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Re: [Qemu-devel] [PATCH v5 3/4] Plumb the HAXM-based hardware accelerati

From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH v5 3/4] Plumb the HAXM-based hardware acceleration support
Date: Thu, 5 Jan 2017 15:01:45 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1

On 05/01/2017 14:50, Vincent Palatin wrote:
> Sorry I missed it.
> I move it to qemu_cpu_kick() as asked in the Darwin patch.
>> Apart from the above change, can you check if there are some less
>> heavyeight methods to force an exit?  I can think of QueueUserAPC with
>> an empty pfnAPC here, and SleepEx(0, TRUE) in qemu_hax_cpu_thread_fn
>> before qemu_wait_io_event_common.
> Actually I don't know a good test case to verify such a change, any advice ?

Try computing the latency between qemu_cpu_kick and the exit from HAXM.
That is, something like

    int64_t kick_time = -1;

    atomic_set(&kick_time, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));

before SuspendThread or respectively QueueUserAPC, and

    extern volatile int64_t kick_time;

    int64_t kicked = atomic_xchg(&kick_time, -1);
    if (kicked != -1) {
               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - kicked);

right after hax_vcpu_run.    As long as the printed values remain
smallish, it's okay.

If you don't get any output, passing "info cpus" repeatedly to the QEMU
monitor will force a kick.


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