On Fri, Apr 17, 2020 at 01:18:37PM +0800, Huang, Ying wrote: > Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > > > On Fri, 17 Apr 2020 11:01:22 +0800 "Huang\, Ying" <ying.huang@xxxxxxxxx> wrote: > > > >> Andrea Righi <andrea.righi@xxxxxxxxxxxxx> writes: > >> > >> > In unuse_pte_range() we blindly swap-in pages without checking if the > >> > swap entry is already present in the swap cache. > >> > > >> > By doing this, the hit/miss ratio used by the swap readahead heuristic > >> > is not properly updated and this leads to non-optimal performance during > >> > swapoff. > >> > >> It's more important to describe why we need this patch in the patch > >> description. So, please add some information about your use case. And > >> please focus on the technical part instead of the business part. > > > > Confused. I thought the changelog was quite good. If "business part" > > means "end user effect of the patch" then that's a very important > > thing. > > Previously, Andrea has described their use case in the cloud environment > to hiberate the guest and swapoff after resuming. So swapoff > performance is important for them. I think that should be included. > For the business part, I mean something like "Ubuntu used in AWS EC2", I > think that isn't important for the patch description. I just sent a v4 of this patch adding "conclusion" section in the description to better explain the purpose of this patch. Let me know if you have any comment on that. Thanks, -Andrea
