[Qemu-devel] [PATCH 0/2] cpu-exec: simplify -icount align

[Qemu-devel] [PATCH 0/2] cpu-exec: simplify -icount align

[Paolo Bonzini]

Two simplifications to the -icount align code.

Paolo Bonzini (2):
  cpu-exec: simplify align_clocks
  cpu-exec: simplify init_delay_params

 cpu-exec.c           |  9 +++------
 cpus.c               | 17 -----------------
 include/qemu/timer.h |  1 -
 3 files changed, 3 insertions(+), 24 deletions(-)

-- 
2.1.0

[Qemu-devel] [PATCH 1/2] cpu-exec: simplify align_clocks

[Paolo Bonzini]

sc->diff_clk is already equal to sleep_delay (split in a second and a
nanosecond part).  If you subtract sleep_delay - rem_delay, the result
is exactly rem_delay.

Cc: Sebastian Tanase <sebastian.tanase@openwide.fr>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 cpu-exec.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/cpu-exec.c b/cpu-exec.c
index a4f0eff..ef0f12c 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -61,8 +61,7 @@ static void align_clocks(SyncClocks *sc, const CPUState *cpu)
         sleep_delay.tv_sec = sc->diff_clk / 1000000000LL;
         sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL;
         if (nanosleep(&sleep_delay, &rem_delay) < 0) {
-            sc->diff_clk -= (sleep_delay.tv_sec - rem_delay.tv_sec) * 1000000000LL;
-            sc->diff_clk -= sleep_delay.tv_nsec - rem_delay.tv_nsec;
+            sc->diff_clk = rem_delay.tv_sec * 1000000000LL +  rem_delay.tv_nsec;
         } else {
             sc->diff_clk = 0;
         }
-- 
2.1.0

[Qemu-devel] [PATCH 2/2] cpu-exec: simplify init_delay_params

[Paolo Bonzini]

With the introduction of QEMU_CLOCK_VIRTUAL_RT, the computation of
sc->diff_clk can be simplified nicely:

        qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
        qemu_clock_get_ns(QEMU_CLOCK_REALTIME) +
        cpu_get_clock_offset()

     =  qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
        (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - cpu_get_clock_offset())

     =  qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
        (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + timers_state.cpu_clock_offset)

     =  qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
        qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT)

Cc: Sebastian Tanase <sebastian.tanase@openwide.fr>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 cpu-exec.c           |  8 +++-----
 cpus.c               | 17 -----------------
 include/qemu/timer.h |  1 -
 3 files changed, 3 insertions(+), 23 deletions(-)

diff --git a/cpu-exec.c b/cpu-exec.c
index ef0f12c..fa506e6 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -61,7 +61,7 @@ static void align_clocks(SyncClocks *sc, const CPUState *cpu)
         sleep_delay.tv_sec = sc->diff_clk / 1000000000LL;
         sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL;
         if (nanosleep(&sleep_delay, &rem_delay) < 0) {
-            sc->diff_clk = rem_delay.tv_sec * 1000000000LL +  rem_delay.tv_nsec;
+            sc->diff_clk = rem_delay.tv_sec * 1000000000LL + rem_delay.tv_nsec;
         } else {
             sc->diff_clk = 0;
         }
@@ -100,10 +100,8 @@ static void init_delay_params(SyncClocks *sc,
     if (!icount_align_option) {
         return;
     }
-    sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
-    sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
-                   sc->realtime_clock +
-                   cpu_get_clock_offset();
+    sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
+    sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - sc->realtime_clock;
     sc->last_cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low;
     if (sc->diff_clk < max_delay) {
         max_delay = sc->diff_clk;
diff --git a/cpus.c b/cpus.c
index 2edb5cd..b8bd127 100644
--- a/cpus.c
+++ b/cpus.c
@@ -229,23 +229,6 @@ int64_t cpu_get_clock(void)
     return ti;
 }
 
-/* return the offset between the host clock and virtual CPU clock */
-int64_t cpu_get_clock_offset(void)
-{
-    int64_t ti;
-    unsigned start;
-
-    do {
-        start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
-        ti = timers_state.cpu_clock_offset;
-        if (!timers_state.cpu_ticks_enabled) {
-            ti -= get_clock();
-        }
-    } while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
-
-    return -ti;
-}
-
 /* enable cpu_get_ticks()
  * Caller must hold BQL which server as mutex for vm_clock_seqlock.
  */
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index d9df094..ff4e794 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -754,7 +754,6 @@ static inline int64_t get_clock(void)
 int64_t cpu_get_icount_raw(void);
 int64_t cpu_get_icount(void);
 int64_t cpu_get_clock(void);
-int64_t cpu_get_clock_offset(void);
 int64_t cpu_icount_to_ns(int64_t icount);
 
 /*******************************************/
-- 
2.1.0