On Fri 09-08-19 07:57:44, Yang Shi wrote: > When doing partial unmap to THP, the pages in the affected range would > be considered to be reclaimable when memory pressure comes in. And, > such pages would be put on deferred split queue and get minus from the > memory statistics (i.e. /proc/meminfo). > > For example, when doing THP split test, /proc/meminfo would show: > > Before put on lazy free list: > MemTotal: 45288336 kB > MemFree: 43281376 kB > MemAvailable: 43254048 kB > ... > Active(anon): 1096296 kB > Inactive(anon): 8372 kB > ... > AnonPages: 1096264 kB > ... > AnonHugePages: 1056768 kB > > After put on lazy free list: > MemTotal: 45288336 kB > MemFree: 43282612 kB > MemAvailable: 43255284 kB > ... > Active(anon): 1094228 kB > Inactive(anon): 8372 kB > ... > AnonPages: 49668 kB > ... > AnonHugePages: 10240 kB > > The THPs confusingly look disappeared although they are still on LRU if > you are not familair the tricks done by kernel. Is this a fallout of the recent deferred freeing work? > Accounted the lazy free pages to NR_LAZYFREE, and show them in meminfo > and other places. With the change the /proc/meminfo would look like: > Before put on lazy free list: The name is really confusing because I have thought of MADV_FREE immediately. > +LazyFreePages: Cleanly freeable pages under memory pressure (i.e. deferred > + split THP). What does that mean actually? I have hard time imagine what cleanly freeable pages mean. -- Michal Hocko SUSE Labs
