On 2013-07-25 14:41, Stefan Hajnoczi wrote: > On Thu, Jul 25, 2013 at 2:38 PM, Jan Kiszka <jan.kis...@siemens.com> wrote: >> On 2013-07-25 14:35, Paolo Bonzini wrote: >>> Il 25/07/2013 14:32, Jan Kiszka ha scritto: >>>> On 2013-07-25 14:21, Alex Bligh wrote: >>>>> >>>>> >>>>> --On 25 July 2013 14:05:30 +0200 Stefan Hajnoczi <stefa...@gmail.com> >>>>> wrote: >>>>> >>>>>> Alex Bligh's series gives each AioContext its own rt_clock. This avoids >>>>>> the need for synchronization in the simple case. If we require timer >>>>>> access between threads then we really need to synchronize. >>>>>> >>>>>> You pointed out in another email that vm_clock stops when the guest is >>>>>> paused. I think we can find a solution for I/O throttling and QED, >>>>>> which use vm_clock in the block layer. Note that block jobs already use >>>>>> rt_clock. >>>>> >>>>> I would happily at a QEMUClock of each type to AioContext. They are after >>>>> all pretty lightweight. >>>> >>>> What's the point of adding tones of QEMUClock instances? Considering >>>> proper abstraction, how are they different for each AioContext? Will >>>> they run against different clock sources, start/stop at different times? >>>> If the answer is "they have different timer list", then fix this >>>> incorrect abstraction. >>> >>> s/QEMUClock/QEMUTimerList/ ? :) >> >> What do you mean? If the content of struct QEMUClock remained the same, >> that would just paper over a design mistake. > > QEMUClock really isn't much more than a reference to a clock source, > an enabled/disabled flag, and a timer list. > > The point of having one QEMUClock per AioContext is to allow each > thread's event loop to have its own timers, without synchronization. > > What is the design mistake? I only see poor naming.
The concept of clocks (with start/stop property) and active timers shall not be mixed, they are independent. Just factor out a separate list of running timers and pass that to the infrastructure that deals with them. I attached them to a QEMUAlarmTimer instance, you will likely need a different abstraction. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux
