linux-kernel - Re: [PATCH] drm: drm_err: Remove unnecessary __func_

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Date:	Mon, 13 Oct 2014 08:54:52 -0700
From:	Joe Perches <joe@...ches.com>
To:	David Herrmann <dh.herrmann@...il.com>
Cc:	Dave Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm: drm_err: Remove unnecessary __func__ argument

On Mon, 2014-10-13 at 17:46 +0200, David Herrmann wrote:
> Hi
> 
> On Sun, Oct 12, 2014 at 7:08 AM, Joe Perches <joe@...ches.com> wrote:
> > Removing the unnecessary drm_err __func__ argument by using
> > the equivalent %pf and __builtin_return_address(0) makes the
> > code smaller for every use of the DRM_ERROR macro.
> >
> > For instance: (allmodconfig)
> >
> > $ size drivers/gpu/drm/i915/i915.o*
> >    text    data     bss     dec     hex filename
> >  922447  193257  296736 1412440  158d58 drivers/gpu/drm/i915/i915.o.new
> >  928111  193257  296736 1418104  15a378 drivers/gpu/drm/i915/i915.o.old
> 
> You might want to mention that this requires a binary-search through
> kallsyms on each call.

All these calls are infrequently taken error paths
and the cost of the printk itself is _far_ higher
than a binary search for the symbol.

> I guess that's the reason you didn't use it for
> drm_ut_debug_printk()? I'm fine with doing this on drm_err(). Looks
> good.

No, the reason I didn't do it there is that those calls
should really be consolidated and be able to use dynamic_debug.
It'd be a separate patch.

cheers, Joe

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