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author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-10-05 16:42:36 -0300 |
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committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-10-05 16:43:53 -0300 |
commit | 9fce0c226536fc36c7fb0a80000ca38a995be43e (patch) | |
tree | d1d03d4a831bb143ffd401cefa0f44f636ac0084 /kernel/sched/cputime.c | |
parent | 3cc2691227203c00cac1d82d6b0772224d5c87b2 (diff) | |
parent | c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 (diff) | |
download | linux-9fce0c226536fc36c7fb0a80000ca38a995be43e.tar.bz2 |
Merge tag 'v4.8' into patchwork
Linux 4.8
* tag 'v4.8': (1761 commits)
Linux 4.8
ARM: 8618/1: decompressor: reset ttbcr fields to use TTBR0 on ARMv7
MIPS: CM: Fix mips_cm_max_vp_width for non-MT kernels on MT systems
include/linux/property.h: fix typo/compile error
ocfs2: fix deadlock on mmapped page in ocfs2_write_begin_nolock()
mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()
MAINTAINERS: Switch to kernel.org email address for Javi Merino
x86/entry/64: Fix context tracking state warning when load_gs_index fails
x86/boot: Initialize FPU and X86_FEATURE_ALWAYS even if we don't have CPUID
x86/vdso: Fix building on big endian host
x86/boot: Fix another __read_cr4() case on 486
sctp: fix the issue sctp_diag uses lock_sock in rcu_read_lock
sctp: change to check peer prsctp_capable when using prsctp polices
sctp: remove prsctp_param from sctp_chunk
sctp: move sent_count to the memory hole in sctp_chunk
tg3: Avoid NULL pointer dereference in tg3_io_error_detected()
x86/init: Fix cr4_init_shadow() on CR4-less machines
MIPS: Fix detection of unsupported highmem with cache aliases
MIPS: Malta: Fix IOCU disable switch read for MIPS64
MIPS: Fix BUILD_ROLLBACK_PROLOGUE for microMIPS
...
Diffstat (limited to 'kernel/sched/cputime.c')
-rw-r--r-- | kernel/sched/cputime.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 1934f658c036..a846cf89eb96 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -263,6 +263,11 @@ void account_idle_time(cputime_t cputime) cpustat[CPUTIME_IDLE] += (__force u64) cputime; } +/* + * When a guest is interrupted for a longer amount of time, missed clock + * ticks are not redelivered later. Due to that, this function may on + * occasion account more time than the calling functions think elapsed. + */ static __always_inline cputime_t steal_account_process_time(cputime_t maxtime) { #ifdef CONFIG_PARAVIRT @@ -371,7 +376,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, * idle, or potentially user or system time. Due to rounding, * other time can exceed ticks occasionally. */ - other = account_other_time(cputime); + other = account_other_time(ULONG_MAX); if (other >= cputime) return; cputime -= other; @@ -486,7 +491,7 @@ void account_process_tick(struct task_struct *p, int user_tick) } cputime = cputime_one_jiffy; - steal = steal_account_process_time(cputime); + steal = steal_account_process_time(ULONG_MAX); if (steal >= cputime) return; @@ -508,13 +513,21 @@ void account_process_tick(struct task_struct *p, int user_tick) */ void account_idle_ticks(unsigned long ticks) { + cputime_t cputime, steal; if (sched_clock_irqtime) { irqtime_account_idle_ticks(ticks); return; } - account_idle_time(jiffies_to_cputime(ticks)); + cputime = jiffies_to_cputime(ticks); + steal = steal_account_process_time(ULONG_MAX); + + if (steal >= cputime) + return; + + cputime -= steal; + account_idle_time(cputime); } /* @@ -606,19 +619,25 @@ static void cputime_adjust(struct task_cputime *curr, stime = curr->stime; utime = curr->utime; - if (utime == 0) { - stime = rtime; + /* + * If either stime or both stime and utime are 0, assume all runtime is + * userspace. Once a task gets some ticks, the monotonicy code at + * 'update' will ensure things converge to the observed ratio. + */ + if (stime == 0) { + utime = rtime; goto update; } - if (stime == 0) { - utime = rtime; + if (utime == 0) { + stime = rtime; goto update; } stime = scale_stime((__force u64)stime, (__force u64)rtime, (__force u64)(stime + utime)); +update: /* * Make sure stime doesn't go backwards; this preserves monotonicity * for utime because rtime is monotonic. @@ -641,7 +660,6 @@ static void cputime_adjust(struct task_cputime *curr, stime = rtime - utime; } -update: prev->stime = stime; prev->utime = utime; out: @@ -686,6 +704,13 @@ static cputime_t get_vtime_delta(struct task_struct *tsk) unsigned long now = READ_ONCE(jiffies); cputime_t delta, other; + /* + * Unlike tick based timing, vtime based timing never has lost + * ticks, and no need for steal time accounting to make up for + * lost ticks. Vtime accounts a rounded version of actual + * elapsed time. Limit account_other_time to prevent rounding + * errors from causing elapsed vtime to go negative. + */ delta = jiffies_to_cputime(now - tsk->vtime_snap); other = account_other_time(delta); WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE); |