> From: Frederic Konrad [mailto:fred.kon...@greensocs.com] > On 07/11/2014 12:36, Pavel Dovgaluk wrote: > >> From: Paolo Bonzini [mailto:pbonz...@redhat.com] > >> On 07/11/2014 11:32, Pavel Dovgalyuk wrote: > >>> Replay uses number of executed instructions to determine corrent events > >>> injection moments. This patch introduces new function for querying the > >>> instructions counter. > >>> > >>> Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru> > >>> --- > >>> cpus.c | 26 +++++++++++++++++++++++--- > >>> include/qemu/timer.h | 1 + > >>> 2 files changed, 24 insertions(+), 3 deletions(-) > >>> > >>> diff --git a/cpus.c b/cpus.c > >>> index 7e8c507..2ec6d75 100644 > >>> --- a/cpus.c > >>> +++ b/cpus.c > >>> @@ -136,8 +136,7 @@ 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_instructions_counter_locked(void) > >>> { > >>> int64_t icount; > >>> CPUState *cpu = current_cpu; > >>> @@ -145,10 +144,31 @@ static int64_t cpu_get_icount_locked(void) > >>> icount = timers_state.qemu_icount; > >>> if (cpu) { > >>> if (!cpu_can_do_io(cpu)) { > >>> - fprintf(stderr, "Bad clock read\n"); > >>> + fprintf(stderr, "Bad icount read\n"); > >>> + exit(1); > >>> } > >>> icount -= (cpu->icount_decr.u16.low + cpu->icount_extra); > >>> } > >>> + return icount; > >>> +} > >>> + > >>> +int64_t cpu_get_instructions_counter(void) > >>> +{ > >>> + /* This function calls are synchnonized to timer changes, > >>> + calling cpu_get_instructions_counter_locked without lock is safe > >>> */ > >>> + int64_t icount = timers_state.qemu_icount; > >>> + CPUState *cpu = current_cpu; > >>> + > >>> + if (cpu) { > >>> + icount -= (cpu->icount_decr.u16.low + cpu->icount_extra); > >>> + } > >>> + return icount; > >>> +} > >> This is the same as Frederic's QEMU_CLOCK_ICOUNT clock, right? Any > >> reason why one is better than the other? > > Not really. Frederic's QEMU_CLOCK_ICOUNT is measured in nanoseconds. > > And this counter is measured in instructions. > > > So you transformed your implementation to use icount?
Right, new implementation uses icount. > I guess you replay event's according to the current instruction? > I implemented icount clock with the QEMUTimer API so a callback can be > notified during the replay at the right instruction. We cannot use timers, because there are synchronization events (like exceptions, interrupts, timer reads) that control the execution correctness. > By the way do you have a git tree somewhere where I can get the patches? No, there is no public repository. There are only the patches in the mail list. Pavel Dovgalyuk