On 2012-02-15 10:35, Wen Congyang wrote: > At 02/15/2012 05:21 PM, Jan Kiszka Wrote: >> On 2012-02-15 10:22, Wen Congyang wrote: >>> At 02/15/2012 05:07 PM, Jan Kiszka Wrote: >>>> On 2012-02-15 04:47, Wen Congyang wrote: >>>>> At 02/15/2012 02:27 AM, Jan Kiszka Wrote: >>>>>> On 2012-02-14 19:05, Jan Kiszka wrote: >>>>>>> On 2012-02-09 04:28, Wen Congyang wrote: >>>>>>>> The new monitor command dump may take long time to finish. So we need >>>>>>>> run it >>>>>>>> at the background. >>>>>>> >>>>>>> How does it work? Like live migration, i.e. you retransmit (overwrite) >>>>>>> already written but then dirtied pages? Hmm... no. >>>>>>> >>>>>>> What does background mean then? What is the use case? What if the user >>>>>>> decides to resume the vm? >>>>>> >>>>>> OK, that is addressed in patch 15! I would suggest merging it into this >>>>>> patch. It makes sense to handle that case gracefully right from the >>>>>> beginning. >>>>> >>>>> OK, I will merge it. >>>>> >>>>>> >>>>>> OK, now I have some other question: What is the point of rate-limiting >>>>>> the dump? The guest is not running, thus not competing for bandwidth. >>>>> >>>>> I use bandwidth to try to control the writing speed. If we write the >>>>> vmcore >>>>> to disk in a high speed, it may affect some other appilications which use >>>>> the same disk too. >>>> >>>> Just like the guest of that particular VM can do. I don't think we need >>>> this level of control here, it will be provided (if required) at a >>>> different level, affecting the whole QEMU process. Removing the vmcore >>>> bandwidth control will simplify code and user interface. >>> >>> OK. I will implementing it like this: >>> 1. write 100ms >>> 2. sleep 100ms(allow qemu to do the other things) >>> 3. goto 1 >> >> Why? Just write as fast as possible. > > If the memory is too big, the command will take too long time. > Eric said: > It sounds like it is long-running, which > means it probably needs to be asynchronous, as well as issue an event > upon completion, so that other monitor commands can be issued in the > meantime.
Asynchronous doesn't mean throttled. It means not waiting for potentially long-running I/O in the context of the monitor, but becoming interactive again. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux
