From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6BAEB2D46B7; Wed, 17 Sep 2025 22:42:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758148975; cv=none; b=I5yEx6xi+FU6Cav99318J+qbF/03BpJgYpdb6EwXwCmAVlDiukkSt9WaEBGv98mYNccO+jGVnngYBbPeFt5DTHdLc7uZCZ/3SIC7vFyUf7LKFYgmW6v7etHA4Xl7gVvfsyLgChQWIBRZrutoJ5kehq4u/Yyr99b0YFVxk6A6JtM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758148975; c=relaxed/simple; bh=1fYjV9I/mts9hAv/Oa99SQdbOQ5xxivRisDGmyAWMSM=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=tdQH70f33XDxN3ZL/eG1Be+XGIE9NNFXR0jNEmlNgAxyV9CSh9rCOClDDnZGODtq4dR47I7VOi6Zug6A2hNRVG4nqRTxl0lj6xTsJ8pTxAvXi4/9XcpQ2F+1/5YAEuq3CZBuRr2eNaQN2THy8Jml5JlNJd22faBL9uN748vX9ic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NLKzgBEF; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NLKzgBEF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA4AFC4CEE7; Wed, 17 Sep 2025 22:42:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758148975; bh=1fYjV9I/mts9hAv/Oa99SQdbOQ5xxivRisDGmyAWMSM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=NLKzgBEFZ4Zyy9Vu1S7pJNy1W+OOx1we/8MNJZgHs6vBIFDyDpOBQABwtI+sS+NZt JUzwocZAwa0giR4M3UmUQl5QebDUywpZNjbPrlCAa+G25DYnbqE7BWksR17SbBhdYO 8lVwzxofNTv3Sjuo8tfh0Vvg0F619jva3aw1GZDMYVyq/J96VRXQtzhJhfitKZ3TUh V8XNJGkDqD6JTHTzIWVceN4U03pUaFKIKmuvumkvctHeXe9SGootBsdYrbh01HboQH XSB2KOOwq/l+umVioi+qMSK3drlwHEvRE9zQPASM9vO0/fhPZIOjcxKhg3JXe3Vi30 cLP1XXeAtlmoQ== Date: Thu, 18 Sep 2025 07:42:48 +0900 From: Masami Hiramatsu (Google) To: Randy Dunlap Cc: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org, Jinchao Wang , Mathieu Desnoyers , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , 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 Message-Id: <20250918074248.09cc039bd81ad7ffe2b4b09f@kernel.org> In-Reply-To: References: <175785897434.234168.6798590787777427098.stgit@devnote2> <175785898586.234168.14883193853242691280.stgit@devnote2> <014136d2-8599-4a1f-ab8e-c5be4f522e5a@infradead.org> <20250917233818.71678d0164a6fc2d11fa6e38@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 17 Sep 2025 10:13:36 -0700 Randy Dunlap wrote: > > > On 9/17/25 7:38 AM, Masami Hiramatsu (Google) wrote: > >> + # TASK-PID CPU# ||||| TIMESTAMP FUNCTION > >> + # | | | ||||| | | > >> + -0 [000] d.Z1. 717.026259: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130) > >> + -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)