sim: remove CONFIG_SIM_WALLTIME fast timing maybe harmful for IOs

Change-Id: Ic4ff5ec0aa99d2d229a07c4d1a9a4dae738d3cd9
Signed-off-by: ligd <liguiding1@xiaomi.com>

arch/sim/Kconfig

@@ -105,11 +105,6 @@ config SIM_X8664_MICROSOFT
 
 endchoice
 
-config SIM_WALLTIME
-	bool "Run the simulation at a fixed cadence in near real-time"
-	default y
-
-if SIM_WALLTIME
 choice
 	prompt "Simulation at a fixed cadence in near real-time"
 	default SIM_WALLTIME_SLEEP
@@ -117,12 +112,7 @@ choice
 config SIM_WALLTIME_SLEEP
 	bool "Execution the simulation in near real-time using host sleep"
 	---help---
-		NOTE:  In order to facility fast testing, the sim target's IDLE loop, by default,
-		calls the system timer "interrupt handler" as fast as possible.  As a result, there
-		really are no noticeable delays when a task sleeps.  However, the task really does
-		sleep -- but the time scale is wrong.  If you want behavior that is closer to
-		normal timing, then you can define SIM_WALLTIME=y in your configuration
-		file.  This configuration setting will cause the sim target's IDLE loop to delay
+		NOTE: This configuration setting will cause the sim target's IDLE loop to delay
 		on each call so that the system "timer interrupt" is called at a rate approximately
 		correct for the system timer tick rate.  With this definition in the configuration,
 		sleep() behavior is more or less normal.
@@ -137,14 +127,12 @@ config SIM_WALLTIME_SIGNAL
 
 endchoice
 
-endif
-
 config SIM_NETDEV
 	bool "Simulated Network Device"
 	default y
 	select ARCH_HAVE_NETDEV_STATISTICS
 	select SCHED_LPWORK
-	depends on (NET_ETHERNET && SIM_WALLTIME)
+	depends on NET_ETHERNET
 	---help---
 		Build in support for a simulated network device.
 
@@ -238,7 +226,6 @@ config SIM_X11FB
   bool "X11 graphics/input"
   default n
   select SCHED_LPWORK
-	depends on SIM_WALLTIME
 	---help---
 		Use X11 to provide graphics and input emulation to interact with host.
 
@@ -535,7 +522,7 @@ config SIM_QSPIFLASH_PAGESIZE
 choice
 	prompt "Simulated Prototype of HCI"
 	default SIM_HCISOCKET
-	depends on (HOST_LINUX && SIM_WALLTIME)
+	depends on HOST_LINUX
 
 config SIM_HCISOCKET
 	bool "Attach Host Bluetooth"

arch/sim/src/Makefile

@@ -111,9 +111,6 @@ ifeq ($(CONFIG_SMP),y)
   CSRCS += up_smpsignal.c up_cpuidlestack.c
   LINKOBJS += up_smpsignal$(OBJEXT)
   HOSTCFLAGS += -DCONFIG_SMP=1 -DCONFIG_SMP_NCPUS=$(CONFIG_SMP_NCPUS)
-ifeq ($(CONFIG_SIM_WALLTIME),y)
-  HOSTCFLAGS += -DCONFIG_SIM_WALLTIME=1
-endif
 ifeq ($(CONFIG_SCHED_INSTRUMENTATION),y)
   HOSTCFLAGS += -DCONFIG_SCHED_INSTRUMENTATION=1
 endif

arch/sim/src/sim/up_simsmp.c

@@ -120,9 +120,7 @@ void sched_note_cpu_resume(struct tcb_s *tcb, int cpu);
 static void *sim_idle_trampoline(void *arg)
 {
   struct sim_cpuinfo_s *cpuinfo = (struct sim_cpuinfo_s *)arg;
-#ifdef CONFIG_SIM_WALLTIME
   uint64_t now = 0;
-#endif
   sigset_t set;
   int ret;
 
@@ -165,16 +163,10 @@ static void *sim_idle_trampoline(void *arg)
 
   for (; ; )
     {
-#ifdef CONFIG_SIM_WALLTIME
       /* Wait a bit so that the timing is close to the correct rate. */
 
       now += 1000 * CONFIG_USEC_PER_TICK;
       host_sleepuntil(now);
-#else
-      /* Give other pthreads/CPUs a shot */
-
-      sched_yield();
-#endif
     }
 
   return NULL;

boards/sim/sim/sim/README.txt

@@ -49,13 +49,7 @@ application that I know of.
 
 Timing Fidelity
 ---------------
-NOTE:  In order to facility fast testing, the sim target's IDLE loop, by
-default, calls the system "interrupt handler" as fast as possible.  As a
-result, there really are no noticeable delays when a task sleeps.  However,
-the task really does sleep -- but the time scale is wrong.  If you want
-behavior that is closer to normal timing, then you can define
-CONFIG_SIM_WALLTIME=y in your configuration file.  This configuration setting
-will cause the sim target's IDLE loop to delay on each call so that the system
+NOTE: The sim target's IDLE loop to delay on each call so that the system
 "timer interrupt" is called at a rate approximately correct for the system
 timer tick rate.  This option can be enabled with CONFIG_SIM_WALLTIME_SIGNAL
 which will drive the entire simulation by using a host timer that ticks at
@@ -317,12 +311,6 @@ SMP
     +CONFIG_SMP_NCPUS=2
     +CONFIG_SMP_IDLETHREAD_STACKSIZE=2048
 
-  You also must enable near-realtime-performance otherwise even long timeouts
-  will expire before a CPU thread even has a chance to execute.
-
-    -# CONFIG_SIM_WALLTIME is not set
-    +CONFIG_SIM_WALLTIME=y
-
   And you can enable some additional debug output with:
 
     -# CONFIG_DEBUG_SCHED is not set