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Message-ID: <1273795880.27703.1610.camel@gandalf.stny.rr.com>
Date: Thu, 13 May 2010 20:11:20 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Ingo Molnar <mingo@...e.hu>,
Frederic Weisbecker <fweisbec@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: [PATCH][GIT PULL] ring-buffer: Add cached pages when freeing
reader page
Ingo,
This includes the updates in core-2.
Please pull the latest tip/tracing/core-3 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/core-3
Steven Rostedt (1):
ring-buffer: Add cached pages when freeing reader page
----
kernel/trace/ring_buffer.c | 52 ++++++++++++++++++++++++++++++++++++++------
1 files changed, 45 insertions(+), 7 deletions(-)
---------------------------
commit 9d70909920a69e431348c6d5cf46e72d4e3514bc
Author: Steven Rostedt <srostedt@...hat.com>
Date: Thu May 13 15:33:06 2010 -0400
ring-buffer: Add cached pages when freeing reader page
When the pages are removed from the ring buffer for things like
splice they are freed with ring_buffer_free_read_page().
They are also allocated with ring_buffer_alloc_read_page().
Currently the ring buffer does not take advantage of this situation.
Every time the page is freed, the ring buffer simply frees it.
When a new page is needed, it allocates it. This means that reading
several pages with splice will cause a page to be freed and allocated
several times. This is simply a waste.
This patch adds a cache of the pages freed (16 max). This allows
the pages to be reused quickly without need to go back to the memory
pool.
v2: Added in locking that should have been there in the first release.
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7f6059c..7aded7d 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -157,6 +157,8 @@ static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON;
#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data)
+#define RB_MAX_FREE_PAGES 16
+
/**
* tracing_on - enable all tracing buffers
*
@@ -325,7 +327,10 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data);
#define RB_MISSED_STORED (1 << 30)
struct buffer_data_page {
- u64 time_stamp; /* page time stamp */
+ union {
+ struct buffer_data_page *next; /* for free pages */
+ u64 time_stamp; /* page time stamp */
+ };
local_t commit; /* write committed index */
unsigned char data[]; /* data of buffer page */
};
@@ -472,6 +477,10 @@ struct ring_buffer {
atomic_t record_disabled;
cpumask_var_t cpumask;
+ struct buffer_data_page *free_pages;
+ int nr_free_pages;
+ spinlock_t free_pages_lock;
+
struct lock_class_key *reader_lock_key;
struct mutex mutex;
@@ -1118,6 +1127,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
buffer->flags = flags;
buffer->clock = trace_clock_local;
buffer->reader_lock_key = key;
+ spin_lock_init(&buffer->free_pages_lock);
/* need at least two pages */
if (buffer->pages < 2)
@@ -1184,6 +1194,7 @@ EXPORT_SYMBOL_GPL(__ring_buffer_alloc);
void
ring_buffer_free(struct ring_buffer *buffer)
{
+ struct buffer_data_page *bpage;
int cpu;
get_online_cpus();
@@ -1200,6 +1211,11 @@ ring_buffer_free(struct ring_buffer *buffer)
kfree(buffer->buffers);
free_cpumask_var(buffer->cpumask);
+ while (buffer->free_pages) {
+ bpage = buffer->free_pages;
+ buffer->free_pages = bpage->next;
+ free_page((unsigned long)bpage);
+ };
kfree(buffer);
}
EXPORT_SYMBOL_GPL(ring_buffer_free);
@@ -3714,14 +3730,24 @@ EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
*/
void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
{
- struct buffer_data_page *bpage;
+ struct buffer_data_page *bpage = NULL;
unsigned long addr;
- addr = __get_free_page(GFP_KERNEL);
- if (!addr)
- return NULL;
+ spin_lock(&buffer->free_pages_lock);
+ if (buffer->free_pages) {
+ bpage = buffer->free_pages;
+ buffer->free_pages = bpage->next;
+ buffer->nr_free_pages--;
+ }
+ spin_unlock(&buffer->free_pages_lock);
- bpage = (void *)addr;
+ if (!bpage) {
+ addr = __get_free_page(GFP_KERNEL);
+ if (!addr)
+ return NULL;
+
+ bpage = (void *)addr;
+ }
rb_init_page(bpage);
@@ -3738,7 +3764,19 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page);
*/
void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
{
- free_page((unsigned long)data);
+ struct buffer_data_page *bpage = data;
+
+ spin_lock(&buffer->free_pages_lock);
+ if (buffer->nr_free_pages >= RB_MAX_FREE_PAGES) {
+ spin_unlock(&buffer->free_pages_lock);
+ free_page((unsigned long)data);
+ return;
+ }
+
+ bpage->next = buffer->free_pages;
+ buffer->free_pages = bpage;
+ buffer->nr_free_pages++;
+ spin_unlock(&buffer->free_pages_lock);
}
EXPORT_SYMBOL_GPL(ring_buffer_free_read_page);
--
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