From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: 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>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 3/3] x86/ftrace: Use text_poke()
Date: Wed, 2 Oct 2019 20:21:06 +0200 [thread overview]
Message-ID: <20191002182106.GC4643@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <aaffb32f-6ca9-f9e3-9b1a-627125c563ed@redhat.com>
On Wed, Oct 02, 2019 at 06:35:26PM +0200, Daniel Bristot de Oliveira wrote:
> ftrace was already batching the updates, for instance, causing 3 IPIs to enable
> all functions. The text_poke() batching also works. But because of the limited
> buffer [ see the reply to the patch 2/3 ], it is flushing the buffer during the
> operation, causing more IPIs than the previous code. Using the 5.4-rc1 in a VM,
> when enabling the function tracer, I see 250+ intermediate text_poke_finish()
> because of a full buffer...
>
> Would this be the case of trying to use a dynamically allocated buffer?
>
> Thoughts?
Is it a problem? I tried growing the buffer (IIRC I made it 10 times
bigger) and didn't see any performance improvements because of it.
next prev parent reply other threads:[~2019-10-02 18:21 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 [this message]
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
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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