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 Please, see the measurement details to my answer to Stephen. > Btw. I totaly agree with Steven. This is a very poor changelog. It is > trivial to see what the patch does but it is far from clear why it is > doing that and why we cannot go other ways. We possibly can go another way, and there is comment to [2/10] about this. Percpu rwsem may be used instead, the only thing, it is worse, is it will make shrink_slab() wait unregistering shrinkers, while srcu-based implementation does not require this. This may be not a big problem. But, if SRCU is real problem for embedded people, I really don't want they hate me in the future because of this, so please CC someone if you know :) Kirill
