linux-kernel - Re: [PATCH 3/3] x86/ftrace: Use text

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Message-Id: <20191003145230.fe8314d8575c2f88b16322e8@kernel.org>
Date:   Thu, 3 Oct 2019 14:52:30 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Daniel Bristot de Oliveira <bristot@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Nadav Amit <nadav.amit@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Song Liu <songliubraving@...com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 3/3] x86/ftrace: Use text_poke()

On Wed, 2 Oct 2019 18:35:26 +0200
Daniel Bristot de Oliveira <bristot@...hat.com> 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 you have any performance numbers of the previous code and applying this?

Thank you,


-- 
Masami Hiramatsu <mhiramat@...nel.org>