254 lines
6.7 KiB
C++
254 lines
6.7 KiB
C++
/*
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* \brief A multiplexable common instruction processor
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* \author Martin Stein
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* \author Stefan Kalkowski
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* \date 2014-01-14
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*/
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/*
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* Copyright (C) 2014 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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/* core includes */
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#include <kernel/processor.h>
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#include <kernel/processor_pool.h>
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#include <kernel/thread.h>
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#include <kernel/irq.h>
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#include <pic.h>
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#include <timer.h>
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namespace Kernel
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{
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/**
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* Lists all pending domain updates
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*/
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class Processor_domain_update_list;
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Pic * pic();
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Timer * timer();
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}
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class Kernel::Processor_domain_update_list
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:
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public Double_list<Processor_domain_update>
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{
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public:
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/**
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* Perform all pending domain updates on the executing processor
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*/
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void for_each_perform_locally()
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{
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for_each([] (Processor_domain_update * const domain_update) {
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domain_update->_perform_locally();
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});
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}
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};
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namespace Kernel
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{
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/**
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* Return singleton of the processor domain-udpate list
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*/
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Processor_domain_update_list * processor_domain_update_list()
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{
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static Processor_domain_update_list s;
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return &s;
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}
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}
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/**********************
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** Processor_client **
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**********************/
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void Kernel::Processor_client::_interrupt(unsigned const processor_id)
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{
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/* determine handling for specific interrupt */
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unsigned irq_id;
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Pic * const ic = pic();
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if (ic->take_request(irq_id)) {
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/* check wether the interrupt is a processor-scheduling timeout */
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if (!_processor->check_timer_interrupt(irq_id)) {
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/* check wether the interrupt is our inter-processor interrupt */
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if (ic->is_ip_interrupt(irq_id, processor_id)) {
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processor_domain_update_list()->for_each_perform_locally();
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_processor->ip_interrupt_handled();
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/* after all it must be a user interrupt */
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} else {
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/* try to inform the user interrupt-handler */
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Irq::occurred(irq_id);
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}
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}
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}
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/* end interrupt request at controller */
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ic->finish_request();
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}
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void Kernel::Processor_client::_schedule() { _processor->schedule(this); }
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/***************
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** Processor **
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***************/
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void Kernel::Processor::schedule(Processor_client * const client)
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{
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if (_id != executing_id()) {
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/*
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* Remote add client and let target processor notice it if necessary
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*
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* The interrupt controller might provide redundant submission of
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* inter-processor interrupts. Thus its possible that once the targeted
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* processor is able to grab the kernel lock, multiple remote updates
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* occured and consequently the processor traps multiple times for the
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* sole purpose of recognizing the result of the accumulative changes.
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* Hence, we omit further interrupts if there is one pending already.
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* Additionailly we omit the interrupt if the insertion doesn't
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* rescind the current scheduling choice of the processor.
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*/
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if (_scheduler.insert_and_check(client)) { trigger_ip_interrupt(); }
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} else {
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/* add client locally */
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_scheduler.insert(client);
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}
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}
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void Kernel::Processor::trigger_ip_interrupt()
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{
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if (!_ip_interrupt_pending) {
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pic()->trigger_ip_interrupt(_id);
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_ip_interrupt_pending = true;
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}
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}
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void Kernel::Processor_client::_unschedule()
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{
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assert(_processor->id() == Processor::executing_id());
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_processor->scheduler()->remove(this);
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}
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void Kernel::Processor_client::_yield()
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{
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assert(_processor->id() == Processor::executing_id());
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_processor->scheduler()->yield_occupation();
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}
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/*****************************
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** Processor_domain_update **
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*****************************/
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void Kernel::Processor_domain_update::_perform_locally()
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{
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/* perform domain update locally and get pending bit */
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unsigned const processor_id = Processor::executing_id();
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if (!_pending[processor_id]) { return; }
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_domain_update();
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_pending[processor_id] = false;
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/* check wether there are still processors pending */
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unsigned i = 0;
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for (; i < PROCESSORS && !_pending[i]; i++) { }
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if (i < PROCESSORS) { return; }
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/* as no processors pending anymore, end the domain update */
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processor_domain_update_list()->remove(this);
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_processor_domain_update_unblocks();
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}
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bool Kernel::Processor_domain_update::_perform(unsigned const domain_id)
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{
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/* perform locally and leave it at that if in uniprocessor mode */
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_domain_id = domain_id;
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_domain_update();
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if (PROCESSORS == 1) { return false; }
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/* inform other processors and block until they are done */
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processor_domain_update_list()->insert_tail(this);
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unsigned const processor_id = Processor::executing_id();
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for (unsigned i = 0; i < PROCESSORS; i++) {
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if (i == processor_id) { continue; }
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_pending[i] = true;
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processor_pool()->processor(i)->trigger_ip_interrupt();
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}
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return true;
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}
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void Kernel::Processor::exception()
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{
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/*
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* Request the current occupant without any update. While the
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* processor was outside the kernel, another processor may have changed the
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* scheduling of the local activities in a way that an update would return
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* an occupant other than that whose exception caused the kernel entry.
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*/
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Processor_client * const old_client = _scheduler.occupant();
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Cpu_lazy_state * const old_state = old_client->lazy_state();
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old_client->exception(_id);
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/*
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* The processor local as well as remote exception-handling may have
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* changed the scheduling of the local activities. Hence we must update the
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* occupant.
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*/
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bool updated, refreshed;
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Processor_client * const new_client =
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_scheduler.update_occupant(updated, refreshed);
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/**
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* There are three scheduling situations we have to deal with:
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*
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* The client has not changed and didn't yield:
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*
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* The client must not update its time-slice state as the timer
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* can continue as is and hence keeps providing the information.
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*
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* The client has changed or did yield and the previous client
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* received a fresh timeslice:
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*
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* The previous client can reset his time-slice state.
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* The timer must be re-programmed according to the time-slice
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* state of the new client.
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*
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* The client has changed and the previous client did not receive
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* a fresh timeslice:
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*
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* The previous client must update its time-slice state. The timer
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* must be re-programmed according to the time-slice state of the
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* new client.
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*/
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if (updated) {
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unsigned const tics_per_slice = _tics_per_slice();
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if (refreshed) { old_client->reset_tics_consumed(); }
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else {
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unsigned const tics_left = _timer->value(_id);
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old_client->update_tics_consumed(tics_left, tics_per_slice);
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}
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_update_timer(new_client->tics_consumed(), tics_per_slice);
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}
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/**
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* Apply the CPU state of the new client and continue his execution
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*/
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Cpu_lazy_state * const new_state = new_client->lazy_state();
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prepare_proceeding(old_state, new_state);
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new_client->proceed(_id);
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}
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