Re: [Qemu-devel] [PATCH v7 kernel 5/5] This patch contains two parts:

[Wei Wang]

On 03/06/2017 09:23 PM, David Hildenbrand wrote:Am 03.03.2017 um 06:40 
schrieb Wei Wang:

From: Liang Li 

Sorry, I just saw the message due to an email issue.


I'd prefer to split this into two parts then and to create proper subjects.

Agree, will do.



If I remember correctly, the general concept was accepted by most reviewers.



Yes, that's also what I was told.

Best,
Wei

Re: [Qemu-devel] [PATCH v7 kernel 5/5] This patch contains two parts:

[David Hildenbrand]

Am 03.03.2017 um 06:40 schrieb Wei Wang:
> From: Liang Li 

I'd prefer to split this into two parts then and to create proper subjects.

If I remember correctly, the general concept was accepted by most reviewers.

> 
> One is to add a new API to mm go get the unused page information.
> The virtio balloon driver will use this new API added to get the
> unused page info and send it to hypervisor(QEMU) to speed up live
> migration. During sending the bitmap, some the pages may be modified
> and are used by the guest, this inaccuracy can be corrected by the
> dirty page logging mechanism.
> 
> One is to add support the request for vm's unused page information,
> QEMU can make use of unused page information and the dirty page
> logging mechanism to skip the transportation of some of these unused
> pages, this is very helpful to reduce the network traffic and speed
> up the live migration process.

-- 
Thanks,

David

[Qemu-devel] [PATCH v7 kernel 5/5] This patch contains two parts:

[Wei Wang]

From: Liang Li 

One is to add a new API to mm go get the unused page information.
The virtio balloon driver will use this new API added to get the
unused page info and send it to hypervisor(QEMU) to speed up live
migration. During sending the bitmap, some the pages may be modified
and are used by the guest, this inaccuracy can be corrected by the
dirty page logging mechanism.

One is to add support the request for vm's unused page information,
QEMU can make use of unused page information and the dirty page
logging mechanism to skip the transportation of some of these unused
pages, this is very helpful to reduce the network traffic and speed
up the live migration process.

Signed-off-by: Liang Li 
Signed-off-by: Wei Wang 
Cc: Andrew Morton 
Cc: Mel Gorman 
Cc: Michael S. Tsirkin 
Cc: Paolo Bonzini 
Cc: Cornelia Huck 
Cc: Amit Shah 
Cc: Dave Hansen 
Cc: Andrea Arcangeli 
Cc: David Hildenbrand 
Cc: Liang Li 
Cc: Wei Wang 
---
 drivers/virtio/virtio_balloon.c | 137 ++--
 include/linux/mm.h  |   3 +
 mm/page_alloc.c | 120 +++
 3 files changed, 255 insertions(+), 5 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 4416370..9b6cf44f 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -66,7 +66,7 @@ struct balloon_page_chunk_ext {
 
 struct virtio_balloon {
struct virtio_device *vdev;
-   struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
+   struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *host_req_vq;
 
/* The balloon servicing is delegated to a freezable workqueue. */
struct work_struct update_balloon_stats_work;
@@ -95,6 +95,8 @@ struct virtio_balloon {
unsigned int nr_page_bmap;
/* Used to record the processed pfn range */
unsigned long min_pfn, max_pfn, start_pfn, end_pfn;
+   /* Request header */
+   struct virtio_balloon_req_hdr req_hdr;
/*
 * The pages we've told the Host we're not using are enqueued
 * at vb_dev_info->pages list.
@@ -549,6 +551,80 @@ static void stats_handle_request(struct virtio_balloon *vb)
virtqueue_kick(vq);
 }
 
+static void __send_unused_pages(struct virtio_balloon *vb,
+   unsigned long req_id, unsigned int pos, bool done)
+{
+   struct virtio_balloon_resp_hdr *hdr = >resp_hdr;
+   struct virtqueue *vq = vb->host_req_vq;
+
+   vb->resp_pos = pos;
+   hdr->cmd = BALLOON_GET_UNUSED_PAGES;
+   hdr->id = req_id;
+   if (!done)
+   hdr->flag = BALLOON_FLAG_CONT;
+   else
+   hdr->flag = BALLOON_FLAG_DONE;
+
+   if (pos > 0 || done)
+   send_resp_data(vb, vq, true);
+
+}
+
+static void send_unused_pages(struct virtio_balloon *vb,
+   unsigned long req_id)
+{
+   struct scatterlist sg_in;
+   unsigned int pos = 0;
+   struct virtqueue *vq = vb->host_req_vq;
+   int ret, order;
+   struct zone *zone = NULL;
+   bool part_fill = false;
+
+   mutex_lock(>balloon_lock);
+
+   for (order = MAX_ORDER - 1; order >= 0; order--) {
+   ret = mark_unused_pages(, order, vb->resp_data,
+vb->resp_buf_size / sizeof(__le64),
+, VIRTIO_BALLOON_CHUNK_SIZE_SHIFT, part_fill);
+   if (ret == -ENOSPC) {
+   if (pos == 0) {
+   void *new_resp_data;
+
+   new_resp_data = kmalloc(2 * vb->resp_buf_size,
+   GFP_KERNEL);
+   if (new_resp_data) {
+   kfree(vb->resp_data);
+   vb->resp_data = new_resp_data;
+   vb->resp_buf_size *= 2;
+   } else {
+   part_fill = true;
+   dev_warn(>vdev->dev,
+"%s: part fill order: %d\n",
+__func__, order);
+   }
+   } else {
+   __send_unused_pages(vb, req_id, pos, false);
+   pos = 0;
+   }
+
+   if (!part_fill) {
+   order++;
+   continue;
+   }
+   } else
+   zone = NULL;
+
+