From: David Hildenbrand <david@redhat.com>
To: Alexander Duyck <alexander.duyck@gmail.com>,
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, 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: Re: [PATCH v16.1 6/9] virtio-balloon: Add support for providing free page reports to host
Date: Tue, 11 Feb 2020 12:03:57 +0100 [thread overview]
Message-ID: <b8cbf72d-55a7-4a58-6d08-b0ac5fa86e82@redhat.com> (raw)
In-Reply-To: <20200122174347.6142.92803.stgit@localhost.localdomain>
On 22.01.20 18:43, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
>
> Add support for the page reporting feature provided by virtio-balloon.
> Reporting differs from the regular balloon functionality in that is is
> much less durable than a standard memory balloon. Instead of creating a
> list of pages that cannot be accessed the pages are only inaccessible
> while they are being indicated to the virtio interface. Once the
> interface has acknowledged them they are placed back into their respective
> free lists and are once again accessible by the guest system.
>
> Unlike a standard balloon we don't inflate and deflate the pages. Instead
> we perform the reporting, and once the reporting is completed it is
> assumed that the page has been dropped from the guest and will be faulted
> back in the next time the page is accessed.
>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
> drivers/virtio/Kconfig | 1 +
> drivers/virtio/virtio_balloon.c | 64 +++++++++++++++++++++++++++++++++++
> include/uapi/linux/virtio_balloon.h | 1 +
> 3 files changed, 66 insertions(+)
>
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 078615cf2afc..4b2dd8259ff5 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -58,6 +58,7 @@ config VIRTIO_BALLOON
> tristate "Virtio balloon driver"
> depends on VIRTIO
> select MEMORY_BALLOON
> + select PAGE_REPORTING
> ---help---
> This driver supports increasing and decreasing the amount
> of memory within a KVM guest.
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 40bb7693e3de..a07b9e18a292 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -19,6 +19,7 @@
> #include <linux/mount.h>
> #include <linux/magic.h>
> #include <linux/pseudo_fs.h>
> +#include <linux/page_reporting.h>
>
> /*
> * Balloon device works in 4K page units. So each page is pointed to by
> @@ -47,6 +48,7 @@ enum virtio_balloon_vq {
> VIRTIO_BALLOON_VQ_DEFLATE,
> VIRTIO_BALLOON_VQ_STATS,
> VIRTIO_BALLOON_VQ_FREE_PAGE,
> + VIRTIO_BALLOON_VQ_REPORTING,
> VIRTIO_BALLOON_VQ_MAX
> };
>
> @@ -114,6 +116,10 @@ struct virtio_balloon {
>
> /* To register a shrinker to shrink memory upon memory pressure */
> struct shrinker shrinker;
> +
> + /* Free page reporting device */
> + struct virtqueue *reporting_vq;
> + struct page_reporting_dev_info pr_dev_info;
> };
>
> static struct virtio_device_id id_table[] = {
> @@ -153,6 +159,33 @@ static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
>
> }
>
> +int virtballoon_free_page_report(struct page_reporting_dev_info *pr_dev_info,
> + struct scatterlist *sg, unsigned int nents)
> +{
> + struct virtio_balloon *vb =
> + container_of(pr_dev_info, struct virtio_balloon, pr_dev_info);
> + struct virtqueue *vq = vb->reporting_vq;
> + unsigned int unused, err;
> +
> + /* We should always be able to add these buffers to an empty queue. */
> + err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT | __GFP_NOWARN);
> +
> + /*
> + * In the extremely unlikely case that something has occurred and we
> + * are able to trigger an error we will simply display a warning
> + * and exit without actually processing the pages.
> + */
> + if (WARN_ON_ONCE(err))
> + return err;
> +
> + virtqueue_kick(vq);
> +
> + /* When host has read buffer, this completes via balloon_ack */
> + wait_event(vb->acked, virtqueue_get_buf(vq, &unused));
> +
> + return 0;
> +}
Did you see the discussion regarding unifying handling of
inflate/deflate/free_page_hinting_free_page_reporting, requested by
Michael? I think free page reporting is special and shall be left alone.
VIRTIO_BALLOON_F_REPORTING is nothing but a more advanced inflate, right
(sg, inflate based on size - not "virtio pages")? And you rely on
deflates not being required before reusing an inflated page.
I suggest the following:
/* New interface (+ 2 virtqueues) to inflate/deflate using a SG */
VIRTIO_BALLOON_F_SG
/*
* No need to deflate when reusing pages (once the inflate request was
* processed). Applies to all inflate queues.
*/
VIRTIO_BALLOON_F_OPTIONAL_DEFLATE
And two new virtqueues
VIRTIO_BALLOON_VQ_INFLATE_SG
VIRTIO_BALLOON_VQ_DEFLATE_SG
Your feature would depend on VIRTIO_BALLOON_F_SG &&
VIRTIO_BALLOON_F_OPTIONAL_DEFLATE. VIRTIO_BALLOON_F_OPTIONAL_DEFLATE
could be reused to avoid deflating on certain events (e.g., from
OOM/shrinker).
Thoughts?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-02-11 11:04 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-22 17:43 [PATCH v16.1 0/9] mm / virtio: Provide support for free page reporting Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 1/9] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 2/9] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 3/9] mm: Add function __putback_isolated_page Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 4/9] mm: Introduce Reported pages Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 5/9] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 6/9] virtio-balloon: Add support for providing free page reports to host Alexander Duyck
2020-02-11 11:03 ` David Hildenbrand [this message]
2020-02-11 11:47 ` Michael S. Tsirkin
2020-02-11 12:19 ` David Hildenbrand
2020-02-11 14:07 ` Michael S. Tsirkin
2020-02-11 14:31 ` David Hildenbrand
2020-02-11 14:48 ` Michael S. Tsirkin
2020-02-11 15:13 ` David Hildenbrand
2020-02-11 16:33 ` Alexander Duyck
2020-02-11 17:04 ` David Hildenbrand
2020-01-22 17:43 ` [PATCH v16.1 7/9] mm/page_reporting: Rotate reported pages to the tail of the list Alexander Duyck
2020-01-22 17:43 ` [PATCH v16.1 8/9] mm/page_reporting: Add budget limit on how many pages can be reported per pass Alexander Duyck
2020-01-22 17:44 ` [PATCH v16.1 9/9] mm/page_reporting: Add free page reporting documentation Alexander Duyck
2020-01-23 10:20 ` [PATCH v16.1 0/9] mm / virtio: Provide support for free page reporting Alexander Graf
2020-01-23 14:05 ` David Hildenbrand
2020-01-23 14:52 ` Alexander Graf
2020-01-24 13:25 ` David Hildenbrand
2020-01-24 16:20 ` David Hildenbrand
2020-01-23 16:26 ` Alexander Duyck
2020-01-23 16:54 ` Alexander Graf
2020-01-23 18:33 ` Alexander Duyck
2020-01-23 18:47 ` Graf (AWS), Alexander
2020-01-23 22:05 ` Alexander Duyck
2020-01-23 17:20 ` Dave Hansen
2020-01-23 19:23 ` Konrad Rzeszutek Wilk
2020-01-23 19:17 ` Johannes Weiner
2020-01-23 22:29 ` Alexander Duyck
2020-01-23 23:24 ` Dave Hansen
2020-01-24 13:23 ` Hillf Danton
2020-01-24 16:40 ` Alexander Graf
2020-01-25 2:01 ` Hillf Danton
2020-02-03 22:05 ` Alexander Duyck
2020-02-10 19:18 ` Should I repost? (was: Re: [PATCH v16.1 0/9] mm / virtio: Provide support for free page reporting) Alexander Duyck
2020-02-11 10:40 ` Mel Gorman
2020-02-11 22:57 ` Alexander Duyck
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