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Being a bit more efficient in how hot traces gets tracked.

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This commit is contained in:
Florian Nücke
2020-09-16 09:31:52 +02:00
parent a2068c477f
commit b8a64ffc90
1 changed files with 27 additions and 32 deletions
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59
src/main/java/li/cil/circuity/vm/riscv/R5CPU.java
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@@ -80,6 +80,11 @@ public class R5CPU implements Steppable, RealTimeCounter, InterruptController {
// Translation look-aside buffer config.
private static final int TLB_SIZE = 256; // Must be a power of two for fast modulo via `& (TLB_SIZE - 1)`.
// Knobs for tweaking dynamic binary translation.
private static final int HOT_TRACE_COUNT = 16; // Must be a power of to for (x - 1) masking.
private static final int TRACE_COUNT_THRESHOLD = 30;
private static final int EXPECTED_MAX_TRACE_COUNT = 1024;
///////////////////////////////////////////////////////////////////
// RV32I
public int pc; // Program counter.
@@ -139,17 +144,8 @@ public class R5CPU implements Steppable, RealTimeCounter, InterruptController {
///////////////////////////////////////////////////////////////////
// Dynamic binary translation
private static final int MAX_TRACKED_TRACES = 50;
private static final int MAX_TRACES = 1000;
private static final int TRACE_COUNT_THRESHOLD = 20;
private final HotTrace[] hotTraces = new HotTrace[MAX_TRACKED_TRACES];
private final Int2ObjectMap<Trace> traces = new Int2ObjectOpenHashMap<>(MAX_TRACES);
private TraceClassLoader traceClassLoader = new TraceClassLoader();
private static final class HotTrace {
public int pc = -1;
public int count;
}
private final HotTrace[] hotTraces = new HotTrace[HOT_TRACE_COUNT];
private final Int2ObjectMap<Trace> traces = new Int2ObjectOpenHashMap<>(EXPECTED_MAX_TRACE_COUNT);
@FunctionalInterface
public interface Trace {
@@ -1029,31 +1025,21 @@ public class R5CPU implements Steppable, RealTimeCounter, InterruptController {
// return true;
if (traces.containsKey(pc)) {
traces.get(pc).execute(this);
invokeTrace(traces.get(pc));
return true;
} else {
int writeTrace = 0;
int writeTraceCount = hotTraces[0].count;
for (int i = 1; i < hotTraces.length && hotTraces[writeTrace].pc != pc; i++) {
final int count = hotTraces[i].count;
if (count < writeTraceCount || hotTraces[i].pc == pc) {
writeTrace = i;
writeTraceCount = count;
}
}
final int hotTraceIndex = (pc >> 1) & (HOT_TRACE_COUNT - 1);
final HotTrace hotTrace = hotTraces[hotTraceIndex];
if (hotTrace.pc != pc) {
hotTrace.pc = pc;
hotTrace.count = 1;
} else if (++hotTrace.count >= TRACE_COUNT_THRESHOLD) {
hotTrace.pc = -1;
if (hotTraces[writeTrace].pc != pc) {
hotTraces[writeTrace].pc = pc;
hotTraces[writeTrace].count = 0;
}
hotTraces[writeTrace].count++;
if (hotTraces[writeTrace].count >= TRACE_COUNT_THRESHOLD) {
final Trace trace = traceClassLoader.translateTrace(pc);
final Trace trace = translateTrace(pc);
traces.put(pc, trace);
hotTraces[writeTrace].pc = -1;
hotTraces[writeTrace].count = 0;
trace.execute(this);
invokeTrace(trace);
return true;
}
}
@@ -1061,6 +1047,10 @@ public class R5CPU implements Steppable, RealTimeCounter, InterruptController {
return false;
}
private void invokeTrace(final Trace trace) throws R5Exception, MemoryAccessException {
trace.execute(this);
}
private void interpret() throws R5Exception, MemoryAccessException {
// The idea here is to run many sequential instructions with very little overhead.
// We only need to exit the inner loop when we either leave the page we started in,
@@ -3367,6 +3357,11 @@ public class R5CPU implements Steppable, RealTimeCounter, InterruptController {
public MemoryMappedDevice device;
}
private static final class HotTrace {
public int pc = -1;
public int count;
}
public R5CPUStateSnapshot getState() {
final R5CPUStateSnapshot state = new R5CPUStateSnapshot();