From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 ADA222905; Wed, 17 Sep 2025 17:13:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758129228; cv=none; b=s0XUyNpPmmQBVgsmHVbsJgyXuX7qjmkvCnNf1mjJ71xrSe1GMBZCw/twD626I2tZS6hBfcQqpknqViwFPNDJNxB8Tm7Kqxvu7wKq7vEcsSBRF3ajejSaLdav+IOBsBBy4qThX6o1F3n+sJGASD558Od89cPp1sOzbhzmszEJLD0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758129228; c=relaxed/simple; bh=7utd2mNCGqv0fGRGHJlqKBPLh/85qlOzgzSj3DRpfGA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=lpB3UVBIRSfPBkNVI7SGuWywn3QjNrhN1oWvxuwMrCO4VBXl2Rm79lv1bNivzEZnpYnGJQ7z/qctJRCLw6mFK92I0wbbu06CZfyp9/nDREbPti5mhCS1+Jwi2TvBQEnpoZ8zSnHEw5KydvIdGMFm9iymZo7mS1wUAXk5fwQfMSQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=s/8W4GJW; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="s/8W4GJW" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Sender:Reply-To:Content-ID:Content-Description; bh=PWqxr35AzD9frV25voEqKDmiFYHwMk5p7VNBLNHixIU=; b=s/8W4GJWaIDo+n9p8W+SHHXkVl Fn6tiZ9I3k0bTLcNzUfK2eARfPMmb3YnFiGUjHNwBeDyPvfwpIH4T7eFh12E9epNABNHaniRiVGNZ faoJUG5fbaybuKgNChi4GfZRf9FNSfEwwI4OInG6x0/zDh56WpgrvMSYgAiecckuX56B6c299uQcI /N+oz9owL+iL4I7Bx/RnEvgduW/hyBfNrmY/I1eH40ahXsDyC/rL3HOSCXwXwA8Ty9QbAv6Qd2qlM IRp6eEtvkgeV+zfJ6mcNzn6eErXrAs4dyiDy/EfTp2b0nRC5TL2ASK1uXTsiqWCSlGcMSA06FGCTi NBmAeUvw==; Received: from [50.53.25.54] (helo=[192.168.254.17]) by bombadil.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uyvis-0000000DSn0-3zIx; Wed, 17 Sep 2025 17:13:38 +0000 Message-ID: Date: Wed, 17 Sep 2025 10:13:36 -0700 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint To: "Masami Hiramatsu (Google)" 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 References: <175785897434.234168.6798590787777427098.stgit@devnote2> <175785898586.234168.14883193853242691280.stgit@devnote2> <014136d2-8599-4a1f-ab8e-c5be4f522e5a@infradead.org> <20250917233818.71678d0164a6fc2d11fa6e38@kernel.org> Content-Language: en-US From: Randy Dunlap In-Reply-To: <20250917233818.71678d0164a6fc2d11fa6e38@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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? thanks. -- ~Randy