diff options
author | Paul Mackerras <paulus@samba.org> | 2009-02-09 06:42:47 -0500 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2009-02-09 06:47:16 -0500 |
commit | 23a185ca8abbeef64b6ffc33059b1d630e43ec10 (patch) | |
tree | c5eb9454ff969377adb40532119240f6fc893fcb /include/linux | |
parent | 82aa9a1829199233f9bdaf26e2ee271114f4701e (diff) |
perf_counters: make software counters work as per-cpu counters
Impact: kernel crash fix
Yanmin Zhang reported that using a PERF_COUNT_TASK_CLOCK software
counter as a per-cpu counter would reliably crash the system, because
it calls __task_delta_exec with a null pointer. The page fault,
context switch and cpu migration counters also won't function
correctly as per-cpu counters since they reference the current task.
This fixes the problem by redirecting the task_clock counter to the
cpu_clock counter when used as a per-cpu counter, and by implementing
per-cpu page fault, context switch and cpu migration counters.
Along the way, this:
- Initializes counter->ctx earlier, in perf_counter_alloc, so that
sw_perf_counter_init can use it
- Adds code to kernel/sched.c to count task migrations into each
cpu, in rq->nr_migrations_in
- Exports the per-cpu context switch and task migration counts
via new functions added to kernel/sched.c
- Makes sure that if sw_perf_counter_init fails, we don't try to
initialize the counter as a hardware counter. Since the user has
passed a negative, non-raw event type, they clearly don't intend
for it to be interpreted as a hardware event.
Reported-by: "Zhang Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/sched.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index b85b10abf770..1e5f70062a9c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h | |||
@@ -137,6 +137,8 @@ extern unsigned long nr_running(void); | |||
137 | extern unsigned long nr_uninterruptible(void); | 137 | extern unsigned long nr_uninterruptible(void); |
138 | extern unsigned long nr_active(void); | 138 | extern unsigned long nr_active(void); |
139 | extern unsigned long nr_iowait(void); | 139 | extern unsigned long nr_iowait(void); |
140 | extern u64 cpu_nr_switches(int cpu); | ||
141 | extern u64 cpu_nr_migrations(int cpu); | ||
140 | 142 | ||
141 | struct seq_file; | 143 | struct seq_file; |
142 | struct cfs_rq; | 144 | struct cfs_rq; |