If the memory of guest OS is changed constantly, the live migration can not be ended ever for ever. We can use the command 'virsh migrate-setmaxdowntime' to control the live migration. But the value of maxdowntime is diffcult to calculate because it depends on the transfer speed of network and constantly changing memroy size. We need a easy way to control the live migration. This patch set add the support of auto cold migration fallback on timeout. With this patch set, when we migrate the guest OS, we can specify a timeout. If the live migration timeouts, the migration will fallback to cold migration. Test of this patchset on Linux: Env: a. The size of guest OS's memory: 1GB b. The transfer speed of network: about 100Mb/s c. The size of constantly changing memory: more than 900MB 1. migrate without timeout # virsh migrate --live RHEL6RC qemu+ssh://<dest IP>/system tcp://<dest IP>:49152 The migration does not end after 12 hours. 2. migrate with timeout(30 minutes): # date Wed Dec 15 09:39:23 CST 2010 # virsh migrate --live --timeout 1800 RHEL6RC qemu+ssh://<dest IP>/system tcp:<dest IP>:49152 # date Wed Dec 15 10:09:52 CST 2010 This patchset is not tested on Windows(I have no such environment). v2: - implemente timer for Windows - implemente dynamic timers Wen Congyang (2): timer impl auto cold migration fallback at timeout configure.ac | 4 + src/Makefile.am | 6 +- src/libvirt.c | 2 + src/libvirt_private.syms | 6 ++ src/util/timer.c | 166 ++++++++++++++++++++++++++++++++++++++++++++++ src/util/timer.h | 37 ++++++++++ src/util/timer_linux.c | 130 ++++++++++++++++++++++++++++++++++++ src/util/timer_win32.c | 128 +++++++++++++++++++++++++++++++++++ tools/virsh.c | 53 +++++++++++++++ 9 files changed, 530 insertions(+), 2 deletions(-) create mode 100644 src/util/timer.c create mode 100644 src/util/timer.h create mode 100644 src/util/timer_linux.c create mode 100644 src/util/timer_win32.c