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Commit e6e6685accfa81f509fadfc9624bc7c3862d75c4

Authored by Glauber Costa
Committed by Avi Kivity
1 parent 747f292583
Exists in master and in 6 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

KVM guest: Steal time accounting 

This patch accounts steal time time in account_process_tick.
If one or more tick is considered stolen in the current
accounting cycle, user/system accounting is skipped. Idle is fine,
since the hypervisor does not report steal time if the guest
is halted.

Accounting steal time from the core scheduler give us the
advantage of direct acess to the runqueue data. In a later
opportunity, it can be used to tweak cpu power and make
the scheduler aware of the time it lost.

[avi: <asm/paravirt.h> doesn't exist on many archs]

Signed-off-by: Glauber Costa <glommer@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Eric B Munson <emunson@mgebm.net>
CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
CC: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

Showing 1 changed file with 43 additions and 0 deletions Side-by-side Diff

... ... @@ -75,6 +75,9 @@
75 75 #include <asm/tlb.h>
76 76 #include <asm/irq_regs.h>
77 77 #include <asm/mutex.h>
  78 +#ifdef CONFIG_PARAVIRT
  79 +#include <asm/paravirt.h>
  80 +#endif
78 81  
79 82 #include "sched_cpupri.h"
80 83 #include "workqueue_sched.h"
... ... @@ -528,6 +531,9 @@
528 531 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
529 532 u64 prev_irq_time;
530 533 #endif
  534 +#ifdef CONFIG_PARAVIRT
  535 + u64 prev_steal_time;
  536 +#endif
531 537  
532 538 /* calc_load related fields */
533 539 unsigned long calc_load_update;
... ... @@ -1953,6 +1959,18 @@
1953 1959 }
1954 1960 EXPORT_SYMBOL_GPL(account_system_vtime);
1955 1961  
  1962 +#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
  1963 +
  1964 +#ifdef CONFIG_PARAVIRT
  1965 +static inline u64 steal_ticks(u64 steal)
  1966 +{
  1967 + if (unlikely(steal > NSEC_PER_SEC))
  1968 + return div_u64(steal, TICK_NSEC);
  1969 +
  1970 + return __iter_div_u64_rem(steal, TICK_NSEC, &steal);
  1971 +}
  1972 +#endif
  1973 +
1956 1974 static void update_rq_clock_task(struct rq *rq, s64 delta)
1957 1975 {
1958 1976 s64 irq_delta;
... ... @@ -3845,6 +3863,25 @@
3845 3863 cpustat->idle = cputime64_add(cpustat->idle, cputime64);
3846 3864 }
3847 3865  
  3866 +static __always_inline bool steal_account_process_tick(void)
  3867 +{
  3868 +#ifdef CONFIG_PARAVIRT
  3869 + if (static_branch(&paravirt_steal_enabled)) {
  3870 + u64 steal, st = 0;
  3871 +
  3872 + steal = paravirt_steal_clock(smp_processor_id());
  3873 + steal -= this_rq()->prev_steal_time;
  3874 +
  3875 + st = steal_ticks(steal);
  3876 + this_rq()->prev_steal_time += st * TICK_NSEC;
  3877 +
  3878 + account_steal_time(st);
  3879 + return st;
  3880 + }
  3881 +#endif
  3882 + return false;
  3883 +}
  3884 +
3848 3885 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
3849 3886  
3850 3887 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
... ... @@ -3876,6 +3913,9 @@
3876 3913 cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
3877 3914 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3878 3915  
  3916 + if (steal_account_process_tick())
  3917 + return;
  3918 +
3879 3919 if (irqtime_account_hi_update()) {
3880 3920 cpustat->irq = cputime64_add(cpustat->irq, tmp);
3881 3921 } else if (irqtime_account_si_update()) {
... ... @@ -3928,6 +3968,9 @@
3928 3968 irqtime_account_process_tick(p, user_tick, rq);
3929 3969 return;
3930 3970 }
  3971 +
  3972 + if (steal_account_process_tick())
  3973 + return;
3931 3974  
3932 3975 if (user_tick)
3933 3976 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);