bitkeeper revision 1.1159.212.118 (420808adQbNXWTSEhY2Rqu5ALqDF5Q)

- Detect the CPU speed automatically, rather than having the user 
  specify a ips in bochsrc. The user can still specify it to override
  the auto-detected value.

- Care should be taken to make sure that tsc_per_bx_tick is not too
  small or too big. Otherwise, numerical precision issues may result
  in the wrong calculation of elapsed time

Signed-off-by: Edwin Zhai <edwin.zhai@intel.com>
Signed-off-by: Arun Sharma <arun.sharma@intel.com>
Signed-off-by: ian@xensource.com

tools/examples/bochsrc

@@ -16,4 +16,3 @@ error: action=report
 panic: action=ask
 
 mouse: enabled=0
-ips: 1500000

tools/ioemu/include/pc_system.h

@@ -45,6 +45,13 @@ BOCHSAPI extern class bx_pc_system_c bx_pc_system;
 extern double m_ips;
 #endif
 
+#ifdef BX_USE_VMX
+extern unsigned int tsc_per_bx_tick;
+
+#define rdtscll(val) \
+     __asm__ __volatile__("rdtsc" : "=A" (val))
+#endif
+
 class BOCHSAPI bx_pc_system_c : private logfunctions {
 private:
 
@@ -87,6 +94,26 @@ private:
   double     m_ips; // Millions of Instructions Per Second
 #endif
 
+#ifdef BX_USE_VMX
+  static Bit64s get_clock(void) {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return tv.tv_sec * 1000000LL + tv.tv_usec;
+    }
+
+  static Bit64u cpu_calibrate_ticks(void) {
+    Bit64s usec, t1, t2;
+
+    usec = get_clock();
+    rdtscll(t1);
+
+    usleep(50 * 1000);
+    usec = get_clock() - usec;
+    rdtscll(t2);
+
+    return (((t2 - t1) * 1000000LL + (usec >> 1)) / usec);
+    }
+#endif
   // This handler is called when the function which decrements the clock
   // ticks finds that an event has occurred.
   void   countdownEvent(void);

tools/ioemu/iodev/cpu.cc

@@ -167,9 +167,6 @@ bx_cpu_c::timer_handler(void)
 #define rdtscl(low) \
      __asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")
 
-#define rdtscll(val) \
-     __asm__ __volatile__("rdtsc" : "=A" (val))
-
 void
 bx_cpu_c::cpu_loop(int max_instr_count)
 {
@@ -211,9 +208,9 @@ bx_cpu_c::cpu_loop(int max_instr_count)
 #endif
 
 		if (t2 <= t1)
-			BX_TICKN((t2 + ULONGLONG_MAX - t1));
+			BX_TICKN((t2 + ULONGLONG_MAX - t1) / tsc_per_bx_tick);
 		else
-			BX_TICKN((t2 - t1));
+			BX_TICKN((t2 - t1) / tsc_per_bx_tick);
 		t1 = t2;
 
 		timer_handler();

tools/ioemu/iodev/pc_system.cc

@@ -44,6 +44,10 @@ unsigned long ips_count=0;
 double     m_ips; // Millions of Instructions Per Second
 #endif
 
+#ifdef BX_USE_VMX
+unsigned int tsc_per_bx_tick;
+#endif
+
 // Option for turning off BX_TIMER_DEBUG?
 // Check out m_ips and ips
 
@@ -98,6 +102,16 @@ bx_pc_system_c::init_ips(Bit32u ips)
   a20_mask   = 0xffffffff;
 #endif
 
+#ifdef BX_USE_VMX
+  Bit64u phy_cpu_freq = cpu_calibrate_ticks();
+ 
+  if (ips == 500000) {  //default ips: we use fixed scaling factor to calulate ips
+    tsc_per_bx_tick = 2000;
+    ips = phy_cpu_freq / tsc_per_bx_tick;
+  } else  //use uesr defined ips to calulate factor
+    tsc_per_bx_tick = ((phy_cpu_freq + (ips>>1)) / ips);
+#endif
+
   // parameter 'ips' is the processor speed in Instructions-Per-Second
   m_ips = double(ips) / 1000000.0L;