On Mon, Aug 26, 2013 at 09:59:51PM -0500, Yaodong Yang wrote: > In sum, the bdrv_co_do_readv() seems to be executed inside two thread, the > migration thread and native iothread. Both of them executed the function > twice for a single request. Could someone explain it for me ? I appreciate it > very much!
Did you check the bdrv_co_readv(bs=...) argument? The calls may be referring to two different BlockDriverState instances. A raw image file looks like this: BDS#1 (block/raw.c) ->backing_hd = NULL ->file = BDS#2 BDS#2 (block/raw-posix.c) With qcow2 and no backing file you would have something like this: BDS#1 (block/qcow2.c) ->backing_hd = NULL ->file = BDS#2 BDS#2 (block/raw-posix.c) Expect to see calls forwarded from BDS#1 to BDS#2. Stefan
