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[Qemu-devel] [RFC PATCH 04/12] icount: introduce icount timer.
From: |
fred . konrad |
Subject: |
[Qemu-devel] [RFC PATCH 04/12] icount: introduce icount timer. |
Date: |
Fri, 21 Mar 2014 20:17:26 +0100 |
From: KONRAD Frederic <address@hidden>
This introduces a new timer based only on instruction counter and without any
compensation.
Signed-off-by: KONRAD Frederic <address@hidden>
---
cpus.c | 28 +++++++++++++++++++++++-----
include/qemu/timer.h | 8 ++++++++
qemu-timer.c | 6 ++++++
stubs/cpu-get-icount.c | 5 +++++
4 files changed, 42 insertions(+), 5 deletions(-)
diff --git a/cpus.c b/cpus.c
index bdbc431..ba096a3 100644
--- a/cpus.c
+++ b/cpus.c
@@ -132,7 +132,7 @@ typedef struct TimersState {
static TimersState timers_state;
/* Return the virtual CPU time, based on the instruction counter. */
-static int64_t cpu_get_icount_locked(void)
+static int64_t cpu_get_icount_locked(int with_bias)
{
int64_t icount;
CPUState *cpu = current_cpu;
@@ -144,7 +144,12 @@ static int64_t cpu_get_icount_locked(void)
}
icount -= (cpu->icount_decr.u16.low + cpu->icount_extra);
}
- return timers_state.qemu_icount_bias + (icount << icount_time_shift);
+
+ if (with_bias) {
+ return timers_state.qemu_icount_bias + (icount << icount_time_shift);
+ } else {
+ return icount << icount_time_shift;
+ }
}
int64_t cpu_get_icount(void)
@@ -154,7 +159,20 @@ int64_t cpu_get_icount(void)
do {
start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
- icount = cpu_get_icount_locked();
+ icount = cpu_get_icount_locked(true);
+ } while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
+
+ return icount;
+}
+
+int64_t cpu_get_icount_wo_bias(void)
+{
+ int64_t icount;
+ unsigned start;
+
+ do {
+ start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
+ icount = cpu_get_icount_locked(false);
} while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
return icount;
@@ -265,7 +283,7 @@ static void icount_adjust(void)
seqlock_write_lock(&timers_state.vm_clock_seqlock);
cur_time = cpu_get_clock_locked();
- cur_icount = cpu_get_icount_locked();
+ cur_icount = cpu_get_icount_locked(true);
delta = cur_icount - cur_time;
/* FIXME: This is a very crude algorithm, somewhat prone to oscillation.
*/
@@ -328,7 +346,7 @@ static void icount_warp_rt(void *opaque)
* far ahead of real time.
*/
int64_t cur_time = cpu_get_clock_locked();
- int64_t cur_icount = cpu_get_icount_locked();
+ int64_t cur_icount = cpu_get_icount_locked(true);
int64_t delta = cur_time - cur_icount;
warp_delta = MIN(warp_delta, delta);
}
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 7f9a074..da47194 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -36,12 +36,19 @@
* is suspended, and it will reflect system time changes the host may
* undergo (e.g. due to NTP). The host clock has the same precision as
* the virtual clock.
+ *
+ * @QEMU_CLOCK_ICOUNT: icount clock
+ *
+ * The icount clock is based on instruction counter without any compensation
for
+ * speed. It will run only when instruction are executed and make only sense in
+ * icount mode.
*/
typedef enum {
QEMU_CLOCK_REALTIME = 0,
QEMU_CLOCK_VIRTUAL = 1,
QEMU_CLOCK_HOST = 2,
+ QEMU_CLOCK_ICOUNT = 3,
QEMU_CLOCK_MAX
} QEMUClockType;
@@ -743,6 +750,7 @@ static inline int64_t get_clock(void)
#endif
/* icount */
+int64_t cpu_get_icount_wo_bias(void);
int64_t cpu_get_icount(void);
int64_t cpu_get_clock(void);
diff --git a/qemu-timer.c b/qemu-timer.c
index e15ce47..8a36906 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -563,6 +563,12 @@ int64_t qemu_clock_get_ns(QEMUClockType type)
notifier_list_notify(&clock->reset_notifiers, &now);
}
return now;
+ case QEMU_CLOCK_ICOUNT:
+ if (use_icount) {
+ return cpu_get_icount_wo_bias();
+ } else {
+ return -1;
+ }
}
}
diff --git a/stubs/cpu-get-icount.c b/stubs/cpu-get-icount.c
index d685859..fa242f3 100644
--- a/stubs/cpu-get-icount.c
+++ b/stubs/cpu-get-icount.c
@@ -7,3 +7,8 @@ int64_t cpu_get_icount(void)
{
abort();
}
+
+int64_t cpu_get_icount_wo_bias(void)
+{
+ abort();
+}
--
1.8.1.4
- Re: [Qemu-devel] [RFC PATCH 03/12] migration: make qemu_savevm_state public., (continued)
[Qemu-devel] [RFC PATCH 07/12] timer: add cpu_icount_to_ns function., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 02/12] migration: migrate icount fields., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 11/12] cexe: synchronize icount on the next event., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 04/12] icount: introduce icount timer.,
fred . konrad <=
[Qemu-devel] [RFC PATCH 05/12] icount: check for icount clock deadline when cpu loop exits., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 08/12] introduce reverse execution mechanism., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 09/12] gdbstub: allow reverse execution in gdb stub., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 12/12] cexe: allow to enable reverse execution., fred . konrad, 2014/03/21
[Qemu-devel] [RFC PATCH 10/12] cpu-exec: trigger a debug request when rexec stops., fred . konrad, 2014/03/21