Am 26.03.2015 um 15:54 hat Peter Lieven geschrieben: > Hi Block people, > > we recently observed some strange I/O stalls on some vServers. I suspect a > bug in the target and > already added some debugging output to libiscsi that could have helped to > track the issue. > > However, to enable this debugging I would need to call > > iscsi_set_log_level > > during runtime from the hmp or qmp. > > I wonder what would be the best way to do this and/or if it would be > interesting to have a generic > way to tell a block backend to enter debugging whereas I would leave it up to > the backend driver > what exactly that means? > > Other option would be to set an enviroment variable during runtime. But as > far as I know thats > not possible.
I think debugging should be controlled with driver-specific options to bdrv_open(). For changing the debugging options at runtime, we'd need to provide a way to directly call bdrv_reopen() from the monitor. Before this can work, we need some more infrastructure work that even introduces the concept of QDict *options to bdrv_reopen(). I have patches to do this, but even though that branch mostly works, it is still rather messy and not in a mergable state. If you're interested anyway, it's the blockdev branch in my tree. For your immediate case, you'll probably want a downstream ad-hoc hack rather than waiting for the real thing. Kevin