On Fri, May 31, 2019 at 10:50:44AM +0200, Michal Hocko wrote: > On Fri 31-05-19 15:43:10, Minchan Kim wrote: > > When a process expects no accesses to a certain memory range > > for a long time, it could hint kernel that the pages can be > > reclaimed instantly but data should be preserved for future use. > > This could reduce workingset eviction so it ends up increasing > > performance. > > > > This patch introduces the new MADV_PAGEOUT hint to madvise(2) > > syscall. MADV_PAGEOUT can be used by a process to mark a memory > > range as not expected to be used for a long time so that kernel > > reclaims the memory instantly. The hint can help kernel in deciding > > which pages to evict proactively. > > Again, are there any restictions on what kind of memory can be paged out? > Private/Shared, anonymous/file backed. Any restrictions on mapping type. > Etc. Please make sure all that is in the changelog. It's same with MADV_COLD. Yes, I will include all detail in the description. > > What are the failure modes? E.g. what if the swap is full, does the call > fails or it silently ignores the error? In such case, just ignore the swapout. It returns -EINVAL only if the vma is one of (VM_LOCKED|VM_HUGETLB|VM_PFNMAP) at this moment. > > Thanks! > -- > Michal Hocko > SUSE Labs
