summaryrefslogtreecommitdiffstats
path: root/kernel/trace/ring_buffer.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/trace/ring_buffer.c')
-rw-r--r--kernel/trace/ring_buffer.c71
1 files changed, 50 insertions, 21 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9712083832f4..b21bf14bae9b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -519,6 +519,7 @@ struct ring_buffer_per_cpu {
local_t committing;
local_t commits;
local_t pages_touched;
+ local_t pages_lost;
local_t pages_read;
long last_pages_touch;
size_t shortest_full;
@@ -894,10 +895,18 @@ size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu)
size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu)
{
size_t read;
+ size_t lost;
size_t cnt;
read = local_read(&buffer->buffers[cpu]->pages_read);
+ lost = local_read(&buffer->buffers[cpu]->pages_lost);
cnt = local_read(&buffer->buffers[cpu]->pages_touched);
+
+ if (WARN_ON_ONCE(cnt < lost))
+ return 0;
+
+ cnt -= lost;
+
/* The reader can read an empty page, but not more than that */
if (cnt < read) {
WARN_ON_ONCE(read > cnt + 1);
@@ -907,6 +916,21 @@ size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu)
return cnt - read;
}
+static __always_inline bool full_hit(struct trace_buffer *buffer, int cpu, int full)
+{
+ struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+ size_t nr_pages;
+ size_t dirty;
+
+ nr_pages = cpu_buffer->nr_pages;
+ if (!nr_pages || !full)
+ return true;
+
+ dirty = ring_buffer_nr_dirty_pages(buffer, cpu);
+
+ return (dirty * 100) > (full * nr_pages);
+}
+
/*
* rb_wake_up_waiters - wake up tasks waiting for ring buffer input
*
@@ -1046,22 +1070,20 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
!ring_buffer_empty_cpu(buffer, cpu)) {
unsigned long flags;
bool pagebusy;
- size_t nr_pages;
- size_t dirty;
+ bool done;
if (!full)
break;
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;
- nr_pages = cpu_buffer->nr_pages;
- dirty = ring_buffer_nr_dirty_pages(buffer, cpu);
+ done = !pagebusy && full_hit(buffer, cpu, full);
+
if (!cpu_buffer->shortest_full ||
cpu_buffer->shortest_full > full)
cpu_buffer->shortest_full = full;
raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
- if (!pagebusy &&
- (!nr_pages || (dirty * 100) > full * nr_pages))
+ if (done)
break;
}
@@ -1087,6 +1109,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
* @cpu: the cpu buffer to wait on
* @filp: the file descriptor
* @poll_table: The poll descriptor
+ * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS
*
* If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon
* as data is added to any of the @buffer's cpu buffers. Otherwise
@@ -1096,14 +1119,15 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
* zero otherwise.
*/
__poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
- struct file *filp, poll_table *poll_table)
+ struct file *filp, poll_table *poll_table, int full)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct rb_irq_work *work;
- if (cpu == RING_BUFFER_ALL_CPUS)
+ if (cpu == RING_BUFFER_ALL_CPUS) {
work = &buffer->irq_work;
- else {
+ full = 0;
+ } else {
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return -EINVAL;
@@ -1111,8 +1135,14 @@ __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
work = &cpu_buffer->irq_work;
}
- poll_wait(filp, &work->waiters, poll_table);
- work->waiters_pending = true;
+ if (full) {
+ poll_wait(filp, &work->full_waiters, poll_table);
+ work->full_waiters_pending = true;
+ } else {
+ poll_wait(filp, &work->waiters, poll_table);
+ work->waiters_pending = true;
+ }
+
/*
* There's a tight race between setting the waiters_pending and
* checking if the ring buffer is empty. Once the waiters_pending bit
@@ -1128,6 +1158,9 @@ __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
*/
smp_mb();
+ if (full)
+ return full_hit(buffer, cpu, full) ? EPOLLIN | EPOLLRDNORM : 0;
+
if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
(cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
return EPOLLIN | EPOLLRDNORM;
@@ -1769,9 +1802,9 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
free_buffer_page(cpu_buffer->reader_page);
- rb_head_page_deactivate(cpu_buffer);
-
if (head) {
+ rb_head_page_deactivate(cpu_buffer);
+
list_for_each_entry_safe(bpage, tmp, head, list) {
list_del_init(&bpage->list);
free_buffer_page(bpage);
@@ -2007,6 +2040,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages)
*/
local_add(page_entries, &cpu_buffer->overrun);
local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes);
+ local_inc(&cpu_buffer->pages_lost);
}
/*
@@ -2491,6 +2525,7 @@ rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer,
*/
local_add(entries, &cpu_buffer->overrun);
local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes);
+ local_inc(&cpu_buffer->pages_lost);
/*
* The entries will be zeroed out when we move the
@@ -3155,10 +3190,6 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer,
static __always_inline void
rb_wakeups(struct trace_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
{
- size_t nr_pages;
- size_t dirty;
- size_t full;
-
if (buffer->irq_work.waiters_pending) {
buffer->irq_work.waiters_pending = false;
/* irq_work_queue() supplies it's own memory barriers */
@@ -3182,10 +3213,7 @@ rb_wakeups(struct trace_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
cpu_buffer->last_pages_touch = local_read(&cpu_buffer->pages_touched);
- full = cpu_buffer->shortest_full;
- nr_pages = cpu_buffer->nr_pages;
- dirty = ring_buffer_nr_dirty_pages(buffer, cpu_buffer->cpu);
- if (full && nr_pages && (dirty * 100) <= full * nr_pages)
+ if (!full_hit(buffer, cpu_buffer->cpu, cpu_buffer->shortest_full))
return;
cpu_buffer->irq_work.wakeup_full = true;
@@ -5248,6 +5276,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
local_set(&cpu_buffer->committing, 0);
local_set(&cpu_buffer->commits, 0);
local_set(&cpu_buffer->pages_touched, 0);
+ local_set(&cpu_buffer->pages_lost, 0);
local_set(&cpu_buffer->pages_read, 0);
cpu_buffer->last_pages_touch = 0;
cpu_buffer->shortest_full = 0;