search for: free_pages_bitmap

...+122,23 @@ void qmp_balloon(int64_t target, Error **errp) trace_balloon_event(balloon_opaque, target); balloon_event_fn(balloon_opaque, target); } + +bool balloon_free_pages_support(void) +{ + return balloon_free_pages_fn ? true : false; +} + +int balloon_get_free_pages(unsigned long *free_pages_bitmap, + unsigned long *free_pages_count) +{ + if (!balloon_free_pages_fn) { + return -1; + } + + if (!free_pages_bitmap || !free_pages_count) { + return -1; + } + + return balloon_free_pages_fn(balloon_opaque, + free_...

...**errp) > trace_balloon_event(balloon_opaque, target); > balloon_event_fn(balloon_opaque, target); > } > + > +bool balloon_free_pages_support(void) > +{ > + return balloon_free_pages_fn ? true : false; > +} > + > +int balloon_get_free_pages(unsigned long *free_pages_bitmap, > + unsigned long *free_pages_count) > +{ > + if (!balloon_free_pages_fn) { > + return -1; > + } > + > + if (!free_pages_bitmap || !free_pages_count) { > + return -1; > + } > + > + return balloon_free_pages_fn(...

The current QEMU live migration implementation mark the all the guest's RAM pages as dirtied in the ram bulk stage, all these pages will be processed and that takes quit a lot of CPU cycles. >From guest's point of view, it doesn't care about the content in free pages. We can make use of this fact and skip processing the free pages in the ram bulk stage, it can save a lot CPU cycles

The current QEMU live migration implementation mark the all the guest's RAM pages as dirtied in the ram bulk stage, all these pages will be processed and that takes quit a lot of CPU cycles. >From guest's point of view, it doesn't care about the content in free pages. We can make use of this fact and skip processing the free pages in the ram bulk stage, it can save a lot CPU cycles

...+- > include/standard-headers/linux/virtio_balloon.h | 1 + > include/sysemu/balloon.h | 10 ++- > 5 files changed, 134 insertions(+), 5 deletions(-) > +static int virtio_balloon_free_pages(void *opaque, > + unsigned long *free_pages_bitmap, > + unsigned long *free_pages_count) > +{ > + VirtIOBalloon *s = opaque; > + VirtIODevice *vdev = VIRTIO_DEVICE(s); > + VirtQueueElement *elem = s->free_pages_vq_elem; > + int len; > + > + if (!balloon_free_pages_support...

...oner to get information about pages that can be filtered out is too limited (there may be other ways to do this; we might be able to use cmma on s390, for example), and I don't like hardcoding to a specific method. What about the reverse approach: Code may register a handler that populates the free_pages_bitmap which is called during this stage? <I like the idea of filtering in general, but I haven't looked at the code yet> > + } > + > migration_bitmap_sync(); > qemu_mutex_unlock_ramlist(); > qemu_mutex_unlock_iothread();

Get the free pages information through virtio and filter out the free pages in the ram bulk stage. This can significantly reduce the total live migration time as well as network traffic. Signed-off-by: Liang Li <liang.z.li at intel.com> --- migration/ram.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 46 insertions(+), 6 deletions(-) diff --git