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[209.85.220.65]) by mx.google.com with SMTPS id g71sor64043014pje.16.2019.07.26.13.26.50 for (Google Transport Security); Fri, 26 Jul 2019 13:26:50 -0700 (PDT) Received-SPF: pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=OSSRdZkS; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=IE5eJowpyCcGnZE2pKcSc9umsrWgUqBG7zCK+NjEKK4=; b=OSSRdZkSZXg6M+b9FWF3a1q+TiPSBp244enRgIGdVZjUu/SD8K8PRf3KqpHJ6cYWhk n3RevHiDEbDWb3xewyJUfr/5dEQwWqMIwnEbk87NSvS9caP8hIT7G5fh4UfLVUxKM38z JNXY9crOfbFD7ctsGRXt2fiHSx0KEPhd66l6Y= X-Google-Smtp-Source: APXvYqwxNJxyl8AMaL5MbjN3DCH0CGh1VKzKZSR7IsnpnOEC6DeGs6F8TvHMF+yBHu4tkJDhVOJeUA== X-Received: by 2002:a17:90a:4f0e:: with SMTP id p14mr96514100pjh.40.1564172810042; Fri, 26 Jul 2019 13:26:50 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id f19sm77269906pfk.180.2019.07.26.13.26.48 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 26 Jul 2019 13:26:49 -0700 (PDT) Date: Fri, 26 Jul 2019 16:26:47 -0400 From: Joel Fernandes 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 Subject: Re: [PATCH v3 2/2] doc: Update documentation for page_idle virtual address indexing 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 Content-Disposition: inline In-Reply-To: <20190726201710.GA144547@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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