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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2012-12-16 20:00:34 +0100 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2013-01-27 20:35:47 +0100 |
| commit | 6a61671bb2f3a1bd12cd17b8fca811a624782632 (patch) | |
| tree | 0afc2915fb7e517472710a49a524510322dd5baa /include/linux/init_task.h | |
| parent | c11f11fcbdb5be790c565aed46411486a7586afc (diff) | |
| download | lwn-6a61671bb2f3a1bd12cd17b8fca811a624782632.tar.gz lwn-6a61671bb2f3a1bd12cd17b8fca811a624782632.zip | |
cputime: Safely read cputime of full dynticks CPUs
While remotely reading the cputime of a task running in a
full dynticks CPU, the values stored in utime/stime fields
of struct task_struct may be stale. Its values may be those
of the last kernel <-> user transition time snapshot and
we need to add the tickless time spent since this snapshot.
To fix this, flush the cputime of the dynticks CPUs on
kernel <-> user transition and record the time / context
where we did this. Then on top of this snapshot and the current
time, perform the fixup on the reader side from task_times()
accessors.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[fixed kvm module related build errors]
Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Diffstat (limited to 'include/linux/init_task.h')
| -rw-r--r-- | include/linux/init_task.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 6d087c5f57f7..cc898b871cef 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -10,6 +10,7 @@ #include <linux/pid_namespace.h> #include <linux/user_namespace.h> #include <linux/securebits.h> +#include <linux/seqlock.h> #include <net/net_namespace.h> #ifdef CONFIG_SMP @@ -141,6 +142,15 @@ extern struct task_group root_task_group; # define INIT_PERF_EVENTS(tsk) #endif +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN +# define INIT_VTIME(tsk) \ + .vtime_seqlock = __SEQLOCK_UNLOCKED(tsk.vtime_seqlock), \ + .vtime_snap = 0, \ + .vtime_snap_whence = VTIME_SYS, +#else +# define INIT_VTIME(tsk) +#endif + #define INIT_TASK_COMM "swapper" /* @@ -210,6 +220,7 @@ extern struct task_group root_task_group; INIT_TRACE_RECURSION \ INIT_TASK_RCU_PREEMPT(tsk) \ INIT_CPUSET_SEQ \ + INIT_VTIME(tsk) \ } |