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authorIngo Molnar <mingo@elte.hu>2009-06-20 17:25:49 +0200
committerIngo Molnar <mingo@elte.hu>2009-06-20 17:25:49 +0200
commit3daeb4da9a0b056bdc4af003e5605c1da4c0b068 (patch)
treea17fda13d9be51c71880a8ce2c55eaf7337c722f /kernel
parent9ea1a153a4fb435c22e9988784bb476671286112 (diff)
parent4b221f0313f0f7f1f7aa0a1fd16ad400840def26 (diff)
downloadlinux-2.6.34-ux500-3daeb4da9a0b056bdc4af003e5605c1da4c0b068.tar.gz
Merge branch 'tip/tracing/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/urgent
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ring_buffer.c82
-rw-r--r--kernel/trace/ring_buffer_benchmark.c37
2 files changed, 78 insertions, 41 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ed3559944fc..589b3eedfa6 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -620,12 +620,6 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
kfree(cpu_buffer);
}
-/*
- * Causes compile errors if the struct buffer_page gets bigger
- * than the struct page.
- */
-extern int ring_buffer_page_too_big(void);
-
#ifdef CONFIG_HOTPLUG_CPU
static int rb_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu);
@@ -648,11 +642,6 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
int bsize;
int cpu;
- /* Paranoid! Optimizes out when all is well */
- if (sizeof(struct buffer_page) > sizeof(struct page))
- ring_buffer_page_too_big();
-
-
/* keep it in its own cache line */
buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()),
GFP_KERNEL);
@@ -668,8 +657,8 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
buffer->reader_lock_key = key;
/* need at least two pages */
- if (buffer->pages == 1)
- buffer->pages++;
+ if (buffer->pages < 2)
+ buffer->pages = 2;
/*
* In case of non-hotplug cpu, if the ring-buffer is allocated
@@ -1013,7 +1002,7 @@ rb_event_index(struct ring_buffer_event *event)
{
unsigned long addr = (unsigned long)event;
- return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE);
+ return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE;
}
static inline int
@@ -1334,9 +1323,6 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
/* We reserved something on the buffer */
- if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE))
- return NULL;
-
event = __rb_page_index(tail_page, tail);
rb_update_event(event, type, length);
@@ -2480,6 +2466,21 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
}
EXPORT_SYMBOL_GPL(ring_buffer_iter_peek);
+static inline int rb_ok_to_lock(void)
+{
+ /*
+ * If an NMI die dumps out the content of the ring buffer
+ * do not grab locks. We also permanently disable the ring
+ * buffer too. A one time deal is all you get from reading
+ * the ring buffer from an NMI.
+ */
+ if (likely(!in_nmi() && !oops_in_progress))
+ return 1;
+
+ tracing_off_permanent();
+ return 0;
+}
+
/**
* ring_buffer_peek - peek at the next event to be read
* @buffer: The ring buffer to read
@@ -2495,14 +2496,20 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
struct ring_buffer_event *event;
unsigned long flags;
+ int dolock;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return NULL;
+ dolock = rb_ok_to_lock();
again:
- spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ local_irq_save(flags);
+ if (dolock)
+ spin_lock(&cpu_buffer->reader_lock);
event = rb_buffer_peek(buffer, cpu, ts);
- spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ if (dolock)
+ spin_unlock(&cpu_buffer->reader_lock);
+ local_irq_restore(flags);
if (event && event->type_len == RINGBUF_TYPE_PADDING) {
cpu_relax();
@@ -2554,6 +2561,9 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event = NULL;
unsigned long flags;
+ int dolock;
+
+ dolock = rb_ok_to_lock();
again:
/* might be called in atomic */
@@ -2563,7 +2573,9 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
goto out;
cpu_buffer = buffer->buffers[cpu];
- spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ local_irq_save(flags);
+ if (dolock)
+ spin_lock(&cpu_buffer->reader_lock);
event = rb_buffer_peek(buffer, cpu, ts);
if (!event)
@@ -2572,7 +2584,9 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
rb_advance_reader(cpu_buffer);
out_unlock:
- spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ if (dolock)
+ spin_unlock(&cpu_buffer->reader_lock);
+ local_irq_restore(flags);
out:
preempt_enable();
@@ -2770,12 +2784,25 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset);
int ring_buffer_empty(struct ring_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
+ unsigned long flags;
+ int dolock;
int cpu;
+ int ret;
+
+ dolock = rb_ok_to_lock();
/* yes this is racy, but if you don't like the race, lock the buffer */
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
- if (!rb_per_cpu_empty(cpu_buffer))
+ local_irq_save(flags);
+ if (dolock)
+ spin_lock(&cpu_buffer->reader_lock);
+ ret = rb_per_cpu_empty(cpu_buffer);
+ if (dolock)
+ spin_unlock(&cpu_buffer->reader_lock);
+ local_irq_restore(flags);
+
+ if (!ret)
return 0;
}
@@ -2791,14 +2818,23 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty);
int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
+ unsigned long flags;
+ int dolock;
int ret;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return 1;
+ dolock = rb_ok_to_lock();
+
cpu_buffer = buffer->buffers[cpu];
+ local_irq_save(flags);
+ if (dolock)
+ spin_lock(&cpu_buffer->reader_lock);
ret = rb_per_cpu_empty(cpu_buffer);
-
+ if (dolock)
+ spin_unlock(&cpu_buffer->reader_lock);
+ local_irq_restore(flags);
return ret;
}
diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index cf6b0f50134..573d3cc762c 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -203,7 +203,7 @@ static void ring_buffer_producer(void)
* Hammer the buffer for 10 secs (this may
* make the system stall)
*/
- pr_info("Starting ring buffer hammer\n");
+ trace_printk("Starting ring buffer hammer\n");
do_gettimeofday(&start_tv);
do {
struct ring_buffer_event *event;
@@ -239,7 +239,7 @@ static void ring_buffer_producer(void)
#endif
} while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
- pr_info("End ring buffer hammer\n");
+ trace_printk("End ring buffer hammer\n");
if (consumer) {
/* Init both completions here to avoid races */
@@ -262,49 +262,50 @@ static void ring_buffer_producer(void)
overruns = ring_buffer_overruns(buffer);
if (kill_test)
- pr_info("ERROR!\n");
- pr_info("Time: %lld (usecs)\n", time);
- pr_info("Overruns: %lld\n", overruns);
+ trace_printk("ERROR!\n");
+ trace_printk("Time: %lld (usecs)\n", time);
+ trace_printk("Overruns: %lld\n", overruns);
if (disable_reader)
- pr_info("Read: (reader disabled)\n");
+ trace_printk("Read: (reader disabled)\n");
else
- pr_info("Read: %ld (by %s)\n", read,
+ trace_printk("Read: %ld (by %s)\n", read,
read_events ? "events" : "pages");
- pr_info("Entries: %lld\n", entries);
- pr_info("Total: %lld\n", entries + overruns + read);
- pr_info("Missed: %ld\n", missed);
- pr_info("Hit: %ld\n", hit);
+ trace_printk("Entries: %lld\n", entries);
+ trace_printk("Total: %lld\n", entries + overruns + read);
+ trace_printk("Missed: %ld\n", missed);
+ trace_printk("Hit: %ld\n", hit);
/* Convert time from usecs to millisecs */
do_div(time, USEC_PER_MSEC);
if (time)
hit /= (long)time;
else
- pr_info("TIME IS ZERO??\n");
+ trace_printk("TIME IS ZERO??\n");
- pr_info("Entries per millisec: %ld\n", hit);
+ trace_printk("Entries per millisec: %ld\n", hit);
if (hit) {
/* Calculate the average time in nanosecs */
avg = NSEC_PER_MSEC / hit;
- pr_info("%ld ns per entry\n", avg);
+ trace_printk("%ld ns per entry\n", avg);
}
if (missed) {
if (time)
missed /= (long)time;
- pr_info("Total iterations per millisec: %ld\n", hit + missed);
+ trace_printk("Total iterations per millisec: %ld\n",
+ hit + missed);
/* it is possible that hit + missed will overflow and be zero */
if (!(hit + missed)) {
- pr_info("hit + missed overflowed and totalled zero!\n");
+ trace_printk("hit + missed overflowed and totalled zero!\n");
hit--; /* make it non zero */
}
/* Caculate the average time in nanosecs */
avg = NSEC_PER_MSEC / (hit + missed);
- pr_info("%ld ns per entry\n", avg);
+ trace_printk("%ld ns per entry\n", avg);
}
}
@@ -355,7 +356,7 @@ static int ring_buffer_producer_thread(void *arg)
ring_buffer_producer();
- pr_info("Sleeping for 10 secs\n");
+ trace_printk("Sleeping for 10 secs\n");
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(HZ * SLEEP_TIME);
__set_current_state(TASK_RUNNING);