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Re: [Qemu-devel] [RFC PATCH V3 0/3] Multithread TCG async_safe_work part
Re: [Qemu-devel] [RFC PATCH V3 0/3] Multithread TCG async_safe_work part.
Mon, 20 Jul 2015 18:36:14 +0100
> From: KONRAD Frederic <address@hidden>
> This is the async_safe_work introduction bit of the Multithread TCG work.
> Rebased on current upstream (6169b60285fe1ff730d840a49527e721bfb30899).
> (Currently untested as I need to rebase MTTCG first.)
> It can be cloned here:
> http://git.greensocs.com/fkonrad/mttcg.git branch async_work_v3
> The first patch introduces a mutex to protect the existing queued_work_*
> CPUState members against multiple (concurent) access.
> The second patch introduces a tcg_exec_flag which will be 1 when we are inside
> cpu_exec(), -1 when we must not enter the cpu execution and 0 when we are
> allowed to do so. This is required as safe work need to be sure that's all
> are outside cpu_exec().
> The last patch introduces async_safe_work. It allows to add some work which
> be done asynchronously but only when all vCPUs are outside cpu_exec(). The tcg
> thread will wait that no vCPUs have any pending safe work before reentering
> Changes V2 -> V3:
> * Check atomically we are not in the executiong loop to fix the race
> which might happen.
> Changes V1 -> V2:
> * Release the lock while running the callback for both async and safe work.
> KONRAD Frederic (3):
> cpus: protect queued_work_* with work_mutex.
> cpus: add tcg_exec_flag.
> cpus: introduce async_run_safe_work_on_cpu.
Also currently breaks a lot of targets:
> cpu-exec.c | 10 ++++
> cpus.c | 160
> include/qom/cpu.h | 57 +++++++++++++++++++
> qom/cpu.c | 20 +++++++
> 4 files changed, 207 insertions(+), 40 deletions(-)