On Thu, Jul 03, 2014 at 12:53:01PM -0700, Andi Kleen wrote: > Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> writes: > > > In dcache.h, DNAME_INLINE_LEN is carefully chosen so that sizeof(struct > > dentry) is a (specific) multiple of 64 bytes. Obviously this breaks when > > certain debug options are chosen (DEBUG_LOCK_ALLOC and DEBUG_SPINLOCK), > > but also, AFAICT, on architectures with CONFIG_GENERIC_LOCKBREAK. > > > > I'm not sure it matters, but if it does, I'd suggest putting a > > BUILD_BUG_ON somewhere, protected by suitable #ifdefs, so that the code > > documents the assumptions that went into the particular choice of > > DNAME_INLINE_LEN (this would also help catch changes to some of the > > structures embedded in struct dentry which would violate those > > assumptions). > > The right fix would be to pad it correctly for these other variants > too. IF you've turned on debugging options, then you've already lost more performance that careful packing of the dentry slab cache gains you. There's no point in carefully tuning DNAME_INLINE_LEN for debug options - it's just code that will break and annoy people as debug implementations change. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
