On Tue, 2014-02-11 at 02:56 +0000, Al Viro wrote: > > So the question is, is it reasonable to have the ref smaller than > > 32-bit... > > Every time you open a file, you bump dentry refcount. Something like > libc or ld.so will be opened on just about every execve(), so I'd say > that 16 bits is far too low. If nothing else, 32 bits might be too > low on 64bit boxen...
So back to square 1 ... we can't implement together lockref, ticket locks, and our lock confer mechanism within 64-bit. I see two options at this stage. Both require a custom implementation of lockref for powerpc, so some ifdef's such that we can replace the generic implementation completely. - We can use a small ref, and when it's too big, overflow into a larger one, falling back to the "old style" lock + ref (an overflow bit or a compare with ffff) - We can have lockref "build" it's own lock out of the ticketpair and ref, keeping the owner in a separate word. The owner doesn't strictly need to be atomic. Both are gross though :( Anybody has a better idea ? Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
