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perf_counter: Rename perf_counter_limit sysctl

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Rename perf_counter_limit to perf_counter_max_sample_rate and
prohibit creation of counters with a known higher sample
frequency.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-06-11 11:25:05 +02:00 committed by Ingo Molnar
parent 0764771dab
commit df58ab24bf
3 changed files with 23 additions and 12 deletions
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2
include/linux/perf_counter.h
View file

@ -650,7 +650,7 @@ extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
extern int sysctl_perf_counter_paranoid;
extern int sysctl_perf_counter_mlock;
extern int sysctl_perf_counter_limit;
extern int sysctl_perf_counter_sample_rate;
extern void perf_counter_init(void);

27
kernel/perf_counter.c
View file

@ -44,11 +44,12 @@ static atomic_t nr_mmap_counters __read_mostly;
static atomic_t nr_comm_counters __read_mostly;
/*
* 0 - not paranoid
* 1 - disallow cpu counters to unpriv
* 2 - disallow kernel profiling to unpriv
* perf counter paranoia level:
* 0 - not paranoid
* 1 - disallow cpu counters to unpriv
* 2 - disallow kernel profiling to unpriv
*/
int sysctl_perf_counter_paranoid __read_mostly; /* do we need to be privileged */
int sysctl_perf_counter_paranoid __read_mostly;
static inline bool perf_paranoid_cpu(void)
{
@ -61,7 +62,11 @@ static inline bool perf_paranoid_kernel(void)
}
int sysctl_perf_counter_mlock __read_mostly = 512; /* 'free' kb per user */
int sysctl_perf_counter_limit __read_mostly = 100000; /* max NMIs per second */
/*
* max perf counter sample rate
*/
int sysctl_perf_counter_sample_rate __read_mostly = 100000;
static atomic64_t perf_counter_id;
@ -1244,7 +1249,7 @@ static void perf_ctx_adjust_freq(struct perf_counter_context *ctx)
if (interrupts == MAX_INTERRUPTS) {
perf_log_throttle(counter, 1);
counter->pmu->unthrottle(counter);
interrupts = 2*sysctl_perf_counter_limit/HZ;
interrupts = 2*sysctl_perf_counter_sample_rate/HZ;
}
if (!counter->attr.freq || !counter->attr.sample_freq)
@ -1682,7 +1687,7 @@ static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)
spin_lock_irq(&ctx->lock);
if (counter->attr.freq) {
if (value > sysctl_perf_counter_limit) {
if (value > sysctl_perf_counter_sample_rate) {
ret = -EINVAL;
goto unlock;
}
@ -2979,7 +2984,8 @@ int perf_counter_overflow(struct perf_counter *counter, int nmi,
} else {
if (hwc->interrupts != MAX_INTERRUPTS) {
hwc->interrupts++;
if (HZ * hwc->interrupts > (u64)sysctl_perf_counter_limit) {
if (HZ * hwc->interrupts >
(u64)sysctl_perf_counter_sample_rate) {
hwc->interrupts = MAX_INTERRUPTS;
perf_log_throttle(counter, 0);
ret = 1;
@ -3639,6 +3645,11 @@ SYSCALL_DEFINE5(perf_counter_open,
return -EACCES;
}
if (attr.freq) {
if (attr.sample_freq > sysctl_perf_counter_sample_rate)
return -EINVAL;
}
/*
* Get the target context (task or percpu):
*/

6
kernel/sysctl.c
View file

@ -932,9 +932,9 @@ static struct ctl_table kern_table[] = {
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "perf_counter_int_limit",
.data = &sysctl_perf_counter_limit,
.maxlen = sizeof(sysctl_perf_counter_limit),
.procname = "perf_counter_max_sample_rate",
.data = &sysctl_perf_counter_sample_rate,
.maxlen = sizeof(sysctl_perf_counter_sample_rate),
.mode = 0644,
.proc_handler = &proc_dointvec,
},