Re: [PATCH RFC 01/10] rcu: Make CONFIG_SRCU unconditionally enabled

Josh Triplett
2018-08-08T16:18:14Z

On Wed, Aug 08, 2018 at 01:17:44PM +0300, Kirill Tkhai wrote:
> On 08.08.2018 10:20, Michal Hocko wrote:
> > On Tue 07-08-18 18:37:36, Kirill Tkhai wrote:
> >> This patch kills all CONFIG_SRCU defines and
> >> the code under !CONFIG_SRCU.
> >
> > The last time somebody tried to do this there was a pushback due to
> > kernel tinyfication. So this should really give some numbers about the
> > code size increase. Also why can't we make this depend on MMU. Is
> > anybody else than the reclaim asking for unconditional SRCU usage?
>
> I don't know one. The size numbers (sparc64) are:
>
> $ size image.srcu.disabled
> text data bss dec hex filename
> 5117546 8030506 1968104 15116156 e6a77c image.srcu.disabled
> $ size image.srcu.enabled
> text data bss dec hex filename
> 5126175 8064346 1968104 15158625 e74d61 image.srcu.enabled
> The difference is: 15158625-15116156 = 42469 ~41Kb

41k is a *substantial* size increase. However, can you compare
tinyconfig with and without this patch? That may have a smaller change.