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authorAndreas Hansson <andreas.hansson@arm.com>2012-08-28 14:30:31 -0400
committerAndreas Hansson <andreas.hansson@arm.com>2012-08-28 14:30:31 -0400
commitd53d04473e0d6ca1765f1117072eec59187a7f7b (patch)
treed336db3bfb308b14ec5bba88e8f4ddee1dde8899 /src/cpu/inorder/cpu.cc
parentd14e5857c7e1ee053fb4eb448c4776d7c985c5b2 (diff)
downloadgem5-d53d04473e0d6ca1765f1117072eec59187a7f7b.tar.xz
Clock: Rework clocks to avoid tick-to-cycle transformations
This patch introduces the notion of a clock update function that aims to avoid costly divisions when turning the current tick into a cycle. Each clocked object advances a private (hidden) cycle member and a tick member and uses these to implement functions for getting the tick of the next cycle, or the tick of a cycle some time in the future. In the different modules using the clocks, changes are made to avoid counting in ticks only to later translate to cycles. There are a few oddities in how the O3 and inorder CPU count idle cycles, as seen by a few locations where a cycle is subtracted in the calculation. This is done such that the regression does not change any stats, but should be revisited in a future patch. Another, much needed, change that is not done as part of this patch is to introduce a new typedef uint64_t Cycle to be able to at least hint at the unit of the variables counting Ticks vs Cycles. This will be done as a follow-up patch. As an additional follow up, the thread context still uses ticks for the book keeping of last activate and last suspend and this should probably also be changed into cycles as well.
Diffstat (limited to 'src/cpu/inorder/cpu.cc')
-rw-r--r--src/cpu/inorder/cpu.cc31
1 files changed, 14 insertions, 17 deletions
diff --git a/src/cpu/inorder/cpu.cc b/src/cpu/inorder/cpu.cc
index 4aff0c579..ec06f19f0 100644
--- a/src/cpu/inorder/cpu.cc
+++ b/src/cpu/inorder/cpu.cc
@@ -212,7 +212,7 @@ void
InOrderCPU::CPUEvent::scheduleEvent(int delay)
{
assert(!scheduled() || squashed());
- cpu->reschedule(this, cpu->nextCycle(curTick() + cpu->ticks(delay)), true);
+ cpu->reschedule(this, cpu->clockEdge(delay), true);
}
void
@@ -401,7 +401,7 @@ InOrderCPU::InOrderCPU(Params *params)
frontEndSked = createFrontEndSked();
faultSked = createFaultSked();
- lastRunningCycle = curTick();
+ lastRunningCycle = curCycle();
lockAddr = 0;
lockFlag = false;
@@ -761,17 +761,17 @@ InOrderCPU::tick()
if (!tickEvent.scheduled()) {
if (_status == SwitchedOut) {
// increment stat
- lastRunningCycle = curTick();
+ lastRunningCycle = curCycle();
} else if (!activityRec.active()) {
DPRINTF(InOrderCPU, "sleeping CPU.\n");
- lastRunningCycle = curTick();
+ lastRunningCycle = curCycle();
timesIdled++;
} else {
//Tick next_tick = curTick() + cycles(1);
//tickEvent.schedule(next_tick);
- schedule(&tickEvent, nextCycle(curTick() + 1));
+ schedule(&tickEvent, clockEdge(1));
DPRINTF(InOrderCPU, "Scheduled CPU for next tick @ %i.\n",
- nextCycle(curTick() + 1));
+ clockEdge(1));
}
}
@@ -959,15 +959,10 @@ InOrderCPU::scheduleCpuEvent(CPUEventType c_event, Fault fault,
CPUEvent *cpu_event = new CPUEvent(this, c_event, fault, tid, inst,
event_pri);
- Tick sked_tick = nextCycle(curTick() + ticks(delay));
- if (delay >= 0) {
- DPRINTF(InOrderCPU, "Scheduling CPU Event (%s) for cycle %i, [tid:%i].\n",
- eventNames[c_event], curTick() + delay, tid);
- schedule(cpu_event, sked_tick);
- } else {
- cpu_event->process();
- cpuEventRemoveList.push(cpu_event);
- }
+ Tick sked_tick = clockEdge(delay);
+ DPRINTF(InOrderCPU, "Scheduling CPU Event (%s) for cycle %i, [tid:%i].\n",
+ eventNames[c_event], curTick() + delay, tid);
+ schedule(cpu_event, sked_tick);
// Broadcast event to the Resource Pool
// Need to reset tid just in case this is a dummy instruction
@@ -1696,7 +1691,9 @@ InOrderCPU::wakeCPU()
DPRINTF(Activity, "Waking up CPU\n");
- Tick extra_cycles = tickToCycles((curTick() - 1) - lastRunningCycle);
+ Tick extra_cycles = curCycle() - lastRunningCycle;
+ if (extra_cycles != 0)
+ --extra_cycles;
idleCycles += extra_cycles;
for (int stage_num = 0; stage_num < NumStages; stage_num++) {
@@ -1705,7 +1702,7 @@ InOrderCPU::wakeCPU()
numCycles += extra_cycles;
- schedule(&tickEvent, nextCycle(curTick()));
+ schedule(&tickEvent, nextCycle());
}
// Lots of copied full system code...place into BaseCPU class?