Re: [RFC PATCH v2] tinification: Introduce CONFIG_SRCU to make SRCU optional

[Pranith Kumar <bobby.prani@gmail.com>]

On 12/04/2014 01:27 AM, Paul E. McKenney wrote:
> For the moment, I applied this to -rcu against v3.18-rc6 to get some 0day
> testing on it.
> 
> There are conflicts against the tip of my tree, but will worry about
> that later.  I don't have a ready answer on whether or not this needs
> to be split up -- in the worst case, we would add the SRCU Kconfig
> parameter, add all the selects, then once they all hit mainline add the
> Makefile change.
> 
> We will need stats on how much memory was saved, and a "size kernel/rcu/srcu.o"
> after a UP/tiny build should do it.  Could you please add this to the
> commit log?
> 

So if we do not select CONFIG_SRCU, srcu.o will not be compiled at all. So we should save about

   text	   data	    bss	    dec	    hex	filename
   2007	      0	      0	   2007	    7d7	kernel/rcu/srcu.o

as in size of arch/powerpc/boot/zImage changes from

   text	   data	    bss	    dec	    hex	filename
 831552	  64180	  23944	 919676	  e087c	arch/powerpc/boot/zImage : before
 829504	  64180	  23952	 917636	  e0084	arch/powerpc/boot/zImage : after

so about ~2000 bytes I guess. 

--
Pranith