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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. Signed-off-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/*
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* Virtio Support
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*
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* Copyright IBM, Corp. 2007-2008
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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* Rusty Russell <rusty@rustcorp.com.au>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef _QEMU_VIRTIO_BALLOON_H
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#define _QEMU_VIRTIO_BALLOON_H
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#include "virtio.h"
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#include "pci.h"
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/* from Linux's linux/virtio_balloon.h */
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/* The ID for virtio_balloon */
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#define VIRTIO_ID_BALLOON 5
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/* The feature bitmap for virtio balloon */
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#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
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#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory stats virtqueue */
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/* Size of a PFN in the balloon interface. */
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#define VIRTIO_BALLOON_PFN_SHIFT 12
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struct virtio_balloon_config
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{
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/* Number of pages host wants Guest to give up. */
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uint32_t num_pages;
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/* Number of pages we've actually got in balloon. */
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uint32_t actual;
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};
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/* Memory Statistics */
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#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
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#define VIRTIO_BALLOON_S_SWAP_OUT 1 /* Amount of memory swapped out */
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#define VIRTIO_BALLOON_S_MAJFLT 2 /* Number of major faults */
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#define VIRTIO_BALLOON_S_MINFLT 3 /* Number of minor faults */
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#define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */
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#define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
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#define VIRTIO_BALLOON_S_NR 6
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typedef struct VirtIOBalloonStat {
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uint16_t tag;
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uint64_t val;
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} __attribute__((packed)) VirtIOBalloonStat;
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#endif
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