linux-kernel - Re: [PATCH 1/3] tracing: Merge irqflags + preempt counter.

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Message-ID: <20210125145529.6f20ec4e@gandalf.local.home>
Date:   Mon, 25 Jan 2021 14:55:29 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/3] tracing: Merge irqflags + preempt counter.

On Mon, 25 Jan 2021 20:52:28 +0100
Sebastian Andrzej Siewior <bigeasy@...utronix.de> wrote:

> On 2021-01-25 14:03:23 [-0500], Steven Rostedt wrote:
> > 
> > I was thinking about the inlining for two reasons. One was to consolidate
> > the logic in the header file, as they are small functions. And two, inlined
> > functions tend to be faster than non-inlined functions. Thus, I wasn't
> > looking at this from a size point of view, but since this is called by all
> > events, including function tracer, being efficient is a requirement.  
> 
> In the ftrace_syscall_enter() example I made, flags were not evaluated
> three times but only once. This should do more in terms of performance
> compare to simply inline it.

Oh, I know. It's one of the things I like about your series. But that
doesn't make it less of a reason to inline it ;-)

> 
> > > I can post the irqflags-merge and the inlinining as two seprate patches
> > > and you can then decide if you merge the two patches or drop the
> > > inlining.  
> > 
> > Feel free to send it as separate patches. I'd like to have the inlining.  
> 
> Just sent as an extra patch. In case you have a benchmark, I'm curious
> ;)
> 

Yep, looking at it now. Thanks!

-- Steve