On Mon, Nov 20, 2017 at 07:56:28PM +0900, Tetsuo Handa wrote: > Christoph Hellwig wrote: > > On Mon, Nov 20, 2017 at 10:42:37AM +0100, Michal Hocko wrote: > > > The patch has been dropped because allnoconfig failed to compile back > > > then http://lkml.kernel.org/r/CAP=VYLr0rPWi1aeuk4w1On9CYRNmnEWwJgGtaX=wEvGaBURtrg@xxxxxxxxxxxxxx > > > I have problem to find the follow up discussion though. The main > > > argument was that SRC is not generally available and so the core > > > kernel should rely on it. > > > > Paul, > > > > isthere any good reason to not use SRCU in the core kernel and > > instead try to reimplement it using atomic counters? > > CONFIG_SRCU was added in order to save system size. There are users who run Linux on very > small systems ( https://www.elinux.org/images/5/52/Status-of-embedded-Linux-2017-09-JJ62.pdf ). > > Also, atomic counters are not mandatory for shrinker case; e.g. > http://lkml.kernel.org/r/201711161956.EBF57883.QFFMOLOVSOHJFt@xxxxxxxxxxxxxxxxxxx . CONFIG_SRCU was indeed added in order to shrink single-CPU systems. But many architectures are now requiring SRCU for one reason or another, in more and more situations. So I recently implemented a UP-only Tiny SRCU, which is quite a bit smaller than its scalable counterpart, Tree SRCU: text data bss dec hex filename 983 64 0 1047 417 /tmp/c/kernel/rcu/srcutiny.o text data bss dec hex filename 6844 193 0 7037 1b7d /tmp/b/kernel/rcu/srcutree.o So perhaps it is time to unconditionally enable SRCU? Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
