This patch accounts steal time time in kernel/sched. I kept it from last proposal, because I still see advantages in it: Doing it here will give us easier access from scheduler variables such as the cpu rq. The next patch shows an example of usage for it.
Since functions like account_idle_time() can be called from multiple places, not only account_process_tick(), steal time grabbing is repeated in each account function separatedely. Signed-off-by: Glauber Costa <[email protected]> CC: Rik van Riel <[email protected]> CC: Jeremy Fitzhardinge <[email protected]> CC: Peter Zijlstra <[email protected]> CC: Avi Kivity <[email protected]> CC: Anthony Liguori <[email protected]> CC: Eric B Munson <[email protected]> --- kernel/sched.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 52 insertions(+), 0 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 3f2e502..c166863 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -75,6 +75,7 @@ #include <asm/tlb.h> #include <asm/irq_regs.h> #include <asm/mutex.h> +#include <asm/paravirt.h> #include "sched_cpupri.h" #include "workqueue_sched.h" @@ -528,6 +529,7 @@ struct rq { #ifdef CONFIG_IRQ_TIME_ACCOUNTING u64 prev_irq_time; #endif + u64 prev_steal_time; /* calc_load related fields */ unsigned long calc_load_update; @@ -1953,6 +1955,48 @@ void account_system_vtime(struct task_struct *curr) } EXPORT_SYMBOL_GPL(account_system_vtime); +#endif /* CONFIG_IRQ_TIME_ACCOUNTING */ + +static inline u64 steal_ticks(u64 steal) +{ + if (unlikely(steal > NSEC_PER_SEC)) + return steal / TICK_NSEC; + + return __iter_div_u64_rem(steal, TICK_NSEC, &steal); +} + +/* + * We have to at flush steal time information every time something else + * is accounted. Since the accounting functions are all visible to the rest + * of the kernel, it gets tricky to do them in one place. This helper function + * helps us. + * + * When the system is idle, the concept of steal time does not apply. We just + * tell the underlying hypervisor that we grabbed the data, but skip steal time + * accounting + */ +static noinline bool touch_steal_time(int is_idle) +{ + u64 steal, st = 0; + + if (static_branch(¶virt_steal_enabled)) { + + steal = paravirt_steal_clock(smp_processor_id()); + + steal -= this_rq()->prev_steal_time; + + st = steal_ticks(steal); + this_rq()->prev_steal_time += st * TICK_NSEC; + + if (is_idle || st == 0) + return false; + + account_steal_time(st); + return true; + } + return false; +} + static void update_rq_clock_task(struct rq *rq, s64 delta) { s64 irq_delta; @@ -3716,6 +3760,9 @@ void account_user_time(struct task_struct *p, cputime_t cputime, struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t tmp; + if (touch_steal_time(0)) + return; + /* Add user time to process. */ p->utime = cputime_add(p->utime, cputime); p->utimescaled = cputime_add(p->utimescaled, cputime_scaled); @@ -3802,6 +3849,9 @@ void account_system_time(struct task_struct *p, int hardirq_offset, struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t *target_cputime64; + if (touch_steal_time(0)) + return; + if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { account_guest_time(p, cputime, cputime_scaled); return; @@ -3839,6 +3889,8 @@ void account_idle_time(cputime_t cputime) cputime64_t cputime64 = cputime_to_cputime64(cputime); struct rq *rq = this_rq(); + touch_steal_time(1); + if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, cputime64); else -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
