On 11/02/18 23:16, Matthew Wilcox wrote: > On Sun, Feb 11, 2018 at 05:19:17AM +0200, Igor Stoppa wrote: >> The struct page has a "mapping" field, which can be re-used, to store a >> pointer to the parent area. This will avoid more expensive searches. >> >> As example, the function find_vm_area is reimplemented, to take advantage >> of the newly introduced field. > > Umm. Is it more efficient? You're replacing an rb-tree search with a > page-table walk. You eliminate a spinlock, which is great, but is the > page-table walk more efficient? I suppose it'll depend on the depth of > the rb-tree, and (at least on x86), the page tables should already be > in cache.
I thought the tradeoff favorable. How to verify it? > Unrelated to this patch, I'm working on a patch to give us page_type, > and I think I'll allocate a bit to mark pages which are vmalloced. pmalloced too? -- igor
