[Qemu-devel] [PATCH 14/19] disentangle tcg and deadline calculation

[Paolo Bonzini]

Just tell main_loop_wait whether to be blocking or nonblocking, so that
there is no need to call qemu_cpus_have_work from the timer subsystem.
Instead, tcg_cpu_exec can say "we want the main loop not to block because
we have stuff to do".

Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
 hw/xenfb.c |    6 ++++--
 sysemu.h   |    2 +-
 vl.c       |   25 ++++++++++++++++---------
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/hw/xenfb.c b/hw/xenfb.c
index 795a326..422cd53 100644
--- a/hw/xenfb.c
+++ b/hw/xenfb.c
@@ -983,12 +983,14 @@ void xen_init_display(int domid)
 
 wait_more:
     i++;
-    main_loop_wait(10); /* miliseconds */
+    main_loop_wait(true);
     xfb = xen_be_find_xendev("vfb", domid, 0);
     xin = xen_be_find_xendev("vkbd", domid, 0);
     if (!xfb || !xin) {
-        if (i < 256)
+        if (i < 256) {
+            usleep(10000);
             goto wait_more;
+        }
         xen_be_printf(NULL, 1, "displaystate setup failed\n");
         return;
     }
diff --git a/sysemu.h b/sysemu.h
index 9d80bb2..1384ef9 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -60,7 +60,7 @@ void do_info_snapshots(Monitor *mon);
 
 void qemu_announce_self(void);
 
-void main_loop_wait(int timeout);
+void main_loop_wait(bool nonblocking);
 
 int qemu_savevm_state_begin(Monitor *mon, QEMUFile *f, int blk_enable,
                             int shared);
diff --git a/vl.c b/vl.c
index 9bf9806..f7472db 100644
--- a/vl.c
+++ b/vl.c
@@ -592,6 +592,7 @@ struct qemu_alarm_timer {
 };
 
 static struct qemu_alarm_timer *alarm_timer;
+static int qemu_calculate_timeout(void);
 
 static inline int qemu_alarm_pending(void)
 {
@@ -3507,7 +3508,7 @@ static void *kvm_cpu_thread_fn(void *arg)
     return NULL;
 }
 
-static void tcg_cpu_exec(void);
+static bool tcg_cpu_exec(void);
 
 static void *tcg_cpu_thread_fn(void *arg)
 {
@@ -3786,14 +3787,20 @@ static void host_main_loop_wait(int *timeout)
 }
 #endif
 
-void main_loop_wait(int timeout)
+void main_loop_wait(bool nonblocking)
 {
     IOHandlerRecord *ioh;
     fd_set rfds, wfds, xfds;
     int ret, nfds;
     struct timeval tv;
+    int timeout;
 
-    qemu_bh_update_timeout(&timeout);
+    if (nonblocking)
+        timeout = 0;
+    else {
+        timeout = qemu_calculate_timeout();
+        qemu_bh_update_timeout(&timeout);
+    }
 
     host_main_loop_wait(&timeout);
 
@@ -3898,7 +3905,7 @@ static int qemu_cpu_exec(CPUState *env)
     return ret;
 }
 
-static void tcg_cpu_exec(void)
+static bool tcg_cpu_exec(void)
 {
     int ret = 0;
 
@@ -3908,7 +3915,7 @@ static void tcg_cpu_exec(void)
         CPUState *env = cur_cpu = next_cpu;
 
         if (!vm_running)
-            break;
+            return false;
         if (qemu_alarm_pending())
             break;
         if (cpu_can_run(env))
@@ -3919,6 +3926,7 @@ static void tcg_cpu_exec(void)
             break;
         }
     }
+    return qemu_cpus_have_work();
 }
 
 static int qemu_calculate_timeout(void)
@@ -3928,8 +3936,6 @@ static int qemu_calculate_timeout(void)
 
     if (!vm_running)
         timeout = 5000;
-    else if (qemu_cpus_have_work())
-        timeout = 0;
     else {
      /* XXX: use timeout computed from timers */
         int64_t add;
@@ -3989,16 +3995,17 @@ static void main_loop(void)
 
     for (;;) {
         do {
+            bool nonblocking = false;
 #ifdef CONFIG_PROFILER
             int64_t ti;
 #endif
 #ifndef CONFIG_IOTHREAD
-            tcg_cpu_exec();
+            nonblocking = tcg_cpu_exec();
 #endif
 #ifdef CONFIG_PROFILER
             ti = profile_getclock();
 #endif
-            main_loop_wait(qemu_calculate_timeout());
+            main_loop_wait(nonblocking);
 #ifdef CONFIG_PROFILER
             dev_time += profile_getclock() - ti;
 #endif
-- 
1.6.5.2