perf_counter: provide an mlock threshold

Provide a threshold to relax the mlock accounting, increasing usability.

Each counter gets perf_counter_mlock_kb for free.

[ Impact: allow more mmap buffering ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090505155437.112113632@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 0fcbf34a4f73..00081d84169f 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -358,6 +358,7 @@ struct file;
 struct perf_mmap_data {
         struct rcu_head                 rcu_head;
         int                             nr_pages;       /* nr of data pages  */
+        int                             nr_locked;      /* nr pages mlocked  */
 
         atomic_t                        poll;           /* POLL_ for wakeups */
         atomic_t                        head;           /* write position    */
@@ -575,6 +576,7 @@ struct perf_callchain_entry {
 extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
 
 extern int sysctl_perf_counter_priv;
+extern int sysctl_perf_counter_mlock;
 
 extern void perf_counter_init(void);