On Wed, Jun 17, 2020 at 5:53 PM Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote: > > The kernel uses internal mounts created by kern_mount() and populated > with files with no lookup path by alloc_file_pseudo() for a variety of > reasons. An relevant example is anonymous pipes because every vfs_write > also checks if atime needs to be updated even though it is unnecessary. > Most of the relevant users for alloc_file_pseudo() either have no statfs > helper or use simple_statfs which does not return st_atime. The closest st_atime is returned by simple_getattr() > proxy measure is the proc fd representations of such inodes which do not > appear to change once they are created. This patch sets the S_NOATIME > on inode->i_flags for inodes created by new_inode_pseudo() so that atime > will not be updated. > new_inode() calls new_inode_pseudo() ... You need to factor out a new helper. Either you can provide callers analysis of all new_inode_pseudo() users or use a new helper to set S_NOATIME and call it from the relevant users (pipe, socket). How about S_NOCMTIME while you are at it? Doesn't file_update_time() show in profiling? Is there a valid use case for updating c/mtime of anonymous socket/pipe? Thanks, Amir.
