Add statistic counters and averages

blink/instruction.c

@@ -25,6 +25,7 @@
 #include "blink/macros.h"
 #include "blink/memory.h"
 #include "blink/modrm.h"
+#include "blink/stats.h"
 #include "blink/x86.h"
 
 static bool IsOpcodeEqual(struct XedDecodedInst *xedd, u8 *a) {
@@ -44,6 +45,7 @@ static bool IsOpcodeEqual(struct XedDecodedInst *xedd, u8 *a) {
 
 static void ReadInstruction(struct Machine *m, u8 *p, unsigned n) {
   struct XedDecodedInst xedd[1];
+  STATISTIC(instructions_decoded++);
   if (!DecodeInstruction(xedd, p, n, m->mode)) {
     memcpy(m->xedd, xedd, kInstructionBytes);
   } else {
@@ -55,6 +57,7 @@ static void LoadInstructionSlow(struct Machine *m, u64 ip) {
   unsigned i;
   u8 *addr;
   u8 copy[15], *toil;
+  STATISTIC(page_overlaps++);
   i = 4096 - (ip & 4095);
   addr = ResolveAddress(m, ip);
   if ((toil = FindReal(m, ip + i))) {
@@ -81,7 +84,9 @@ void LoadInstruction(struct Machine *m) {
       m->opcache->codehost = ResolveAddress(m, m->opcache->codevirt);
       addr = m->opcache->codehost + (ip & 4095);
     }
-    if (!IsOpcodeEqual(m->xedd, addr)) {
+    if (IsOpcodeEqual(m->xedd, addr)) {
+      STATISTIC(instructions_cached++);
+    } else {
       ReadInstruction(m, addr, 15);
     }
   } else {

blink/memory.c

@@ -27,6 +27,7 @@
 #include "blink/memory.h"
 #include "blink/pml4t.h"
 #include "blink/real.h"
+#include "blink/stats.h"
 
 void SetReadAddr(struct Machine *m, i64 addr, u32 size) {
   if (size) {
@@ -64,12 +65,14 @@ u64 FindPage(struct Machine *m, i64 virt) {
   virt &= -4096;
   for (i = 1; i < ARRAYLEN(m->tlb); ++i) {
     if (m->tlb[i].virt == virt && ((res = m->tlb[i].entry) & PAGE_V)) {
+      STATISTIC(++tlb_hits_2);
       bubble = m->tlb[i - 1];
       m->tlb[i - 1] = m->tlb[i];
       m->tlb[i] = bubble;
       return res;
     }
   }
+  STATISTIC(++tlb_misses);
   level = 39;
   entry = m->system->cr3;
   do {
@@ -94,6 +97,7 @@ u8 *FindReal(struct Machine *m, i64 virt) {
   u64 entry;
   if (m->mode != XED_MODE_REAL) {
     if (m->tlb[0].virt == (virt & -4096) && (m->tlb[0].entry & PAGE_V)) {
+      STATISTIC(++tlb_hits_1);
       return m->system->real.p + (m->tlb[0].entry & PAGE_TA) + (virt & 4095);
     }
     if (-0x800000000000 <= virt && virt < 0x800000000000) {
@@ -171,7 +175,10 @@ void VirtualRecvWrite(struct Machine *m, i64 addr, void *src, u64 n) {
 u8 *ReserveAddress(struct Machine *m, i64 v, size_t n) {
   u8 *r;
   unassert(n <= sizeof(m->opcache->stash));
-  if ((v & 4095) + n <= 4096) return ResolveAddress(m, v);
+  if ((v & 4095) + n <= 4096) {
+    return ResolveAddress(m, v);
+  }
+  STATISTIC(++page_overlaps);
   m->opcache->stashaddr = v;
   m->opcache->stashsize = n;
   r = m->opcache->stash;
@@ -184,7 +191,10 @@ u8 *AccessRam(struct Machine *m, i64 v, size_t n, void *p[2], u8 *tmp,
   u8 *a, *b;
   unsigned k;
   unassert(n <= 4096);
-  if ((v & 4095) + n <= 4096) return ResolveAddress(m, v);
+  if ((v & 4095) + n <= 4096) {
+    return ResolveAddress(m, v);
+  }
+  STATISTIC(++page_overlaps);
   k = 4096;
   k -= v & 4095;
   unassert(k <= 4096);

blink/stats.c

@@ -0,0 +1,42 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "blink/log.h"
+#include "blink/stats.h"
+
+#define DEFINE_AVERAGE(S) struct Average S;
+#define DEFINE_COUNTER(S) long S;
+#include "blink/stats.inc"
+#undef DEFINE_AVERAGE
+#undef DEFINE_COUNTER
+
+#define APPEND(...) o += snprintf(b + o, n - o, __VA_ARGS__)
+
+void PrintStats(void) {
+#ifndef NDEBUG
+  char b[2048];
+  int n = sizeof(b);
+  int o = 0;
+  b[0] = 0;
+#define DEFINE_COUNTER(S) APPEND("%-32s = %ld\n", #S, S);
+#define DEFINE_AVERAGE(S) APPEND("%-32s = %.6g\n", #S, S.a);
+#include "blink/stats.inc"
+#undef S
+  WriteErrorString(b);
+#endif
+}

blink/stats.h

@@ -0,0 +1,49 @@
+#ifndef BLINK_STATS_H_
+#define BLINK_STATS_H_
+#include "blink/tsan.h"
+
+#ifndef NDEBUG
+// we don't care about the accuracy of statistics across threads. some
+// hardware architectures don't even seem to have atomic addition ops.
+#define STATISTIC(x)      \
+  do {                    \
+    IGNORE_RACES_START(); \
+    x;                    \
+    IGNORE_RACES_END();   \
+  } while (0)
+#else
+#define STATISTIC(x) (void)0
+#endif
+
+#define AVERAGE(S, x) S.a += ((x)-S.a) / ++S.i
+
+#ifndef NDEBUG
+#ifdef __GNUC__
+#define GET_COUNTER(S)    \
+  ({                      \
+    IGNORE_RACES_START(); \
+    long S_ = S;          \
+    IGNORE_RACES_END();   \
+    S_;                   \
+  })
+#else
+#define GET_COUNTER(S) (S)
+#endif
+#else
+#define GET_COUNTER(S) 0L
+#endif
+
+#define DEFINE_COUNTER(S) extern long S;
+#define DEFINE_AVERAGE(S) extern struct Average S;
+#include "blink/stats.inc"
+#undef DEFINE_COUNTER
+#undef DEFINE_AVERAGE
+
+struct Average {
+  double a;
+  long i;
+};
+
+void PrintStats(void);
+
+#endif /* BLINK_STATS_H_ */

blink/stats.inc

@@ -0,0 +1,7 @@
+DEFINE_COUNTER(instructions_cached)
+DEFINE_COUNTER(instructions_decoded)
+DEFINE_COUNTER(instructions_dispatched)
+DEFINE_COUNTER(page_overlaps)
+DEFINE_COUNTER(tlb_hits_1)
+DEFINE_COUNTER(tlb_hits_2)
+DEFINE_COUNTER(tlb_misses)