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Re: [Qemu-devel] [PATCH v6 3/7] trace: [tcg] Delay changes to dynamic st
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v6 3/7] trace: [tcg] Delay changes to dynamic state when translating |
Date: |
Wed, 11 Jan 2017 16:16:40 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Tue, Jan 10, 2017 at 05:31:37PM +0100, Paolo Bonzini wrote:
> On 09/01/2017 18:01, Stefan Hajnoczi wrote:
> > Or use a simpler scheme:
> >
> > struct CPUState {
> > ...
> > uint32_t dstate_update_count;
> > };
> >
> > In trace_event_set_vcpu_state_dynamic():
> >
> > if (state) {
> > trace_events_enabled_count++;
> > set_bit(vcpu_id, vcpu->trace_dstate_delayed);
> > atomic_inc(&vcpu->dstate_update_count, 1);
> > (*ev->dstate)++;
> > } ...
> >
> > In cpu_exec() and friends:
> >
> > last_dstate_update_count = atomic_read(&vcpu->dstate_update_count);
> >
> > tb = tb_find(cpu, last_tb, tb_exit);
> > cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit, &sc);
> >
> > /* apply and disable delayed dstate changes */
> > if (unlikely(atomic_read(&cpu->dstate_update_count) !=
> > last_dstate_update_count)) {
> > bitmap_copy(cpu->trace_dstate, cpu->trace_dstate_delayed,
> > trace_get_vcpu_event_count());
> > }
> >
> > (You'll need to adjust the details but the update counter approach
> > should be workable.)
>
> Would it work to use async_run_on_cpu?
I think so.
Stefan
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