From 09000adb86550d2895b64faa52e64eaec3cae7b2 Mon Sep 17 00:00:00 2001 From: Bharat Bhushan Date: Fri, 25 Mar 2011 10:32:13 +0530 Subject: KVM: PPC: Fix issue clearing exit timing counters Following dump is observed on host when clearing the exit timing counters [root@p1021mds kvm]# echo -n 'c' > vm1200_vcpu0_timing INFO: task echo:1276 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. echo D 0ff5bf94 0 1276 1190 0x00000000 Call Trace: [c2157e40] [c0007908] __switch_to+0x9c/0xc4 [c2157e50] [c040293c] schedule+0x1b4/0x3bc [c2157e90] [c04032dc] __mutex_lock_slowpath+0x74/0xc0 [c2157ec0] [c00369e4] kvmppc_init_timing_stats+0x20/0xb8 [c2157ed0] [c0036b00] kvmppc_exit_timing_write+0x84/0x98 [c2157ef0] [c00b9f90] vfs_write+0xc0/0x16c [c2157f10] [c00ba284] sys_write+0x4c/0x90 [c2157f40] [c000e320] ret_from_syscall+0x0/0x3c The vcpu->mutex is used by kvm_ioctl_* (KVM_RUN etc) and same was used when clearing the stats (in kvmppc_init_timing_stats()). What happens is that when the guest is idle then it held the vcpu->mutx. While the exiting timing process waits for guest to release the vcpu->mutex and a hang state is reached. Now using seprate lock for exit timing stats. Signed-off-by: Bharat Bhushan Acked-by: Alexander Graf Signed-off-by: Avi Kivity --- arch/powerpc/kvm/timing.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'arch/powerpc/kvm/timing.c') diff --git a/arch/powerpc/kvm/timing.c b/arch/powerpc/kvm/timing.c index a021f5827a33..18f40fd3e98f 100644 --- a/arch/powerpc/kvm/timing.c +++ b/arch/powerpc/kvm/timing.c @@ -34,8 +34,8 @@ void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu) { int i; - /* pause guest execution to avoid concurrent updates */ - mutex_lock(&vcpu->mutex); + /* Take a lock to avoid concurrent updates */ + mutex_lock(&vcpu->arch.exit_timing_lock); vcpu->arch.last_exit_type = 0xDEAD; for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) { @@ -49,7 +49,7 @@ void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu) vcpu->arch.timing_exit.tv64 = 0; vcpu->arch.timing_last_enter.tv64 = 0; - mutex_unlock(&vcpu->mutex); + mutex_unlock(&vcpu->arch.exit_timing_lock); } static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type) @@ -65,6 +65,8 @@ static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type) return; } + mutex_lock(&vcpu->arch.exit_timing_lock); + vcpu->arch.timing_count_type[type]++; /* sum */ @@ -93,6 +95,8 @@ static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type) vcpu->arch.timing_min_duration[type] = duration; if (unlikely(duration > vcpu->arch.timing_max_duration[type])) vcpu->arch.timing_max_duration[type] = duration; + + mutex_unlock(&vcpu->arch.exit_timing_lock); } void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu) -- cgit v1.2.2 From 1a040b26c5c915b317103b87ae7006d40443f197 Mon Sep 17 00:00:00 2001 From: Stuart Yoder Date: Mon, 28 Mar 2011 15:01:56 -0500 Subject: KVM: PPC: use ticks, not usecs, for exit timing Convert to microseconds when displaying (with fix from Bharat Bhushan ). This reduces rounding error with large quantities of short exits. Signed-off-by: Stuart Yoder Signed-off-by: Scott Wood Signed-off-by: Alexander Graf --- arch/powerpc/kvm/timing.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'arch/powerpc/kvm/timing.c') diff --git a/arch/powerpc/kvm/timing.c b/arch/powerpc/kvm/timing.c index 18f40fd3e98f..319177df9587 100644 --- a/arch/powerpc/kvm/timing.c +++ b/arch/powerpc/kvm/timing.c @@ -151,17 +151,30 @@ static int kvmppc_exit_timing_show(struct seq_file *m, void *private) { struct kvm_vcpu *vcpu = m->private; int i; + u64 min, max, sum, sum_quad; seq_printf(m, "%s", "type count min max sum sum_squared\n"); + for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) { + + min = vcpu->arch.timing_min_duration[i]; + do_div(min, tb_ticks_per_usec); + max = vcpu->arch.timing_max_duration[i]; + do_div(max, tb_ticks_per_usec); + sum = vcpu->arch.timing_sum_duration[i]; + do_div(sum, tb_ticks_per_usec); + sum_quad = vcpu->arch.timing_sum_quad_duration[i]; + do_div(sum_quad, tb_ticks_per_usec); + seq_printf(m, "%12s %10d %10lld %10lld %20lld %20lld\n", kvm_exit_names[i], vcpu->arch.timing_count_type[i], - vcpu->arch.timing_min_duration[i], - vcpu->arch.timing_max_duration[i], - vcpu->arch.timing_sum_duration[i], - vcpu->arch.timing_sum_quad_duration[i]); + min, + max, + sum, + sum_quad); + } return 0; } -- cgit v1.2.2