Commit b9cacc7b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar

perf_counter: more elaborate write API

Provide a begin, copy, end interface to the output buffer.

begin() reserves the space,
 copy() copies the data over, considering page boundaries,
  end() finalizes the event and does the wakeup.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Orig-LKML-Reference: <20090325113316.740550870@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c7138f37
...@@ -9,6 +9,7 @@ ...@@ -9,6 +9,7 @@
*/ */
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/mm.h>
#include <linux/cpu.h> #include <linux/cpu.h>
#include <linux/smp.h> #include <linux/smp.h>
#include <linux/file.h> #include <linux/file.h>
...@@ -16,15 +17,14 @@ ...@@ -16,15 +17,14 @@
#include <linux/sysfs.h> #include <linux/sysfs.h>
#include <linux/ptrace.h> #include <linux/ptrace.h>
#include <linux/percpu.h> #include <linux/percpu.h>
#include <linux/vmstat.h>
#include <linux/hardirq.h>
#include <linux/rculist.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/syscalls.h> #include <linux/syscalls.h>
#include <linux/anon_inodes.h> #include <linux/anon_inodes.h>
#include <linux/kernel_stat.h> #include <linux/kernel_stat.h>
#include <linux/perf_counter.h> #include <linux/perf_counter.h>
#include <linux/mm.h>
#include <linux/vmstat.h>
#include <linux/rculist.h>
#include <linux/hardirq.h>
#include <asm/irq_regs.h> #include <asm/irq_regs.h>
...@@ -1411,16 +1411,20 @@ static const struct file_operations perf_fops = { ...@@ -1411,16 +1411,20 @@ static const struct file_operations perf_fops = {
* Output * Output
*/ */
static int perf_output_write(struct perf_counter *counter, int nmi, struct perf_output_handle {
void *buf, ssize_t size) struct perf_counter *counter;
struct perf_mmap_data *data;
unsigned int offset;
int wakeup;
};
static int perf_output_begin(struct perf_output_handle *handle,
struct perf_counter *counter, unsigned int size)
{ {
struct perf_mmap_data *data; struct perf_mmap_data *data;
unsigned int offset, head, nr; unsigned int offset, head;
unsigned int len;
int ret, wakeup;
rcu_read_lock(); rcu_read_lock();
ret = -ENOSPC;
data = rcu_dereference(counter->data); data = rcu_dereference(counter->data);
if (!data) if (!data)
goto out; goto out;
...@@ -1428,45 +1432,82 @@ static int perf_output_write(struct perf_counter *counter, int nmi, ...@@ -1428,45 +1432,82 @@ static int perf_output_write(struct perf_counter *counter, int nmi,
if (!data->nr_pages) if (!data->nr_pages)
goto out; goto out;
ret = -EINVAL;
if (size > PAGE_SIZE)
goto out;
do { do {
offset = head = atomic_read(&data->head); offset = head = atomic_read(&data->head);
head += size; head += size;
} while (atomic_cmpxchg(&data->head, offset, head) != offset); } while (atomic_cmpxchg(&data->head, offset, head) != offset);
wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT); handle->counter = counter;
handle->data = data;
handle->offset = offset;
handle->wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT);
nr = (offset >> PAGE_SHIFT) & (data->nr_pages - 1); return 0;
offset &= PAGE_SIZE - 1;
len = min_t(unsigned int, PAGE_SIZE - offset, size); out:
memcpy(data->data_pages[nr] + offset, buf, len); rcu_read_unlock();
size -= len;
if (size) { return -ENOSPC;
nr = (nr + 1) & (data->nr_pages - 1); }
memcpy(data->data_pages[nr], buf + len, size);
}
/* static void perf_output_copy(struct perf_output_handle *handle,
* generate a poll() wakeup for every page boundary crossed void *buf, unsigned int len)
*/ {
if (wakeup) { unsigned int pages_mask;
atomic_xchg(&data->wakeup, POLL_IN); unsigned int offset;
__perf_counter_update_userpage(counter, data); unsigned int size;
void **pages;
offset = handle->offset;
pages_mask = handle->data->nr_pages - 1;
pages = handle->data->data_pages;
do {
unsigned int page_offset;
int nr;
nr = (offset >> PAGE_SHIFT) & pages_mask;
page_offset = offset & (PAGE_SIZE - 1);
size = min_t(unsigned int, PAGE_SIZE - page_offset, len);
memcpy(pages[nr] + page_offset, buf, size);
len -= size;
buf += size;
offset += size;
} while (len);
handle->offset = offset;
}
static void perf_output_end(struct perf_output_handle *handle, int nmi)
{
if (handle->wakeup) {
(void)atomic_xchg(&handle->data->wakeup, POLL_IN);
__perf_counter_update_userpage(handle->counter, handle->data);
if (nmi) { if (nmi) {
counter->wakeup_pending = 1; handle->counter->wakeup_pending = 1;
set_perf_counter_pending(); set_perf_counter_pending();
} else } else
wake_up(&counter->waitq); wake_up(&handle->counter->waitq);
} }
ret = 0;
out:
rcu_read_unlock(); rcu_read_unlock();
}
static int perf_output_write(struct perf_counter *counter, int nmi,
void *buf, ssize_t size)
{
struct perf_output_handle handle;
int ret;
ret = perf_output_begin(&handle, counter, size);
if (ret)
goto out;
perf_output_copy(&handle, buf, size);
perf_output_end(&handle, nmi);
out:
return ret; return ret;
} }
......
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