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Date: Wed, 7 Aug 2013 11:43:58 -0400 (EDT)
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [RFC] [PATCHv6 00/16] aio / timers: Add AioContext
 timers and use ppoll
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Alex Bligh <alex@alex.org.uk>, qemu-devel@nongnu.org, liu ping fan <qemulist@gmail.com>, Stefan Hajnoczi <stefanha@redhat.com>, MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>, rth@twiddle.net

> For anyone wishing to review this series, here's a diagram showing the
> new relationships and a summary of this series:
> 
> http://vmsplice.net/~stefan/timerlist.jpg
> 
> TimerList is the list of QEMUTimers which are pending on a QEMUClock
> clock source.

I just started reviewing this and the diagram may be different in
v7, anyway: why do you need a default TimerListGroup?  I would have
thought it is enough to use the default AioContext's own TLG.

Paolo

> Previously QEMUClock contained this list inline but the goal is to let
> AioContexts have their own independent timer lists.  This makes timers
> much more thread-friendly since we don't work on global lists and
> callbacks are dispatched in the same thread's AioContext where they were
> created.
> 
> TimerListGroup holds a timerlist for each clock source ("rt", "vm", and
> "host").  The main loop has the default TimerListGroup.  Each AioContext
> has its own TimerListGroup.
> 
> The other major change is that QEMU now uses the event loop's poll()
> timeout value instead of a separate OS-specific timer mechanism (aka the
> "alarm timer").
> 
> Stefan
>