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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.

  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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