From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Nadav Amit <nadav.amit@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Song Liu <songliubraving@fb.com>,
Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 3/3] x86/ftrace: Use text_poke()
Date: Mon, 7 Oct 2019 10:08:47 +0200 [thread overview]
Message-ID: <20191007080847.GB2311@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <7b4196a4-b6e1-7e55-c3e1-a02d97c262c7@redhat.com>
On Fri, Oct 04, 2019 at 10:10:47AM +0200, Daniel Bristot de Oliveira wrote:
> 1) the enabling/disabling ftrace path
> 2) the int3 path - if a thread/irq is running a kernel function
> 3) the IPI - that affects all CPUs, even those that are not "hitting" trace
> code, e.g., user-space.
>
> The first one is for sure a cold-path. The second one is a hot-path: any task
> running kernel functions will hit it. But IMHO, the hottest one is the IPIs,
> because it will run on all CPUs, e.g., even isolated CPUs that are running in
> user-space.
Well, we can fix that, just like RCU. In fact, I suspect RCU has all the
bits required to cure this.
For NOHZ_FULL CPUs you can forgo the IPI and delay it until the next kernel
entry, just like RCU.
next prev parent reply other threads:[~2019-10-07 8:09 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 18:06 [PATCH 0/3] Rewrite x86/ftrace to use text_poke() Peter Zijlstra
2019-08-27 18:06 ` [PATCH 1/3] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-10-03 5:00 ` Masami Hiramatsu
2019-10-03 8:27 ` Peter Zijlstra
2019-10-03 11:01 ` Peter Zijlstra
2019-10-03 12:32 ` Peter Zijlstra
2019-10-04 13:45 ` Masami Hiramatsu
2019-10-07 8:05 ` Peter Zijlstra
2019-10-09 13:07 ` x86/kprobes bug? (was: [PATCH 1/3] x86/alternatives: Teach text_poke_bp() to emulate instructions) Peter Zijlstra
2019-10-09 13:26 ` Peter Zijlstra
2019-10-09 13:28 ` Peter Zijlstra
2019-10-09 14:26 ` Mathieu Desnoyers
2019-10-17 19:59 ` Peter Zijlstra
2019-10-03 13:05 ` [PATCH 1/3] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-08-27 18:06 ` [PATCH 2/3] x86/alternatives,jump_label: Provide better text_poke() batching interface Peter Zijlstra
2019-10-02 16:34 ` Daniel Bristot de Oliveira
2019-10-03 5:50 ` Masami Hiramatsu
2019-08-27 18:06 ` [PATCH 3/3] x86/ftrace: Use text_poke() Peter Zijlstra
2019-10-02 16:35 ` Daniel Bristot de Oliveira
2019-10-02 18:21 ` Peter Zijlstra
2019-10-03 22:10 ` Steven Rostedt
2019-10-04 8:10 ` Daniel Bristot de Oliveira
2019-10-04 13:40 ` Steven Rostedt
2019-10-04 14:44 ` Daniel Bristot de Oliveira
2019-10-04 15:13 ` Steven Rostedt
2019-10-07 8:08 ` Peter Zijlstra [this message]
2019-10-11 7:01 ` Peter Zijlstra
2019-10-11 7:37 ` Daniel Bristot de Oliveira
2019-10-11 10:57 ` Peter Zijlstra
2019-10-11 13:11 ` Steven Rostedt
2019-10-04 11:22 ` Peter Zijlstra
2019-10-04 13:42 ` Steven Rostedt
2019-10-22 0:36 ` Alexei Starovoitov
2019-10-22 0:43 ` Steven Rostedt
2019-10-22 3:10 ` Alexei Starovoitov
2019-10-22 3:16 ` Steven Rostedt
2019-10-22 3:19 ` Steven Rostedt
2019-10-22 4:05 ` Alexei Starovoitov
2019-10-22 11:19 ` Steven Rostedt
2019-10-22 13:44 ` Steven Rostedt
2019-10-22 17:50 ` Alexei Starovoitov
2019-10-22 18:10 ` Steven Rostedt
2019-10-22 20:46 ` Alexei Starovoitov
2019-10-22 21:04 ` Steven Rostedt
2019-10-22 21:58 ` Alexei Starovoitov
2019-10-22 22:17 ` Steven Rostedt
2019-10-23 2:02 ` Steven Rostedt
2019-10-22 22:45 ` Andy Lutomirski
2019-10-22 23:21 ` Steven Rostedt
2019-10-22 23:49 ` Alexei Starovoitov
2019-10-23 4:20 ` Andy Lutomirski
2019-10-23 9:02 ` Peter Zijlstra
2019-10-23 16:23 ` Steven Rostedt
2019-10-23 17:42 ` Steven Rostedt
2019-10-23 19:34 ` Alexei Starovoitov
2019-10-23 20:08 ` Steven Rostedt
2019-10-23 22:36 ` Alexei Starovoitov
2019-10-22 3:55 ` Alexei Starovoitov
2019-10-03 5:52 ` Masami Hiramatsu
2019-08-28 7:22 ` [PATCH 0/3] Rewrite x86/ftrace to use text_poke() Song Liu
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