tracing: Some more updates

GIT PULL New Steven Rostedt 1 participant 5 messages Nov 29, 2012 – Dec 14, 2012 Tracing

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Steven Rostedt

author maintainer

2012-11-29 01:24 UTC #0 lore raw

Ingo,

This is based off of my last pull request on tip/perf/core.

Please pull the latest tip/perf/core-2 tree, which can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/perf/core-2

Head SHA1: bf3071f5a054db9e5bab873355d27a7330ce5187

Anton Vorontsov (1):
tracing: Remove unneeded checks from the stack tracer

Dave Jones (1):
tracing: Remove unnecessary WARN_ONCE's from tracing_buffers_splice_read

Hiraku Toyooka (1):
tracing: Add a resize function to make one buffer equivalent to another buffer

----

 kernel/trace/trace.c       |   60 +++++++++++++++++++++++---------------------
 kernel/trace/trace_stack.c |    4 ---
 2 files changed, 31 insertions(+), 33 deletions(-)

Steven Rostedt

author maintainer

2012-11-29 01:25 UTC #1 lore raw

PATCH 1/3 tracing: Add a resize function to make one buffer equivalent to another buffer

From: Hiraku Toyooka <[email protected]>

Trace buffer size is now per-cpu, so that there are the following two patterns in resizing of buffers.

(1) resize per-cpu buffers to same given size
(2) resize per-cpu buffers to another trace_array's buffer size for each CPU (such as preparing the max_tr which is equivalent to the global_trace's size)

__tracing_resize_ring_buffer() can be used for (1), and had implemented (2) inside it for resetting the global_trace to the original size.

(2) was also implemented in another place. So this patch assembles them in a new function - resize_buffer_duplicate_size().

Link http://lkml.kernel.org/r/20121017025616.2627.91226.stgit@falsita open here

Signed-off-by Hiraku Toyooka <[email protected]>

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/trace.c |   58 +++++++++++++++++++++++++++-----------------------
 1 file changed, 31 insertions(+), 27 deletions(-)

kernel/trace/trace.c +31 ~~-27~~

index b69cc38..64ad9bc 100644
@@ -3034,6 +3034,31 @@ static void set_buffer_entries(struct trace_array *tr, unsigned long val)
 		tr->data[cpu]->entries = val;
 }
 
+/* resize @tr's buffer to the size of @size_tr's entries */
+static int resize_buffer_duplicate_size(struct trace_array *tr,
+					struct trace_array *size_tr, int cpu_id)
+{
+	int cpu, ret = 0;
+
+	if (cpu_id == RING_BUFFER_ALL_CPUS) {
+		for_each_tracing_cpu(cpu) {
+			ret = ring_buffer_resize(tr->buffer,
+					size_tr->data[cpu]->entries, cpu);
+			if (ret < 0)
+				break;
+			tr->data[cpu]->entries = size_tr->data[cpu]->entries;
+		}
+	} else {
+		ret = ring_buffer_resize(tr->buffer,
+					size_tr->data[cpu_id]->entries, cpu_id);
+		if (ret == 0)
+			tr->data[cpu_id]->entries =
+				size_tr->data[cpu_id]->entries;
+	}
+
+	return ret;
+}
+
 static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
 {
 	int ret;

@@ -3058,23 +3083,8 @@ static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
 
 	ret = ring_buffer_resize(max_tr.buffer, size, cpu);
 	if (ret < 0) {
-		int r = 0;
-
-		if (cpu == RING_BUFFER_ALL_CPUS) {
-			int i;
-			for_each_tracing_cpu(i) {
-				r = ring_buffer_resize(global_trace.buffer,
-						global_trace.data[i]->entries,
-						i);
-				if (r < 0)
-					break;
-			}
-		} else {
-			r = ring_buffer_resize(global_trace.buffer,
-						global_trace.data[cpu]->entries,
-						cpu);
-		}
-
+		int r = resize_buffer_duplicate_size(&global_trace,
+						     &global_trace, cpu);
 		if (r < 0) {
 			/*
 			 * AARGH! We are left with different

@@ -3212,17 +3222,11 @@ static int tracing_set_tracer(const char *buf)
 
 	topts = create_trace_option_files(t);
 	if (t->use_max_tr) {
-		int cpu;
 		/* we need to make per cpu buffer sizes equivalent */
-		for_each_tracing_cpu(cpu) {
-			ret = ring_buffer_resize(max_tr.buffer,
-						global_trace.data[cpu]->entries,
-						cpu);
-			if (ret < 0)
-				goto out;
-			max_tr.data[cpu]->entries =
-					global_trace.data[cpu]->entries;
-		}
+		ret = resize_buffer_duplicate_size(&max_tr, &global_trace,
+						   RING_BUFFER_ALL_CPUS);
+		if (ret < 0)
+			goto out;
 	}
 
 	if (t->init) {

Signature · 1 line

1.7.10.4

Steven Rostedt

author maintainer

2012-11-29 01:24 UTC #2 lore raw

PATCH 2/3 tracing: Remove unneeded checks from the stack tracer

In reply to Steven Rostedt

From: Anton Vorontsov <[email protected]>

It seems that 'ftrace_enabled' flag should not be used inside the tracer functions. The ftrace core is using this flag for internal purposes, and the flag wasn't meant to be used in tracers' runtime checks.

stack tracer is the only tracer that abusing the flag. So stop it from serving as a bad example.

Also, there is a local 'stack_trace_disabled' flag in the stack tracer, which is never updated; so it can be removed as well.

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Anton Vorontsov <[email protected]>

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/trace_stack.c |    4 ----
 1 file changed, 4 deletions(-)

kernel/trace/trace_stack.c +0 -4

index 0c1b1657..42ca822 100644
@@ -33,7 +33,6 @@ static unsigned long max_stack_size;
 static arch_spinlock_t max_stack_lock =
 	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 
-static int stack_trace_disabled __read_mostly;
 static DEFINE_PER_CPU(int, trace_active);
 static DEFINE_MUTEX(stack_sysctl_mutex);

@@ -116,9 +115,6 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip,
 {
 	int cpu;
 
-	if (unlikely(!ftrace_enabled || stack_trace_disabled))
-		return;
-
 	preempt_disable_notrace();
 
 	cpu = raw_smp_processor_id();

Signature · 1 line

1.7.10.4

Steven Rostedt

author maintainer

2012-11-29 01:24 UTC #3 lore raw

PATCH 3/3 tracing: Remove unnecessary WARN_ONCEs from tracing_buffers_splice_read

In reply to Steven Rostedt

From: Dave Jones <[email protected]>

WARN shouldn't be used as a means of communicating failure to a userspace programmer.

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Dave Jones <[email protected]>

Signed-off-by Steven Rostedt <[email protected]>

---
 kernel/trace/trace.c |    2 --
 1 file changed, 2 deletions(-)

kernel/trace/trace.c +0 -2

index 64ad9bc..5bc3590 100644
@@ -4275,13 +4275,11 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		return -ENOMEM;
 
 	if (*ppos & (PAGE_SIZE - 1)) {
-		WARN_ONCE(1, "Ftrace: previous read must page-align\n");
 		ret = -EINVAL;
 		goto out;
 	}
 
 	if (len & (PAGE_SIZE - 1)) {
-		WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
 		if (len < PAGE_SIZE) {
 			ret = -EINVAL;
 			goto out;

Signature · 1 line

1.7.10.4

Steven Rostedt

author maintainer

2012-12-14 01:17 UTC #4 lore raw

In reply to Steven Rostedt

Quoted 5 lines · Steven Rostedt

Ingo,
This is based off of my last pull request on tip/perf/core.
Please pull the latest tip/perf/core-2 tree, which can be found at:

Ping?

This has been in linux-next for a few weeks too. It's all ready to go in this merge window.

-- Steve

Quoted 20 lines

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/perf/core-2
Head SHA1: bf3071f5a054db9e5bab873355d27a7330ce5187
Anton Vorontsov (1):
tracing: Remove unneeded checks from the stack tracer
Dave Jones (1):
tracing: Remove unnecessary WARN_ONCE's from tracing_buffers_splice_read
Hiraku Toyooka (1):
tracing: Add a resize function to make one buffer equivalent to another buffer
----
 kernel/trace/trace.c       |   60 +++++++++++++++++++++++---------------------
 kernel/trace/trace_stack.c |    4 ---
 2 files changed, 31 insertions(+), 33 deletions(-)