Re: [Qemu-devel] [PATCH 0/8] Make icount thread-safe

["Andreas Färber" <afaerber@suse.de>]

Am 08.10.2013 10:47, schrieb Paolo Bonzini:
> This series moves the icount state under the same seqlock as the "normal"
> vm_clock implementation.
> 
> It is not yet 100% thread-safe, because the CPU list should be moved
> under RCU protection (due to the call to !all_cpu_threads_idle()
> in qemu_clock_warp).  However it is a substantial step forward, the
> only uncovered case being CPU hotplug.
> 
> Please review.
> 
> Paolo
> 
> Paolo Bonzini (8):
>   timers: extract timer_mod_ns_locked and timerlist_rearm
>   timers: add timer_mod_anticipate and timer_mod_anticipate_ns

>   timers: use cpu_get_icount() directly
>   timers: reorganize icount_warp_rt
>   timers: prepare the code for future races in calling qemu_clock_warp
>   timers: introduce cpu_get_clock_locked
>   timers: document (future) locking rules for icount
>   timers: make icount thread-safe

These patches touch cpus.c exclusively, so "timers:" is rather misleading.

As you know I have pending patches (in need of rebase due to the
performance issue you raised) moving the icount CPU fields around.
Is there anything in particular I should be aware of? Looks to me as if
this may be orthogonal?

What about the previous patch disabling icount for -smp? Does this
series supersede it or does it fix different concurrency issues?

Thanks,
Andreas

>  cpus.c                 | 110 ++++++++++++++++++++++++++++++++++++-------------
>  include/qemu/timer.h   |  26 +++++++++
>  qemu-timer.c           |  74 +++++++++++++++++++------
>  4 files changed, 163 insertions(+), 47 deletions(-)
>  create mode 100644 include/qemu/seqlock.h

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