path: root/kernel/time/timer_list.c
diff options
authorThomas Gleixner <tglx@linutronix.de>2009-11-13 17:05:44 +0100
committerThomas Gleixner <tglx@linutronix.de>2009-12-10 13:08:11 +0100
commit41d2e494937715d3150e5c75d01f0e75ae899337 (patch)
tree9bc7270aa7b06ed065671a96085fbdf235977d91 /kernel/time/timer_list.c
parent3067e02f8f3ae2f3f02ba76400d03b8bcb4942b0 (diff)
hrtimer: Tune hrtimer_interrupt hang logic
The hrtimer_interrupt hang logic adjusts min_delta_ns based on the execution time of the hrtimer callbacks. This is error-prone for virtual machines, where a guest vcpu can be scheduled out during the execution of the callbacks (and the callbacks themselves can do operations that translate to blocking operations in the hypervisor), which in can lead to large min_delta_ns rendering the system unusable. Replace the current heuristics with something more reliable. Allow the interrupt code to try 3 times to catch up with the lost time. If that fails use the total time spent in the interrupt handler to defer the next timer interrupt so the system can catch up with other things which got delayed. Limit that deferment to 100ms. The retry events and the maximum time spent in the interrupt handler are recorded and exposed via /proc/timer_list Inspired by a patch from Marcelo. Reported-by: Michael Tokarev <mjt@tls.msk.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Marcelo Tosatti <mtosatti@redhat.com> Cc: kvm@vger.kernel.org
Diffstat (limited to 'kernel/time/timer_list.c')
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 665c76edbf1..9d80db4747d 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -150,6 +150,9 @@ static void print_cpu(struct seq_file *m, int cpu, u64 now)
+ P(nr_retries);
+ P(nr_hangs);
+ P_ns(max_hang_time);
#undef P
#undef P_ns
@@ -254,7 +257,7 @@ static int timer_list_show(struct seq_file *m, void *v)
u64 now = ktime_to_ns(ktime_get());
int cpu;
- SEQ_printf(m, "Timer List Version: v0.4\n");
+ SEQ_printf(m, "Timer List Version: v0.5\n");
SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);