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[Qemu-devel] [PULL 03/17] balloon: add a feature bit to let Guest OS def
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PULL 03/17] balloon: add a feature bit to let Guest OS deflate balloon on oom |
Date: |
Fri, 26 Jun 2015 15:45:48 +0200 |
From: "Denis V. Lunev" <address@hidden>
Excessive virtio_balloon inflation can cause invocation of OOM-killer,
when Linux is under severe memory pressure. Various mechanisms are
responsible for correct virtio_balloon memory management. Nevertheless it
is often the case that these control tools does not have enough time to
react on fast changing memory load. As a result OS runs out of memory and
invokes OOM-killer. The balancing of memory by use of the virtio balloon
should not cause the termination of processes while there are pages in the
balloon. Now there is no way for virtio balloon driver to free memory at
the last moment before some process get killed by OOM-killer.
This does not provide a security breach as balloon itself is running
inside Guest OS and is working in the cooperation with the host. Thus
some improvements from Guest side should be considered as normal.
To solve the problem, introduce a virtio_balloon callback which is
expected to be called from the oom notifier call chain in out_of_memory()
function. If virtio balloon could release some memory, it will make the
system return and retry the allocation that forced the out of memory
killer to run.
This behavior should be enabled if and only if appropriate feature bit
is set on the device. It is off by default.
This functionality was recently merged into vanilla Linux.
commit 5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5
Author: Raushaniya Maksudova <address@hidden>
Date: Mon Nov 10 09:36:29 2014 +1030
This patch adds respective control bits into QEMU. It introduces
deflate-on-oom option for balloon device which does the trick.
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Raushaniya Maksudova <address@hidden>
CC: Anthony Liguori <address@hidden>
CC: Michael S. Tsirkin <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
Acked-by: James Bottomley <address@hidden>
Reviewed-by: Christian Borntraeger <address@hidden>
---
include/hw/virtio/virtio-balloon.h | 1 +
hw/virtio/virtio-balloon.c | 4 ++++
2 files changed, 5 insertions(+)
diff --git a/include/hw/virtio/virtio-balloon.h
b/include/hw/virtio/virtio-balloon.h
index 346a9fd..09c2ce4 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -42,6 +42,7 @@ typedef struct VirtIOBalloon {
QEMUTimer *stats_timer;
int64_t stats_last_update;
int64_t stats_poll_interval;
+ uint32_t host_features;
} VirtIOBalloon;
#endif
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 78bc14f..2990f8d 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -312,6 +312,8 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f)
{
+ VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
+ f |= dev->host_features;
virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
return f;
}
@@ -423,6 +425,8 @@ static void virtio_balloon_instance_init(Object *obj)
}
static Property virtio_balloon_properties[] = {
+ DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features,
+ VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
DEFINE_PROP_END_OF_LIST(),
};
--
MST
- [Qemu-devel] [PULL 00/17] virtio, pci fixes, enhancements, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 01/17] virito-pci: fix OVERRUN problem, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 02/17] qdev: fix OVERFLOW_BEFORE_WIDEN, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 03/17] balloon: add a feature bit to let Guest OS deflate balloon on oom,
Michael S. Tsirkin <=
- [Qemu-devel] [PULL 04/17] vhost: correctly pass error to caller in vhost_dev_enable_notifiers(), Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 05/17] MAINTAINERS: add ACPI entry, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 06/17] pc: cleanup and convert TMP ACPI device description to AML API, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 07/17] add pci-bridge-seat, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 08/17] migration: introduce VMSTATE_BUFFER_UNSAFE_INFO_TEST(), Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 09/17] hw/pci-bridge: expose _test parameter in SHPC_VMSTATE(), Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 10/17] hw/pci-bridge: add macro for "chassis_nr" property, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 11/17] hw/pci-bridge: add macro for "msi" property, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 12/17] hw/pci: introduce shpc_present() helper function, Michael S. Tsirkin, 2015/06/26
- [Qemu-devel] [PULL 13/17] hw/pci-bridge: introduce "shpc" property, Michael S. Tsirkin, 2015/06/26