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authorVenkatesh Pallipadi <venki@google.com>2011-02-10 10:23:27 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2011-02-17 15:37:25 -0800
commit5e7ce6ec134635a572ca0457ed2460dfe70337ea (patch)
tree88228ac32beccd9855575cf3686247e1e3559fb2 /kernel/sched.c
parent9b511401474c4518d214a02a8064b67e038a8e38 (diff)
sched: Add IRQ_TIME_ACCOUNTING, finer accounting of irq time
Commit: b52bfee445d315549d41eacf2fa7c156e7d153d5 upstream s390/powerpc/ia64 have support for CONFIG_VIRT_CPU_ACCOUNTING which does the fine granularity accounting of user, system, hardirq, softirq times. Adding that option on archs like x86 will be challenging however, given the state of TSC reliability on various platforms and also the overhead it will add in syscall entry exit. Instead, add a lighter variant that only does finer accounting of hardirq and softirq times, providing precise irq times (instead of timer tick based samples). This accounting is added with a new config option CONFIG_IRQ_TIME_ACCOUNTING so that there won't be any overhead for users not interested in paying the perf penalty. This accounting is based on sched_clock, with the code being generic. So, other archs may find it useful as well. This patch just adds the core logic and does not enable this logic yet. Signed-off-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286237003-12406-5-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index fc1840961145..fe7082775973 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1807,6 +1807,55 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
#endif
}
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+
+static DEFINE_PER_CPU(u64, cpu_hardirq_time);
+static DEFINE_PER_CPU(u64, cpu_softirq_time);
+
+static DEFINE_PER_CPU(u64, irq_start_time);
+static int sched_clock_irqtime;
+
+void enable_sched_clock_irqtime(void)
+{
+ sched_clock_irqtime = 1;
+}
+
+void disable_sched_clock_irqtime(void)
+{
+ sched_clock_irqtime = 0;
+}
+
+void account_system_vtime(struct task_struct *curr)
+{
+ unsigned long flags;
+ int cpu;
+ u64 now, delta;
+
+ if (!sched_clock_irqtime)
+ return;
+
+ local_irq_save(flags);
+
+ now = sched_clock();
+ cpu = smp_processor_id();
+ delta = now - per_cpu(irq_start_time, cpu);
+ per_cpu(irq_start_time, cpu) = now;
+ /*
+ * We do not account for softirq time from ksoftirqd here.
+ * We want to continue accounting softirq time to ksoftirqd thread
+ * in that case, so as not to confuse scheduler with a special task
+ * that do not consume any time, but still wants to run.
+ */
+ if (hardirq_count())
+ per_cpu(cpu_hardirq_time, cpu) += delta;
+ else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD))
+ per_cpu(cpu_softirq_time, cpu) += delta;
+
+ local_irq_restore(flags);
+}
+
+#endif
+
#include "sched_stats.h"
#include "sched_idletask.c"
#include "sched_fair.c"