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qemu-kvm: Change balloon page size to 1MB

PATCH New Prasad Joshi 2 participants 3 messages Feb 20, 2012 – Feb 21, 2012

Subsystems (3)
KVM virtio core virtio balloon
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Prasad Joshi

author
#0 lore raw

PATCH 1/1 qemu-kvm: Change balloon page size to 1MB

Signed-off-by Prasad Joshi <[email protected]>
---
 hw/virtio-balloon.c |    2 +-
 hw/virtio-balloon.h |    6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)
hw/virtio-balloon.c +1 -1
index ce9d2c9..765dd97 100644
@@ -48,7 +48,7 @@ static void balloon_page(void *addr, int deflate)
 {
 #if defined(__linux__)
     if (!kvm_enabled() || kvm_has_sync_mmu())
-        qemu_madvise(addr, TARGET_PAGE_SIZE,
+        qemu_madvise(addr, BALLOON_PAGE_SIZE,
                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
 #endif
 }
hw/virtio-balloon.h +5 -1
index 73300dd..0da82bf 100644
@@ -28,7 +28,11 @@
 #define VIRTIO_BALLOON_F_STATS_VQ 1       /* Memory stats virtqueue */
 
 /* Size of a PFN in the balloon interface. */
-#define VIRTIO_BALLOON_PFN_SHIFT 12
+#define VIRTIO_BALLOON_PFN_SHIFT 20
+
+/* Size of the balloon page */
+#define BALLOON_PAGE_SIZE (1UL << VIRTIO_BALLOON_PFN_SHIFT)
+
 
 struct virtio_balloon_config
 {
Signature · 1 line
1.7.5.4
author
#1 lore raw

PATCH 1/1 virtio-balloon: Change balloon page size to 1MB

Signed-off-by Prasad Joshi <[email protected]>
---
 drivers/virtio/virtio_balloon.c |   18 +++++++++---------
 include/linux/virtio_balloon.h  |    4 +++-
 2 files changed, 12 insertions(+), 10 deletions(-)
drivers/virtio/virtio_balloon.c +9 -9
index 95aeedf..e352448 100644
@@ -64,9 +64,8 @@ static u32 page_to_balloon_pfn(struct page *page)
 {
 	unsigned long pfn = page_to_pfn(page);
 
-	BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
 	/* Convert pfn from Linux page size to balloon page size. */
-	return pfn >> (PAGE_SHIFT - VIRTIO_BALLOON_PFN_SHIFT);
+	return pfn >> VIRTIO_BALLOON_PAGE_ORDER;
 }
 
 static void balloon_ack(struct virtqueue *vq)

@@ -102,8 +101,9 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
 	num = min(num, ARRAY_SIZE(vb->pfns));
 
 	for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
-		struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
-					__GFP_NOMEMALLOC | __GFP_NOWARN);
+		struct page *page = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
+				__GFP_NOMEMALLOC | __GFP_NOWARN,
+				VIRTIO_BALLOON_PAGE_ORDER);
 		if (!page) {
 			if (printk_ratelimit())
 				dev_printk(KERN_INFO, &vb->vdev->dev,

@@ -114,7 +114,7 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
 			break;
 		}
 		vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
-		totalram_pages--;
+		totalram_pages -= VIRTIO_BALLOON_PAGES;
 		vb->num_pages++;
 		list_add(&page->lru, &vb->pages);
 	}

@@ -131,8 +131,8 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
 	unsigned int i;
 
 	for (i = 0; i < num; i++) {
-		__free_page(pfn_to_page(pfns[i]));
-		totalram_pages++;
+		__free_pages(pfn_to_page(pfns[i]), VIRTIO_BALLOON_PAGE_ORDER);
+		totalram_pages += VIRTIO_BALLOON_PAGES;
 	}
 }
 

@@ -146,7 +146,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
 	for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
 		page = list_first_entry(&vb->pages, struct page, lru);
 		list_del(&page->lru);
-		vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
+		vb->pfns[vb->num_pfns] = page_to_pfn(page);
 		vb->num_pages--;
 	}
 

@@ -400,7 +400,7 @@ static int virtballoon_restore(struct virtio_device *vdev)
 	/* We don't have these pages in the balloon anymore! */
 	list_for_each_entry_safe(page, page2, &vb->pages, lru) {
 		list_del(&page->lru);
-		totalram_pages++;
+		totalram_pages += VIRTIO_BALLOON_PAGES;
 	}
 	return init_vqs(vdev->priv);
 }
include/linux/virtio_balloon.h +3 -1
index 652dc8b..86840fe 100644
@@ -33,7 +33,9 @@
 #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue */
 
 /* Size of a PFN in the balloon interface. */
-#define VIRTIO_BALLOON_PFN_SHIFT 12
+#define VIRTIO_BALLOON_PFN_SHIFT  20
+#define VIRTIO_BALLOON_PAGE_ORDER (VIRTIO_BALLOON_PFN_SHIFT - PAGE_SHIFT)
+#define VIRTIO_BALLOON_PAGES      (1U << VIRTIO_BALLOON_PAGE_ORDER)
 
 struct virtio_balloon_config
 {
Signature · 1 line
1.7.4.1
#2 lore raw

Re: [PATCH] virtio-balloon: Change balloon page size to 1MB

Quoted 1 line · Prasad Joshi
Signed-off-by Prasad Joshi<[email protected]>

This breaks compatibility with existing guests and more importantly, doesn't make any sense. There's no commit message explaining why 1MB is a better number than 4K, 2MB which I could at least understand as an alternative to 4K.

Regards,

Anthony Liguori

Quoted 85 lines
---
  drivers/virtio/virtio_balloon.c |   18 +++++++++---------
  include/linux/virtio_balloon.h  |    4 +++-
  2 files changed, 12 insertions(+), 10 deletions(-)
drivers/virtio/virtio_balloon.c +9 -9
index 95aeedf..e352448 100644
@@ -64,9 +64,8 @@ static u32 page_to_balloon_pfn(struct page *page)
  {
  	unsigned long pfn = page_to_pfn(page);
 
-	BUILD_BUG_ON(PAGE_SHIFT<  VIRTIO_BALLOON_PFN_SHIFT);
  	/* Convert pfn from Linux page size to balloon page size. */
-	return pfn>>  (PAGE_SHIFT - VIRTIO_BALLOON_PFN_SHIFT);
+	return pfn>>  VIRTIO_BALLOON_PAGE_ORDER;
  }
 
  static void balloon_ack(struct virtqueue *vq)

@@ -102,8 +101,9 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
  	num = min(num, ARRAY_SIZE(vb->pfns));
 
  	for (vb->num_pfns = 0; vb->num_pfns<  num; vb->num_pfns++) {
-		struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
-					__GFP_NOMEMALLOC | __GFP_NOWARN);
+		struct page *page = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
+				__GFP_NOMEMALLOC | __GFP_NOWARN,
+				VIRTIO_BALLOON_PAGE_ORDER);
  		if (!page) {
  			if (printk_ratelimit())
  				dev_printk(KERN_INFO,&vb->vdev->dev,

@@ -114,7 +114,7 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
  			break;
  		}
  		vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
-		totalram_pages--;
+		totalram_pages -= VIRTIO_BALLOON_PAGES;
  		vb->num_pages++;
  		list_add(&page->lru,&vb->pages);
  	}

@@ -131,8 +131,8 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
  	unsigned int i;
 
  	for (i = 0; i<  num; i++) {
-		__free_page(pfn_to_page(pfns[i]));
-		totalram_pages++;
+		__free_pages(pfn_to_page(pfns[i]), VIRTIO_BALLOON_PAGE_ORDER);
+		totalram_pages += VIRTIO_BALLOON_PAGES;
  	}
  }
 

@@ -146,7 +146,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
  	for (vb->num_pfns = 0; vb->num_pfns<  num; vb->num_pfns++) {
  		page = list_first_entry(&vb->pages, struct page, lru);
  		list_del(&page->lru);
-		vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
+		vb->pfns[vb->num_pfns] = page_to_pfn(page);
  		vb->num_pages--;
  	}
 

@@ -400,7 +400,7 @@ static int virtballoon_restore(struct virtio_device *vdev)
  	/* We don't have these pages in the balloon anymore! */
  	list_for_each_entry_safe(page, page2,&vb->pages, lru) {
  		list_del(&page->lru);
-		totalram_pages++;
+		totalram_pages += VIRTIO_BALLOON_PAGES;
  	}
  	return init_vqs(vdev->priv);
  }
include/linux/virtio_balloon.h +3 -1
index 652dc8b..86840fe 100644
@@ -33,7 +33,9 @@
  #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue */
 
  /* Size of a PFN in the balloon interface. */
-#define VIRTIO_BALLOON_PFN_SHIFT 12
+#define VIRTIO_BALLOON_PFN_SHIFT  20
+#define VIRTIO_BALLOON_PAGE_ORDER (VIRTIO_BALLOON_PFN_SHIFT - PAGE_SHIFT)
+#define VIRTIO_BALLOON_PAGES      (1U<<  VIRTIO_BALLOON_PAGE_ORDER)
 
  struct virtio_balloon_config
  {