On Sat, Dec 16, 2017 at 01:21:52AM +0900, Tetsuo Handa wrote: > My understanding is that virtio-balloon wants to handle sparsely spreaded > unsigned long values (which is PATCH 4/7) and wants to find all chunks of > consecutive "1" bits efficiently. Therefore, I guess that holding the values > in ascending order at store time is faster than sorting the values at read > time. Are you asking why is a bitmap used here, as opposed to a tree? It's not just store versus read. There's also the issue that memory can get highly fragmented, if it is, the number of 1s is potentially very high. A bitmap can use as little as 1 bit per value, it is hard to beat in this respect. -- MST
