On Mon 16 Apr 2018 04:05:21 PM CEST, Max Reitz wrote: >> Refcount entries are used to reference host clusters, and host >> clusters are always(*) allocated sequentially, so caching refcount >> blocks doesn't do much. You're always loading the same refcount block >> until it's full, then you move on to the next one. As I mentioned in >> a previous e-mail, having a very large refcount cache would even be >> detrimental because it would make cache hits slower (noticeable under >> tmpfs). > > Ah, right. I'm not sure whether I want to ask you whether you have > tested internal snapshots. I suppose it can be detrimental for them > because when taking or deleting a snapshot you need to update the > refcounts of a whole bunch of clusters that might be spread randomly > across the image. But I suspect that it would be rather > time-consuming to produce an image with such a configuration; and I > suppose if people want to make heavy use of internal snapshots they > can adapt the cache size themselves?