On Fri, Jul 26, 2019 at 01:17:10PM -0700, sspatil@xxxxxxxxxx wrote: > Thanks Joel, just a couple of nits for the doc inline below. Other than that, > > Reviewed-by: Sandeep Patil <sspatil@xxxxxxxxxx> Thanks! > I'll plan on making changes to Android to use this instead of the pagemap + > page_idle. I think it will also be considerably faster. Cool, glad to know. > On Fri, Jul 26, 2019 at 11:23:19AM -0400, Joel Fernandes (Google) wrote: > > This patch updates the documentation with the new page_idle tracking > > feature which uses virtual address indexing. > > > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > > --- > > .../admin-guide/mm/idle_page_tracking.rst | 43 ++++++++++++++++--- > > 1 file changed, 36 insertions(+), 7 deletions(-) > > > > diff --git a/Documentation/admin-guide/mm/idle_page_tracking.rst b/Documentation/admin-guide/mm/idle_page_tracking.rst > > index df9394fb39c2..1eeac78c94a7 100644 > > --- a/Documentation/admin-guide/mm/idle_page_tracking.rst > > +++ b/Documentation/admin-guide/mm/idle_page_tracking.rst > > @@ -19,10 +19,14 @@ It is enabled by CONFIG_IDLE_PAGE_TRACKING=y. > > > > User API > > ======== > > +There are 2 ways to access the idle page tracking API. One uses physical > > +address indexing, another uses a simpler virtual address indexing scheme. > > > > -The idle page tracking API is located at ``/sys/kernel/mm/page_idle``. > > -Currently, it consists of the only read-write file, > > -``/sys/kernel/mm/page_idle/bitmap``. > > +Physical address indexing > > +------------------------- > > +The idle page tracking API for physical address indexing using page frame > > +numbers (PFN) is located at ``/sys/kernel/mm/page_idle``. Currently, it > > +consists of the only read-write file, ``/sys/kernel/mm/page_idle/bitmap``. > > > > The file implements a bitmap where each bit corresponds to a memory page. The > > bitmap is represented by an array of 8-byte integers, and the page at PFN #i is > > @@ -74,6 +78,31 @@ See :ref:`Documentation/admin-guide/mm/pagemap.rst <pagemap>` for more > > information about ``/proc/pid/pagemap``, ``/proc/kpageflags``, and > > ``/proc/kpagecgroup``. > > > > +Virtual address indexing > > +------------------------ > > +The idle page tracking API for virtual address indexing using virtual page > > +frame numbers (VFN) is located at ``/proc/<pid>/page_idle``. It is a bitmap > > +that follows the same semantics as ``/sys/kernel/mm/page_idle/bitmap`` > > +except that it uses virtual instead of physical frame numbers. > > + > > +This idle page tracking API does not need deal with PFN so it does not require > > s/need// > > > +prior lookups of ``pagemap`` in order to find if page is idle or not. This is > > s/in order to find if page is idle or not// Fixed both, thank you! Will send out update soon. thanks, - Joel
