linux-kernel - Re: [PATCH RFC 0/3] Static calls

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Date:   Mon, 12 Nov 2018 16:56:35 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jason Baron <jbaron@...mai.com>, Jiri Kosina <jkosina@...e.cz>,
        David Laight <David.Laight@...LAB.COM>,
        Borislav Petkov <bp@...en8.de>, Juergen Gross <jgross@...e.com>
Subject: Re: [PATCH RFC 0/3] Static calls

On Mon, Nov 12, 2018 at 12:03:34PM -0500, Steven Rostedt wrote:
> On Sun, 11 Nov 2018 23:30:55 -0600
> Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> 
> > > How much of that slowdown is reversed?  
> > 
> > In theory, it should reverse all of the slowdown, and actually may even
> > speed it up a little.  Steve is working on measuring that now.
> 
> When I'm able to get it to work! Hopefully that last patch snippet you
> posted will help. If not, I'm assuming you'll be in Vancouver this
> week, and we could sit down and work it out.

Sure, I'm already in Vancouver.  Just grab me if you see me, or ping me
on IRC/email.  Or feel free to send me your patches if it's still giving
you trouble.

> That said, I don't expect a 100% improvement. Because the retpoline
> causes slow down in other areas than just tracing, which is not being
> fixed by this. I'm expecting a substantial improvement (which I see
> good improvement with the unoptimized static calls), and hoping for
> much more with the optimized one (when I get it working). But not 100%,
> as stated above.

Ah, ok.  Makes sense.

-- 
Josh