Commit 62bea5bf authored by Paolo Bonzini's avatar Paolo Bonzini

KVM: add halt_attempted_poll to VCPU stats

This new statistic can help diagnosing VCPUs that, for any reason,
trigger bad behavior of halt_poll_ns autotuning.

For example, say halt_poll_ns = 480000, and wakeups are spaced exactly
like 479us, 481us, 479us, 481us. Then KVM always fails polling and wastes
10+20+40+80+160+320+480 = 1110 microseconds out of every
479+481+479+481+479+481+479 = 3359 microseconds. The VCPU then
is consuming about 30% more CPU than it would use without
polling.  This would show as an abnormally high number of
attempted polling compared to the successful polls.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com<
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8f4216c7
...@@ -148,6 +148,7 @@ struct kvm_vm_stat { ...@@ -148,6 +148,7 @@ struct kvm_vm_stat {
struct kvm_vcpu_stat { struct kvm_vcpu_stat {
u32 halt_successful_poll; u32 halt_successful_poll;
u32 halt_attempted_poll;
u32 halt_wakeup; u32 halt_wakeup;
}; };
......
...@@ -195,6 +195,7 @@ struct kvm_vm_stat { ...@@ -195,6 +195,7 @@ struct kvm_vm_stat {
struct kvm_vcpu_stat { struct kvm_vcpu_stat {
u32 halt_successful_poll; u32 halt_successful_poll;
u32 halt_attempted_poll;
u32 halt_wakeup; u32 halt_wakeup;
}; };
......
...@@ -128,6 +128,7 @@ struct kvm_vcpu_stat { ...@@ -128,6 +128,7 @@ struct kvm_vcpu_stat {
u32 msa_disabled_exits; u32 msa_disabled_exits;
u32 flush_dcache_exits; u32 flush_dcache_exits;
u32 halt_successful_poll; u32 halt_successful_poll;
u32 halt_attempted_poll;
u32 halt_wakeup; u32 halt_wakeup;
}; };
......
...@@ -55,6 +55,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { ...@@ -55,6 +55,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "msa_disabled", VCPU_STAT(msa_disabled_exits), KVM_STAT_VCPU }, { "msa_disabled", VCPU_STAT(msa_disabled_exits), KVM_STAT_VCPU },
{ "flush_dcache", VCPU_STAT(flush_dcache_exits), KVM_STAT_VCPU }, { "flush_dcache", VCPU_STAT(flush_dcache_exits), KVM_STAT_VCPU },
{ "halt_successful_poll", VCPU_STAT(halt_successful_poll), KVM_STAT_VCPU }, { "halt_successful_poll", VCPU_STAT(halt_successful_poll), KVM_STAT_VCPU },
{ "halt_attempted_poll", VCPU_STAT(halt_attempted_poll), KVM_STAT_VCPU },
{ "halt_wakeup", VCPU_STAT(halt_wakeup), KVM_STAT_VCPU }, { "halt_wakeup", VCPU_STAT(halt_wakeup), KVM_STAT_VCPU },
{NULL} {NULL}
}; };
......
...@@ -108,6 +108,7 @@ struct kvm_vcpu_stat { ...@@ -108,6 +108,7 @@ struct kvm_vcpu_stat {
u32 dec_exits; u32 dec_exits;
u32 ext_intr_exits; u32 ext_intr_exits;
u32 halt_successful_poll; u32 halt_successful_poll;
u32 halt_attempted_poll;
u32 halt_wakeup; u32 halt_wakeup;
u32 dbell_exits; u32 dbell_exits;
u32 gdbell_exits; u32 gdbell_exits;
......
...@@ -53,6 +53,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { ...@@ -53,6 +53,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "ext_intr", VCPU_STAT(ext_intr_exits) }, { "ext_intr", VCPU_STAT(ext_intr_exits) },
{ "queue_intr", VCPU_STAT(queue_intr) }, { "queue_intr", VCPU_STAT(queue_intr) },
{ "halt_successful_poll", VCPU_STAT(halt_successful_poll), }, { "halt_successful_poll", VCPU_STAT(halt_successful_poll), },
{ "halt_attempted_poll", VCPU_STAT(halt_attempted_poll), },
{ "halt_wakeup", VCPU_STAT(halt_wakeup) }, { "halt_wakeup", VCPU_STAT(halt_wakeup) },
{ "pf_storage", VCPU_STAT(pf_storage) }, { "pf_storage", VCPU_STAT(pf_storage) },
{ "sp_storage", VCPU_STAT(sp_storage) }, { "sp_storage", VCPU_STAT(sp_storage) },
......
...@@ -63,6 +63,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { ...@@ -63,6 +63,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "dec", VCPU_STAT(dec_exits) }, { "dec", VCPU_STAT(dec_exits) },
{ "ext_intr", VCPU_STAT(ext_intr_exits) }, { "ext_intr", VCPU_STAT(ext_intr_exits) },
{ "halt_successful_poll", VCPU_STAT(halt_successful_poll) }, { "halt_successful_poll", VCPU_STAT(halt_successful_poll) },
{ "halt_attempted_poll", VCPU_STAT(halt_attempted_poll) },
{ "halt_wakeup", VCPU_STAT(halt_wakeup) }, { "halt_wakeup", VCPU_STAT(halt_wakeup) },
{ "doorbell", VCPU_STAT(dbell_exits) }, { "doorbell", VCPU_STAT(dbell_exits) },
{ "guest doorbell", VCPU_STAT(gdbell_exits) }, { "guest doorbell", VCPU_STAT(gdbell_exits) },
......
...@@ -210,6 +210,7 @@ struct kvm_vcpu_stat { ...@@ -210,6 +210,7 @@ struct kvm_vcpu_stat {
u32 exit_validity; u32 exit_validity;
u32 exit_instruction; u32 exit_instruction;
u32 halt_successful_poll; u32 halt_successful_poll;
u32 halt_attempted_poll;
u32 halt_wakeup; u32 halt_wakeup;
u32 instruction_lctl; u32 instruction_lctl;
u32 instruction_lctlg; u32 instruction_lctlg;
......
...@@ -63,6 +63,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { ...@@ -63,6 +63,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "exit_program_interruption", VCPU_STAT(exit_program_interruption) }, { "exit_program_interruption", VCPU_STAT(exit_program_interruption) },
{ "exit_instr_and_program_int", VCPU_STAT(exit_instr_and_program) }, { "exit_instr_and_program_int", VCPU_STAT(exit_instr_and_program) },
{ "halt_successful_poll", VCPU_STAT(halt_successful_poll) }, { "halt_successful_poll", VCPU_STAT(halt_successful_poll) },
{ "halt_attempted_poll", VCPU_STAT(halt_attempted_poll) },
{ "halt_wakeup", VCPU_STAT(halt_wakeup) }, { "halt_wakeup", VCPU_STAT(halt_wakeup) },
{ "instruction_lctlg", VCPU_STAT(instruction_lctlg) }, { "instruction_lctlg", VCPU_STAT(instruction_lctlg) },
{ "instruction_lctl", VCPU_STAT(instruction_lctl) }, { "instruction_lctl", VCPU_STAT(instruction_lctl) },
......
...@@ -711,6 +711,7 @@ struct kvm_vcpu_stat { ...@@ -711,6 +711,7 @@ struct kvm_vcpu_stat {
u32 nmi_window_exits; u32 nmi_window_exits;
u32 halt_exits; u32 halt_exits;
u32 halt_successful_poll; u32 halt_successful_poll;
u32 halt_attempted_poll;
u32 halt_wakeup; u32 halt_wakeup;
u32 request_irq_exits; u32 request_irq_exits;
u32 irq_exits; u32 irq_exits;
......
...@@ -149,6 +149,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { ...@@ -149,6 +149,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "nmi_window", VCPU_STAT(nmi_window_exits) }, { "nmi_window", VCPU_STAT(nmi_window_exits) },
{ "halt_exits", VCPU_STAT(halt_exits) }, { "halt_exits", VCPU_STAT(halt_exits) },
{ "halt_successful_poll", VCPU_STAT(halt_successful_poll) }, { "halt_successful_poll", VCPU_STAT(halt_successful_poll) },
{ "halt_attempted_poll", VCPU_STAT(halt_attempted_poll) },
{ "halt_wakeup", VCPU_STAT(halt_wakeup) }, { "halt_wakeup", VCPU_STAT(halt_wakeup) },
{ "hypercalls", VCPU_STAT(hypercalls) }, { "hypercalls", VCPU_STAT(hypercalls) },
{ "request_irq", VCPU_STAT(request_irq_exits) }, { "request_irq", VCPU_STAT(request_irq_exits) },
......
...@@ -2004,6 +2004,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) ...@@ -2004,6 +2004,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
if (vcpu->halt_poll_ns) { if (vcpu->halt_poll_ns) {
ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns); ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns);
++vcpu->stat.halt_attempted_poll;
do { do {
/* /*
* This sets KVM_REQ_UNHALT if an interrupt * This sets KVM_REQ_UNHALT if an interrupt
......
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