raw)
In-Reply-To: <f8d432e0-e220-4857-8d4e-427332ce837a@infradead.org>
On Wed, 17 Sep 2025 10:13:36 -0700
Randy Dunlap <rdunlap@infradead.org> wrote:
>
>
> On 9/17/25 7:38 AM, Masami Hiramatsu (Google) wrote:
> >> + # 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) <mhiramat@kernel.org>
next prev parent reply other threads:[~2025-09-17 22:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-14 14:09 [PATCH v4 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
2025-09-14 14:09 ` [PATCH v4 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint Masami Hiramatsu (Google)
2025-09-15 0:14 ` Randy Dunlap
2025-09-17 14:38 ` Masami Hiramatsu
2025-09-17 17:13 ` Randy Dunlap
2025-09-17 22:42 ` Masami Hiramatsu [this message]
2025-09-14 14:09 ` [PATCH v4 2/8] x86/hw_breakpoint: Unify breakpoint install/uninstall Masami Hiramatsu (Google)
2025-09-14 14:10 ` [PATCH v4 3/8] x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint Masami Hiramatsu (Google)
2025-09-14 14:10 ` [PATCH v4 4/8] HWBP: Add modify_wide_hw_breakpoint_local() API Masami Hiramatsu (Google)
2025-09-14 14:10 ` [PATCH v4 5/8] tracing: wprobe: Add wprobe event trigger Masami Hiramatsu (Google)
2025-09-15 0:25 ` Randy Dunlap
2025-09-17 14:14 ` Masami Hiramatsu
2025-09-14 14:10 ` [PATCH v4 6/8] selftests: tracing: Add a basic testcase for wprobe Masami Hiramatsu (Google)
2025-09-14 14:10 ` [PATCH v4 7/8] selftests: tracing: Add syntax " Masami Hiramatsu (Google)
2025-09-14 14:11 ` [PATCH v4 8/8] selftests: ftrace: Add wprobe trigger testcase Masami Hiramatsu (Google)
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