[tip:perf/core] perf: Optimize the !vmalloc backed buffer

tip-bot for Peter Zijlstra
2010-05-21T11:30:46Z

Commit-ID: 3cafa9fbb5c1d564b7b8e7224f493effbf04ffee
Gitweb: http://git.kernel.org/tip/3cafa9fbb5c1d564b7b8e7224f493effbf04ffee
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 20 May 2010 19:07:56 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 21 May 2010 11:37:59 +0200

perf: Optimize the !vmalloc backed buffer

Reduce code and data by using the knowledge that for
!PERF_USE_VMALLOC data_order is always 0.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100521090710.795019386@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/perf_event.h | 2 +-
kernel/perf_event.c | 41 ++++++++++++++++++++++++++---------------
2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7bd17f0..09cd9c1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -588,8 +588,8 @@ struct perf_mmap_data {
struct rcu_head rcu_head;
#ifdef CONFIG_PERF_USE_VMALLOC
struct work_struct work;
+ int page_order; /* allocation order */
#endif
- int data_order; /* allocation order */
int nr_pages; /* nr of data pages */
int writable; /* are we writable */
int nr_locked; /* nr pages mlocked */
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index b67549a..953ce46 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2297,11 +2297,6 @@ unlock:
rcu_read_unlock();
}

-static unsigned long perf_data_size(struct perf_mmap_data *data)
-{
- return data->nr_pages << (PAGE_SHIFT + data->data_order);
-}
-
#ifndef CONFIG_PERF_USE_VMALLOC

/*
@@ -2359,7 +2354,6 @@ perf_mmap_data_alloc(struct perf_event *event, int nr_pages)
goto fail_data_pages;
}

- data->data_order = 0;
data->nr_pages = nr_pages;

return data;
@@ -2395,6 +2389,11 @@ static void perf_mmap_data_free(struct perf_mmap_data *data)
kfree(data);
}

+static inline int page_order(struct perf_mmap_data *data)
+{
+ return 0;
+}
+
#else

/*
@@ -2403,10 +2402,15 @@ static void perf_mmap_data_free(struct perf_mmap_data *data)
* Required for architectures that have d-cache aliasing issues.
*/

+static inline int page_order(struct perf_mmap_data *data)
+{
+ return data->page_order;
+}
+
static struct page *
perf_mmap_to_page(struct perf_mmap_data *data, unsigned long pgoff)
{
- if (pgoff > (1UL << data->data_order))
+ if (pgoff > (1UL << page_order(data)))
return NULL;

return vmalloc_to_page((void *)data->user_page + pgoff * PAGE_SIZE);
@@ -2426,7 +2430,7 @@ static void perf_mmap_data_free_work(struct work_struct *work)
int i, nr;

data = container_of(work, struct perf_mmap_data, work);
- nr = 1 << data->data_order;
+ nr = 1 << page_order(data);

base = data->user_page;
for (i = 0; i < nr + 1; i++)
@@ -2465,7 +2469,7 @@ perf_mmap_data_alloc(struct perf_event *event, int nr_pages)

data->user_page = all_buf;
data->data_pages[0] = all_buf + PAGE_SIZE;
- data->data_order = ilog2(nr_pages);
+ data->page_order = ilog2(nr_pages);
data->nr_pages = 1;

return data;
@@ -2479,6 +2483,11 @@ fail:

#endif

+static unsigned long perf_data_size(struct perf_mmap_data *data)
+{
+ return data->nr_pages << (PAGE_SHIFT + page_order(data));
+}
+
static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct perf_event *event = vma->vm_file->private_data;
@@ -2979,10 +2988,12 @@ void perf_output_copy(struct perf_output_handle *handle,
handle->addr += size;
handle->size -= size;
if (!handle->size) {
+ struct perf_mmap_data *data = handle->data;
+
handle->page++;
- handle->page &= handle->data->nr_pages - 1;
- handle->addr = handle->data->data_pages[handle->page];
- handle->size = PAGE_SIZE << handle->data->data_order;
+ handle->page &= data->nr_pages - 1;
+ handle->addr = data->data_pages[handle->page];
+ handle->size = PAGE_SIZE << page_order(data);
}
} while (len);
}
@@ -3050,12 +3061,12 @@ int perf_output_begin(struct perf_output_handle *handle,
if (head - local_read(&data->wakeup) > data->watermark)
local_add(data->watermark, &data->wakeup);

- handle->page = handle->offset >> (PAGE_SHIFT + data->data_order);
+ handle->page = handle->offset >> (PAGE_SHIFT + page_order(data));
handle->page &= data->nr_pages - 1;
- handle->size = handle->offset & ((PAGE_SIZE << data->data_order) - 1);
+ handle->size = handle->offset & ((PAGE_SIZE << page_order(data)) - 1);
handle->addr = data->data_pages[handle->page];
handle->addr += handle->size;
- handle->size = (PAGE_SIZE << data->data_order) - handle->size;
+ handle->size = (PAGE_SIZE << page_order(data)) - handle->size;

if (have_lost) {
lost_event.header.type = PERF_RECORD_LOST;