On Sun, Jan 04, 2015 at 08:35:52PM +1100, Michael Ellerman wrote:

On Tue, 2014-12-30 at 13:54 -0500, Pranith Kumar wrote:

quoted

On Tue, Dec 30, 2014 at 1:50 PM, Peter Zijlstra [off-list ref] wrote:

quoted

On Tue, Dec 30, 2014 at 12:46:22AM -0500, Pranith Kumar wrote:

quoted

Isolate the SRCU functions and data structures within CONFIG_SRCU so that there
is a compile time failure if srcu is used when not enabled. This was decided to
be better than waiting until link time for a failure to occur.

Why?

This is part of the kernel tinification efforts. The first patch was
posted here: https://lkml.org/lkml/2014/12/4/848. This patch enables a
compile time failure instead of a link time failure.

The punch line was:

  "so the savings are about ~2000 bytes."

Which is utterly not worth the effort IMO. There have got to be more attractive
targets for tinification than this.

There probably are.  But if the tinification effort is to come anywhere
near reaching its goals, it is going to need 2000-byte savings, especially
on the small systems that are this effort's main target.

That said, Peter's suggestion of falling back to the link-time diagnostic
does simplify things a bit, and might be a good approach.

							Thanx, Paul