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Re: [Qemu-devel] [PATCH v3 3/5] replay: introduce new checkpoint for ico
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v3 3/5] replay: introduce new checkpoint for icount warp |
Date: |
Thu, 10 Mar 2016 11:24:21 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 10/03/2016 10:10, Pavel Dovgalyuk wrote:
>> > The start would be where you call qemu_clock_warp(QEMU_CLOCK_VIRTUAL,
>> > false):
>> >
>> > if (!use_icount) {
>> > return;
>> > }
>> > if (!runstate_is_running()) {
>> > return;
>> > }
>> > if (!replay_checkpoint(CHECKPOINT_CLOCK_WARP_START)) {
>> > return;
>> > }
>> > /* I think calling icount_warp_rt here is unnecessary. */
>> > if (!all_cpu_threads_idle()) {
>> > return;
>> > }
>> > if (qtest_enabled()) {
>> > /* When testing, qtest commands advance icount. */
>> > return;
>> > }
>> >
>> > /* We want to use the earliest deadline from ALL vm_clocks */
>> > clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
>> > deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
>> > ...
>> >
>> > The end or account function, instead, would be called from tcg_exec_all()
>> > and also from icount_dummy_timer() (this is what makes the call to
>> > icount_warp_rt unnecessary above):
> Why icount_warp_rt is unnecessary? There is no code to proceed the virtual
> clock.
> Then qemu_start_warp_timer will forever setup the timer without any progress.
If icount_warp_rt is called from icount_dummy_timer(), the virtual clock
will be updated as soon as the VIRTUAL_RT clock reaches the deadline.
It's a much more reasonable place to call icount_warp_rt from (if it
works...).
Paolo