On Fri, Feb 28, 2020 at 11:38:16AM +0800, Huang, Ying wrote: > MADV_FREE is a lazy free mechanism in Linux. According to the manpage > of mavise(2), the semantics of MADV_FREE is, > > The application no longer requires the pages in the range specified > by addr and len. The kernel can thus free these pages, but the > freeing could be delayed until memory pressure occurs. ... > > Originally, the pages freed lazily by MADV_FREE will only be freed > really by page reclaiming when there is memory pressure or when > unmapping the address range. In addition to that, there's another > opportunity to free these pages really, when we try to migrate them. > > The main value to do that is to avoid to create the new memory > pressure immediately if possible. Instead, even if the pages are > required again, they will be allocated gradually on demand. That is, > the memory will be allocated lazily when necessary. This follows the > common philosophy in the Linux kernel, allocate resources lazily on > demand. Do you have an example program which does this (and so benefits)? If so, can you quantify the benefit at all?
