On Mon, 2018-08-27 at 18:04 +1000, Nicholas Piggin wrote: > > Yes.. I see that. tlb_remove_check_page_size_change() really is a rather > > ugly thing, it can cause loads of TLB flushes. Do you really _have_ to > > do that? The way ARM and x86 work is that using INVLPG in a 4K stride is > > still correct for huge pages, inefficient maybe, but so is flushing > > every other page because 'sparse' transparant-huge-pages. > > It could do that. It requires a tlbie that matches the page size, > so it means 3 sizes. I think possibly even that would be better > than current code, but we could do better if we had a few specific > fields in there. More tlbies ? With the cost of the broadasts on the fabric ? I don't think so.. or I'm not understanding your point... Sadly our architecture requires a precise match between the page size specified in the tlbie instruction and the entry in the TLB or it won't be flushed. Ben.
