From: Dave Chinner <david@fromorbit.com>
To: "Theodore Y. Ts'o" <tytso@mit.edu>, Joe Perches <joe@perches.com>,
Eric Sandeen <sandeen@sandeen.net>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Christoph Hellwig <hch@lst.de>,
linux-xfs@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] xfs: Remove noinline from #define STATIC
Date: Tue, 13 Nov 2018 14:09:26 +1100 [thread overview]
Message-ID: <20181113030926.GQ19305@dastard> (raw)
In-Reply-To: <20181113015410.GB30750@thunk.org>
On Mon, Nov 12, 2018 at 08:54:10PM -0500, Theodore Y. Ts'o wrote:
> On Tue, Nov 13, 2018 at 12:18:05PM +1100, Dave Chinner wrote:
> > I'm not interested in making code fast if distro support engineers
> > can't debug problems on user systems easily. Optimising for
> > performance over debuggability is a horrible trade off for us to
> > make because it means users and distros end up much more reliant on
> > single points of expertise for debugging problems. And that means
> > the majority of the load of problem triage falls directly on very
> > limited resources - the core XFS development team. A little bit of
> > thought about how to make code easier to triage and debug goes a
> > long, long way....
>
> So at least in my experience, if the kernels are compiled with
> CONFIG_DEBUG_INFO and/or CONFIG_DEBUG_INFO_REDUCED,
> scripts/decode_stracktrace.sh seems to do a very nice job with inlined
That doesn't help with kernel profiling and other such things that
are based on callgraphs...
> functions. Now, ext4 generally only has about 3 or 4 nested inlines,
> and so I don't know how it works with 20 or 30 nested inlined
> functions, so perhaps this is not applicable for XFS.
>
> But it perhaps toolchain technology has advanced since the Irix days
> such that it's no longer as necessary to force the non-inlining of
> functions for easing debugging?
Not that I've noticed.
Indeed, modern toolchains are moving the opposite direction - have
you ever tried to debug a binary with gdb that was compiled with LTO
enabled? Or maybe even just tried to profile it with perf?
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2018-11-13 13:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-11 1:21 [PATCH] xfs: Remove noinline from #define STATIC Joe Perches
2018-11-12 20:12 ` Eric Sandeen
2018-11-12 21:05 ` Joe Perches
2018-11-12 21:45 ` Dave Chinner
2018-11-12 22:30 ` Joe Perches
2018-11-13 1:18 ` Dave Chinner
2018-11-13 1:54 ` Theodore Y. Ts'o
2018-11-13 3:09 ` Dave Chinner [this message]
2018-11-13 4:23 ` Joe Perches
2018-11-13 5:26 ` Dave Chinner
2018-11-13 5:31 ` Joe Perches
2018-11-13 5:44 ` Darrick J. Wong
2018-11-15 10:12 ` Christoph Hellwig
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