On Fri, Mar 08, 2024 at 04:48:11AM +0000, Matthew Wilcox wrote: > On Thu, Mar 07, 2024 at 10:13:22PM -0500, Kent Overstreet wrote: > > This steals it to make __ksize() faster; it's now a single dependent > > load, instead of two. This is going to be important for tracking the > > amount of memory stranded by RCU, which we want to be able to do if > > we're going to be freeing all pagecache folios (and perhaps all folios) > > via RCU. > > Do you have any measurements? I don't necessarily object, it's just > that I would have thought we were already bringing slab->slab_cache > into cache as part of the freeing operation. for kfree() yes, but for kfree_rcu() no - that'll happen significantly later. I don't have measurements that it /matters/, but since we have the u32 there now this seems like a good use for it.
