Hi, qemuers: I found that the guest disk file cache mode will affect to the time of savevm.
the cache 'writeback' too slow. but the cache 'unsafe' is as fast as it can, less than 10 seconds. here is the example I use virsh: @cache with writeback: #the first snapshot real 0m21.904s user 0m0.006s sys 0m0.008s #the secondary snapshot real 2m11.624s user 0m0.013s sys 0m0.008s @cache with unsafe: #the first snapshot real 0m0.730s user 0m0.006s sys 0m0.005s #the secondary snapshot real 0m1.296s user 0m0.002s sys 0m0.008s so, what the difference between them when using different cache. the other question: when I change the buffer size #define IO_BUF_SIZE 32768 to #define IO_BUF_SIZE (1 * 1024 * 1024), the savevm is more quickly. thanks. xuanmao_001
