From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Fernandes Subject: Re: [PATCH v3 2/2] doc: Update documentation for page_idle virtual address indexing Date: Fri, 26 Jul 2019 16:26:47 -0400 Message-ID: <20190726202647.GA213712@google.com> References: <20190726152319.134152-1-joel@joelfernandes.org> <20190726152319.134152-2-joel@joelfernandes.org> <20190726201710.GA144547@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190726201710.GA144547@google.com> Sender: linux-kernel-owner@vger.kernel.org To: sspatil@google.com Cc: linux-kernel@vger.kernel.org, adobriyan@gmail.com, akpm@linux-foundation.org, bgregg@netflix.com, chansen3@cisco.com, dancol@google.com, fmayer@google.com, joaodias@google.com, corbet@lwn.net, keescook@chromium.org, kernel-team@android.com, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, rppt@linux.ibm.com, minchan@kernel.org, namhyung@google.com, guro@fb.com, sfr@canb.auug.org.au, surenb@google.com, tkjos@google.com, vdavydov.dev@gmail.com, vbabka@suse.cz, wvw@google.com, sspatil+mutt@google.com List-Id: linux-api@vger.kernel.org On Fri, Jul 26, 2019 at 01:17:10PM -0700, sspatil@google.com wrote: > Thanks Joel, just a couple of nits for the doc inline below. Other than that, > > Reviewed-by: Sandeep Patil 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) > > --- > > .../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 ` 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//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