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perf_counter: Change data head from u32 to u64

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Since some people worried that 4G might not be a large enough
as an mmap data window, extend it to 64 bit for capable
platforms.

Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-06-02 16:16:02 +02:00 committed by Ingo Molnar
parent e4abb5d4f7
commit 8e3747c13c
2 changed files with 12 additions and 10 deletions
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7
include/linux/perf_counter.h
View file

@ -212,7 +212,7 @@ struct perf_counter_mmap_page {
* User-space reading this value should issue an rmb(), on SMP capable
* platforms, after reading this value -- see perf_counter_wakeup().
*/
__u32 data_head; /* head in the data section */
__u64 data_head; /* head in the data section */
};
#define PERF_EVENT_MISC_CPUMODE_MASK (3 << 0)
@ -397,10 +397,11 @@ struct perf_mmap_data {
int nr_locked; /* nr pages mlocked */
atomic_t poll; /* POLL_ for wakeups */
atomic_t head; /* write position */
atomic_t events; /* event limit */
atomic_t done_head; /* completed head */
atomic_long_t head; /* write position */
atomic_long_t done_head; /* completed head */
atomic_t lock; /* concurrent writes */
atomic_t wakeup; /* needs a wakeup */

15
kernel/perf_counter.c
View file

@ -2067,8 +2067,8 @@ __weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
struct perf_output_handle {
struct perf_counter *counter;
struct perf_mmap_data *data;
unsigned int offset;
unsigned int head;
unsigned long head;
unsigned long offset;
int nmi;
int overflow;
int locked;
@ -2122,7 +2122,8 @@ static void perf_output_lock(struct perf_output_handle *handle)
static void perf_output_unlock(struct perf_output_handle *handle)
{
struct perf_mmap_data *data = handle->data;
int head, cpu;
unsigned long head;
int cpu;
data->done_head = data->head;
@ -2135,7 +2136,7 @@ again:
* before we publish the new head, matched by a rmb() in userspace when
* reading this position.
*/
while ((head = atomic_xchg(&data->done_head, 0)))
while ((head = atomic_long_xchg(&data->done_head, 0)))
data->user_page->data_head = head;
/*
@ -2148,7 +2149,7 @@ again:
/*
* Therefore we have to validate we did not indeed do so.
*/
if (unlikely(atomic_read(&data->done_head))) {
if (unlikely(atomic_long_read(&data->done_head))) {
/*
* Since we had it locked, we can lock it again.
*/
@ -2195,7 +2196,7 @@ static int perf_output_begin(struct perf_output_handle *handle,
do {
offset = head = atomic_read(&data->head);
head += size;
} while (atomic_cmpxchg(&data->head, offset, head) != offset);
} while (atomic_long_cmpxchg(&data->head, offset, head) != offset);
handle->offset = offset;
handle->head = head;
@ -2246,7 +2247,7 @@ static void perf_output_copy(struct perf_output_handle *handle,
* Check we didn't copy past our reservation window, taking the
* possible unsigned int wrap into account.
*/
WARN_ON_ONCE(((int)(handle->head - handle->offset)) < 0);
WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0);
}
#define perf_output_put(handle, x) \