On 13/12/19 21:23, Peter Xu wrote: >> What is the benefit of using u16 for that? That means with 4K pages, you >> can share at most 256M of dirty memory each time? That seems low to me, >> especially since it's sufficient to touch one byte in a page to dirty it. >> >> Actually, this is not consistent with the definition in the code ;-) >> So I'll assume it's actually u32. > Yes it's u32 now. Actually I believe at least Paolo would prefer u16 > more. :) It has to be u16, because it overlaps the padding of the first entry. Paolo > I think even u16 would be mostly enough (if you see, the maximum > allowed value currently is 64K entries only, not a big one). Again, > the thing is that the userspace should be collecting the dirty bits, > so the ring shouldn't reach full easily. Even if it does, we should > probably let it stop for a while as explained above. It'll be > inefficient only if we set it to a too-small value, imho. >
