linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexander Duyck <alexander.duyck@gmail.com>
To: kvm@vger.kernel.org, mst@redhat.com,
	linux-kernel@vger.kernel.org, willy@infradead.org,
	mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org,
	mgorman@techsingularity.net, vbabka@suse.cz
Cc: yang.zhang.wz@gmail.com, nitesh@redhat.com,
	konrad.wilk@oracle.com, david@redhat.com, pagupta@redhat.com,
	riel@surriel.com, lcapitulino@redhat.com, dave.hansen@intel.com,
	wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com,
	dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com,
	osalvador@suse.de
Subject: [PATCH v15 7/7] mm: Add free page reporting documentation
Date: Thu, 05 Dec 2019 08:23:04 -0800	[thread overview]
Message-ID: <20191205162304.19548.33406.stgit@localhost.localdomain> (raw)
In-Reply-To: <20191205161928.19548.41654.stgit@localhost.localdomain>

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

Add documentation for free page reporting. Currently the only consumer is
virtio-balloon, however it is possible that other drivers might make use of
this so it is best to add a bit of documetation explaining at a high level
how to use the API.

Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 Documentation/vm/free_page_reporting.rst |   41 ++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 Documentation/vm/free_page_reporting.rst

diff --git a/Documentation/vm/free_page_reporting.rst b/Documentation/vm/free_page_reporting.rst
new file mode 100644
index 000000000000..33f54a450a4a
--- /dev/null
+++ b/Documentation/vm/free_page_reporting.rst
@@ -0,0 +1,41 @@
+.. _free_page_reporting:
+
+=====================
+Free Page Reporting
+=====================
+
+Free page reporting is an API by which a device can register to receive
+lists of pages that are currently unused by the system. This is useful in
+the case of virtualization where a guest is then able to use this data to
+notify the hypervisor that it is no longer using certain pages in memory.
+
+For the driver, typically a balloon driver, to use of this functionality
+it will allocate and initialize a page_reporting_dev_info structure. The
+field within the structure it will populate is the "report" function
+pointer used to process the scatterlist. It must also guarantee that it can
+handle at least PAGE_REPORTING_CAPACITY worth of scatterlist entries per
+call to the function. A call to page_reporting_register will register the
+page reporting interface with the reporting framework assuming no other
+page reporting devices are already registered.
+
+Once registered the page reporting API will begin reporting batches of
+pages to the driver. The API will start reporting pages 2 seconds after
+the interface is registered and will continue to do so 2 seconds after any
+page of a sufficiently high order is freed.
+
+Pages reported will be stored in the scatterlist passed to the reporting
+function with the final entry having the end bit set in entry nent - 1.
+While pages are being processed by the report function they will not be
+accessible to the allocator. Once the report function has been completed
+the pages will be returned to the free area from which they were obtained.
+
+Prior to removing a driver that is making use of free page reporting it
+is necessary to call page_reporting_unregister to have the
+page_reporting_dev_info structure that is currently in use by free page
+reporting removed. Doing this will prevent further reports from being
+issued via the interface. If another driver or the same driver is
+registered it is possible for it to resume where the previous driver had
+left off in terms of reporting free pages.
+
+Alexander Duyck, Dec 04, 2019
+


  parent reply	other threads:[~2019-12-05 16:23 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-05 16:22 [PATCH v15 0/7] mm / virtio: Provide support for free page reporting Alexander Duyck
2019-12-05 16:22 ` [PATCH v15 1/7] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-12-05 16:22 ` [PATCH v15 2/7] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-12-05 16:22 ` [PATCH v15 3/7] mm: Add function __putback_isolated_page Alexander Duyck
2019-12-16 11:36   ` David Hildenbrand
2019-12-16 16:22     ` Alexander Duyck
2019-12-17 10:58       ` David Hildenbrand
2019-12-17 16:26         ` Alexander Duyck
2019-12-17 17:24           ` David Hildenbrand
2019-12-17 18:24             ` Alexander Duyck
2019-12-17 18:46               ` David Hildenbrand
2019-12-17 21:50                 ` Alexander Duyck
2019-12-05 16:22 ` [PATCH v15 4/7] mm: Introduce Reported pages Alexander Duyck
2019-12-16 10:17   ` Nitesh Narayan Lal
2019-12-16 16:28     ` Alexander Duyck
2019-12-17  8:55       ` Nitesh Narayan Lal
2019-12-17 16:31         ` Alexander Duyck
2019-12-18  7:31           ` Mel Gorman
2019-12-16 11:44   ` Nitesh Narayan Lal
2019-12-16 16:10     ` Alexander Duyck
2019-12-05 16:22 ` [PATCH v15 5/7] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2019-12-13  7:03   ` Michael S. Tsirkin
2019-12-05 16:22 ` [PATCH v15 6/7] virtio-balloon: Add support for providing free page reports to host Alexander Duyck
2019-12-13  7:08   ` Michael S. Tsirkin
2019-12-13 16:35     ` Alexander Duyck
2019-12-15  9:29       ` Michael S. Tsirkin
2019-12-13 10:15   ` David Hildenbrand
2019-12-13 16:37     ` Alexander Duyck
2019-12-05 16:23 ` Alexander Duyck [this message]
2019-12-05 16:24 ` [PATCH v15 QEMU 1/3] virtio-ballon: Implement support for page poison tracking feature Alexander Duyck
2019-12-05 16:24 ` [PATCH v15 QEMU 2/3] virtio-balloon: Add bit to notify guest of unused page reporting Alexander Duyck
2019-12-05 16:24 ` [PATCH v15 QEMU 3/3] virtio-balloon: Provide a interface for " Alexander Duyck
2019-12-05 16:26 ` [PATCH v15 QEMU 4/3 RFC] memory: Add support for MADV_FREE as mechanism to lazy discard pages Alexander Duyck
2019-12-12 23:47 ` [PATCH v15 0/7] mm / virtio: Provide support for free page reporting Alexander Duyck
2019-12-13 10:00 ` David Hildenbrand
2019-12-13 11:08   ` Mel Gorman
2019-12-13 16:59     ` Alexander Duyck
2019-12-13 16:46   ` Alexander Duyck
2019-12-16 12:21     ` David Hildenbrand

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191205162304.19548.33406.stgit@localhost.localdomain \
    --to=alexander.duyck@gmail.com \
    --cc=aarcange@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.h.duyck@linux.intel.com \
    --cc=dan.j.williams@intel.com \
    --cc=dave.hansen@intel.com \
    --cc=david@redhat.com \
    --cc=konrad.wilk@oracle.com \
    --cc=kvm@vger.kernel.org \
    --cc=lcapitulino@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@techsingularity.net \
    --cc=mhocko@kernel.org \
    --cc=mst@redhat.com \
    --cc=nitesh@redhat.com \
    --cc=osalvador@suse.de \
    --cc=pagupta@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=riel@surriel.com \
    --cc=vbabka@suse.cz \
    --cc=wei.w.wang@intel.com \
    --cc=willy@infradead.org \
    --cc=yang.zhang.wz@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).