linux-kernel - Re: [PATCH] xfs: allow disabling xfs tracepoints via Kconfig

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Message-ID: <4d66f2c2-bf5c-be47-9ef1-e581c5901823@rasmusvillemoes.dk>
Date:   Mon, 4 Feb 2019 23:12:57 +0100
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Dave Chinner <david@...morbit.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     "Darrick J. Wong" <darrick.wong@...cle.com>,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xfs: allow disabling xfs tracepoints via Kconfig

On 04/02/2019 22.53, Dave Chinner wrote:
> On Mon, Feb 04, 2019 at 10:20:35PM +0100, Rasmus Villemoes wrote:
>> linux/tracepoints.h allows individual subsystems to disable their
>> tracepoints. Add such a knob for xfs. Disabling XFS_TRACEPOINTS
>> reduces the resident size of xfs.ko by about a third, or ~350 KiB.
> 
> Ok, now we can't debug typical problems on live production systems
> if tracepoints are turned off on the user/distro kernels.  So under
> what circumstances would we ever want to turn off tracepoints on
> XFS?

I don't expect any mainstream distros to turn it off. But for embedded
systems that use a hand-tuned .config, being able to shave off 100s of K
of the kernel image is quite valuable. Tracing _is_ useful,
also/especially when doing embedded development, which is why "just turn
off CONFIG_TRACING" isn't really an option.

Would the knob be more acceptable if it was under CONFIG_EXPERT?

Rasmus