| Message ID | 20180111082738.27295.80055.stgit@pasha-VirtualBox |
|---|---|
| State | New |
| Headers | show |
| Series | replay additions | expand |
On 11/01/2018 09:27, Pavel Dovgalyuk wrote: > + } else { > + qemu_notify_event(); > + } Before this patch, what would do the qemu_notify_event? Thanks, Paolo > /* Does not need atomic_mb_set because a spurious wakeup is okay. */
> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini > On 11/01/2018 09:27, Pavel Dovgalyuk wrote: > > + } else { > > + qemu_notify_event(); > > + } > > Before this patch, what would do the qemu_notify_event? We tried using qemu_notify_event to wake up the iothread and speedup the replay, when there is no work for vcpu thread to do. Pavel Dovgalyuk
On 11/01/2018 14:12, Pavel Dovgalyuk wrote: >> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini >> On 11/01/2018 09:27, Pavel Dovgalyuk wrote: >>> + } else { >>> + qemu_notify_event(); >>> + } >> >> Before this patch, what would do the qemu_notify_event? > > We tried using qemu_notify_event to wake up the iothread and speedup the replay, > when there is no work for vcpu thread to do. But why doesn't the iothread wake up on its own? Paolo
> From: Paolo Bonzini [mailto:pbonzini@redhat.com] > On 11/01/2018 14:12, Pavel Dovgalyuk wrote: > >> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini > >> On 11/01/2018 09:27, Pavel Dovgalyuk wrote: > >>> + } else { > >>> + qemu_notify_event(); > >>> + } > >> > >> Before this patch, what would do the qemu_notify_event? > > > > We tried using qemu_notify_event to wake up the iothread and speedup the replay, > > when there is no work for vcpu thread to do. > > But why doesn't the iothread wake up on its own? It will wake up by timeout. But with this change this happens sooner and replay goes faster. Pavel Dovgalyuk
On 12/01/2018 07:13, Pavel Dovgalyuk wrote: >> From: Paolo Bonzini [mailto:pbonzini@redhat.com] >> On 11/01/2018 14:12, Pavel Dovgalyuk wrote: >>>> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini >>>> On 11/01/2018 09:27, Pavel Dovgalyuk wrote: >>>>> + } else { >>>>> + qemu_notify_event(); >>>>> + } >>>> >>>> Before this patch, what would do the qemu_notify_event? >>> >>> We tried using qemu_notify_event to wake up the iothread and speedup the replay, >>> when there is no work for vcpu thread to do. >> >> But why doesn't the iothread wake up on its own? > > It will wake up by timeout. But with this change this happens sooner and replay goes faster. If you want replays to ignore timeouts, that should be done by ensuring that qemu-timer.c passes a zero timeout to main-loop.c. (It probably should be optional, too, maybe via -icount sleep). Paolo
> From: Paolo Bonzini [mailto:pbonzini@redhat.com] > On 12/01/2018 07:13, Pavel Dovgalyuk wrote: > >> From: Paolo Bonzini [mailto:pbonzini@redhat.com] > >> On 11/01/2018 14:12, Pavel Dovgalyuk wrote: > >>>> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini > >>>> On 11/01/2018 09:27, Pavel Dovgalyuk wrote: > >>>>> + } else { > >>>>> + qemu_notify_event(); > >>>>> + } > >>>> > >>>> Before this patch, what would do the qemu_notify_event? > >>> > >>> We tried using qemu_notify_event to wake up the iothread and speedup the replay, > >>> when there is no work for vcpu thread to do. > >> > >> But why doesn't the iothread wake up on its own? > > > > It will wake up by timeout. But with this change this happens sooner and replay goes faster. > > If you want replays to ignore timeouts, that should be done by ensuring > that qemu-timer.c passes a zero timeout to main-loop.c. (It probably > should be optional, too, maybe via -icount sleep). Making it optional is a good one. I'll exclude this patch from the series for working on it later. Pavel Dovgalyuk
diff --git a/cpus.c b/cpus.c index bafedfc..ef4c5b9 100644 --- a/cpus.c +++ b/cpus.c @@ -1449,39 +1449,43 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg) cpu = first_cpu; } - while (cpu && !cpu->queued_work_first && !cpu->exit_request) { + if (!replay_has_checkpoint()) { + while (cpu && !cpu->queued_work_first && !cpu->exit_request) { - atomic_mb_set(&tcg_current_rr_cpu, cpu); - current_cpu = cpu; + atomic_mb_set(&tcg_current_rr_cpu, cpu); + current_cpu = cpu; - qemu_clock_enable(QEMU_CLOCK_VIRTUAL, - (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0); + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, + (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0); - if (cpu_can_run(cpu)) { - int r; + if (cpu_can_run(cpu)) { + int r; - prepare_icount_for_run(cpu); + prepare_icount_for_run(cpu); - r = tcg_cpu_exec(cpu); + r = tcg_cpu_exec(cpu); - process_icount_data(cpu); + process_icount_data(cpu); - if (r == EXCP_DEBUG) { - cpu_handle_guest_debug(cpu); - break; - } else if (r == EXCP_ATOMIC) { - cpu_exec_step_atomic(cpu); + if (r == EXCP_DEBUG) { + cpu_handle_guest_debug(cpu); + break; + } else if (r == EXCP_ATOMIC) { + cpu_exec_step_atomic(cpu); + break; + } + } else if (cpu->stop) { + if (cpu->unplug) { + cpu = CPU_NEXT(cpu); + } break; } - } else if (cpu->stop) { - if (cpu->unplug) { - cpu = CPU_NEXT(cpu); - } - break; - } - cpu = CPU_NEXT(cpu); - } /* while (cpu && !cpu->exit_request).. */ + cpu = CPU_NEXT(cpu); + } /* while (cpu && !cpu->exit_request).. */ + } else { + qemu_notify_event(); + } /* Does not need atomic_mb_set because a spurious wakeup is okay. */ atomic_set(&tcg_current_rr_cpu, NULL); diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h index d026b28..44c1ff7 100644 --- a/include/sysemu/replay.h +++ b/include/sysemu/replay.h @@ -122,6 +122,9 @@ void replay_shutdown_request(ShutdownCause cause); Returns 0 in PLAY mode if checkpoint was not found. Returns 1 in all other cases. */ bool replay_checkpoint(ReplayCheckpoint checkpoint); +/*! Used to determine that checkpoint is pending. + Does not proceed to the next event in the log. */ +bool replay_has_checkpoint(void); /* Asynchronous events queue */ diff --git a/replay/replay.c b/replay/replay.c index c9fd984..b9c496a 100644 --- a/replay/replay.c +++ b/replay/replay.c @@ -219,6 +219,19 @@ out: return res; } +bool replay_has_checkpoint(void) +{ + bool res = false; + if (replay_mode == REPLAY_MODE_PLAY) { + replay_mutex_lock(); + replay_account_executed_instructions(); + res = EVENT_CHECKPOINT <= replay_state.data_kind + && replay_state.data_kind <= EVENT_CHECKPOINT_LAST; + replay_mutex_unlock(); + } + return res; +} + void replay_init_locks(void) { replay_mutex_init();