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virtio: Add memory statistics reporting to the balloon driver (V4)

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Changes since V3:
 - Do not do endian conversions as they will be done in the host
 - Report stats that reference a quantity of memory in bytes
 - Minor coding style updates

Changes since V2:
 - Increase stat field size to 64 bits
 - Report all sizes in kb (not pages)
 - Drop anon_pages stat and fix endianness conversion

Changes since V1:
 - Use a virtqueue instead of the device config space

When using ballooning to manage overcommitted memory on a host, a system for
guests to communicate their memory usage to the host can provide information
that will minimize the impact of ballooning on the guests.  The current method
employs a daemon running in each guest that communicates memory statistics to a
host daemon at a specified time interval.  The host daemon aggregates this
information and inflates and/or deflates balloons according to the level of
host memory pressure.  This approach is effective but overly complex since a
daemon must be installed inside each guest and coordinated to communicate with
the host.  A simpler approach is to collect memory statistics in the virtio
balloon driver and communicate them directly to the hypervisor.

This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.

Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor fixes)
This commit is contained in:
Adam Litke
2009-11-30 10:14:15 -06:00
committed by Rusty Russell
parent 1f08b833dd
commit 9564e138b1
2 changed files with 101 additions and 8 deletions
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15
include/linux/virtio_balloon.h
View File

@ -7,6 +7,7 @@
/* The feature bitmap for virtio balloon */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@ -18,4 +19,18 @@ struct virtio_balloon_config
/* Number of pages we've actually got in balloon. */
__le32 actual;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
#define VIRTIO_BALLOON_S_SWAP_OUT 1 /* Amount of memory swapped out */
#define VIRTIO_BALLOON_S_MAJFLT 2 /* Number of major faults */
#define VIRTIO_BALLOON_S_MINFLT 3 /* Number of minor faults */
#define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */
#define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
#define VIRTIO_BALLOON_S_NR 6
struct virtio_balloon_stat {
u16 tag;
u64 val;
} __attribute__((packed));
#endif /* _LINUX_VIRTIO_BALLOON_H */