diff options
authorSebastian Tanase <sebastian.tanase@openwide.fr>2014-07-23 11:47:50 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2014-08-06 17:53:07 +0200
commit714683950547ea8173aefe25f574874c06233455 (patch)
parent3f03131390a8c91a0cac530f7ae79b04b42ab928 (diff)
icount: Fix virtual clock start value on ARM
When using the icount option on ARM, the virtual clock starts counting at realtime clock but it should start at 0. The reason why the virtual clock starts at realtime clock is because the first time we call qemu_clock_warp (which calls icount_warp_rt) in tcg_exec_all, qemu_icount_bias (which is part of the virtual time computation mechanism) will increment by realtime - vm_clock_warp_start, with vm_clock_warp_start being 0 (see icount_warp_rt in cpus.c). By changing the value of vm_clock_warp_start from 0 to -1, the first time we call qemu_clock_warp which calls icount_warp_rt, we will return immediatly because icount_warp_rt first checks if vm_clock_warp_start is -1 and if it's the case it returns. Therefore, qemu_icount_bias will first be incremented by the value of a virtual timer deadline when the virtual cpu goes from active to inactive. The virtual time will start at 0 and increment based on the instruction counter when the vcpu is active or the qemu_icount_bias value when inactive. Signed-off-by: Sebastian Tanase <sebastian.tanase@openwide.fr> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 files changed, 1 insertions, 1 deletions
diff --git a/cpus.c b/cpus.c
index 62636a65a8..bbb8d4e8be 100644
--- a/cpus.c
+++ b/cpus.c
@@ -102,7 +102,7 @@ static bool all_cpu_threads_idle(void)
/* Protected by TimersState seqlock */
-static int64_t vm_clock_warp_start;
+static int64_t vm_clock_warp_start = -1;
/* Conversion factor from emulated instructions to virtual clock ticks. */
static int icount_time_shift;
/* Arbitrarily pick 1MIPS as the minimum allowable speed. */