ring-buffer: Add per_cpu ring buffer control files
Add a debugfs entry under per_cpu/ folder for each cpu called
buffer_size_kb to control the ring buffer size for each CPU
independently.
If the global file buffer_size_kb is used to set size, the individual
ring buffers will be adjusted to the given size. The buffer_size_kb will
report the common size to maintain backward compatibility.
If the buffer_size_kb file under the per_cpu/ directory is used to
change buffer size for a specific CPU, only the size of the respective
ring buffer is updated. When tracing/buffer_size_kb is read, it reports
'X' to indicate that sizes of per_cpu ring buffers are not equivalent.
Link: http://lkml.kernel.org/r/1328212844-11889-1-git-send-email-vnagarnaik@google.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Justin Teravest <teravest@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bbcde54..f11a285 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -838,7 +838,8 @@
/* If we expanded the buffers, make sure the max is expanded too */
if (ring_buffer_expanded && type->use_max_tr)
- ring_buffer_resize(max_tr.buffer, trace_buf_size);
+ ring_buffer_resize(max_tr.buffer, trace_buf_size,
+ RING_BUFFER_ALL_CPUS);
/* the test is responsible for initializing and enabling */
pr_info("Testing tracer %s: ", type->name);
@@ -854,7 +855,8 @@
/* Shrink the max buffer again */
if (ring_buffer_expanded && type->use_max_tr)
- ring_buffer_resize(max_tr.buffer, 1);
+ ring_buffer_resize(max_tr.buffer, 1,
+ RING_BUFFER_ALL_CPUS);
printk(KERN_CONT "PASSED\n");
}
@@ -3053,7 +3055,14 @@
return t->init(tr);
}
-static int __tracing_resize_ring_buffer(unsigned long size)
+static void set_buffer_entries(struct trace_array *tr, unsigned long val)
+{
+ int cpu;
+ for_each_tracing_cpu(cpu)
+ tr->data[cpu]->entries = val;
+}
+
+static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
{
int ret;
@@ -3064,19 +3073,32 @@
*/
ring_buffer_expanded = 1;
- ret = ring_buffer_resize(global_trace.buffer, size);
+ ret = ring_buffer_resize(global_trace.buffer, size, cpu);
if (ret < 0)
return ret;
if (!current_trace->use_max_tr)
goto out;
- ret = ring_buffer_resize(max_tr.buffer, size);
+ ret = ring_buffer_resize(max_tr.buffer, size, cpu);
if (ret < 0) {
- int r;
+ int r = 0;
- r = ring_buffer_resize(global_trace.buffer,
- global_trace.entries);
+ 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);
+ }
+
if (r < 0) {
/*
* AARGH! We are left with different
@@ -3098,14 +3120,21 @@
return ret;
}
- max_tr.entries = size;
+ if (cpu == RING_BUFFER_ALL_CPUS)
+ set_buffer_entries(&max_tr, size);
+ else
+ max_tr.data[cpu]->entries = size;
+
out:
- global_trace.entries = size;
+ if (cpu == RING_BUFFER_ALL_CPUS)
+ set_buffer_entries(&global_trace, size);
+ else
+ global_trace.data[cpu]->entries = size;
return ret;
}
-static ssize_t tracing_resize_ring_buffer(unsigned long size)
+static ssize_t tracing_resize_ring_buffer(unsigned long size, int cpu_id)
{
int cpu, ret = size;
@@ -3121,12 +3150,19 @@
atomic_inc(&max_tr.data[cpu]->disabled);
}
- if (size != global_trace.entries)
- ret = __tracing_resize_ring_buffer(size);
+ if (cpu_id != RING_BUFFER_ALL_CPUS) {
+ /* make sure, this cpu is enabled in the mask */
+ if (!cpumask_test_cpu(cpu_id, tracing_buffer_mask)) {
+ ret = -EINVAL;
+ goto out;
+ }
+ }
+ ret = __tracing_resize_ring_buffer(size, cpu_id);
if (ret < 0)
ret = -ENOMEM;
+out:
for_each_tracing_cpu(cpu) {
if (global_trace.data[cpu])
atomic_dec(&global_trace.data[cpu]->disabled);
@@ -3157,7 +3193,8 @@
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded)
- ret = __tracing_resize_ring_buffer(trace_buf_size);
+ ret = __tracing_resize_ring_buffer(trace_buf_size,
+ RING_BUFFER_ALL_CPUS);
mutex_unlock(&trace_types_lock);
return ret;
@@ -3181,7 +3218,8 @@
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded) {
- ret = __tracing_resize_ring_buffer(trace_buf_size);
+ ret = __tracing_resize_ring_buffer(trace_buf_size,
+ RING_BUFFER_ALL_CPUS);
if (ret < 0)
goto out;
ret = 0;
@@ -3207,8 +3245,8 @@
* The max_tr ring buffer has some state (e.g. ring->clock) and
* we want preserve it.
*/
- ring_buffer_resize(max_tr.buffer, 1);
- max_tr.entries = 1;
+ ring_buffer_resize(max_tr.buffer, 1, RING_BUFFER_ALL_CPUS);
+ set_buffer_entries(&max_tr, 1);
}
destroy_trace_option_files(topts);
@@ -3216,10 +3254,17 @@
topts = create_trace_option_files(current_trace);
if (current_trace->use_max_tr) {
- ret = ring_buffer_resize(max_tr.buffer, global_trace.entries);
- if (ret < 0)
- goto out;
- max_tr.entries = global_trace.entries;
+ 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;
+ }
}
if (t->init) {
@@ -3721,30 +3766,82 @@
goto out;
}
+struct ftrace_entries_info {
+ struct trace_array *tr;
+ int cpu;
+};
+
+static int tracing_entries_open(struct inode *inode, struct file *filp)
+{
+ struct ftrace_entries_info *info;
+
+ if (tracing_disabled)
+ return -ENODEV;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ info->tr = &global_trace;
+ info->cpu = (unsigned long)inode->i_private;
+
+ filp->private_data = info;
+
+ return 0;
+}
+
static ssize_t
tracing_entries_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
- struct trace_array *tr = filp->private_data;
- char buf[96];
- int r;
+ struct ftrace_entries_info *info = filp->private_data;
+ struct trace_array *tr = info->tr;
+ char buf[64];
+ int r = 0;
+ ssize_t ret;
mutex_lock(&trace_types_lock);
- if (!ring_buffer_expanded)
- r = sprintf(buf, "%lu (expanded: %lu)\n",
- tr->entries >> 10,
- trace_buf_size >> 10);
- else
- r = sprintf(buf, "%lu\n", tr->entries >> 10);
+
+ if (info->cpu == RING_BUFFER_ALL_CPUS) {
+ int cpu, buf_size_same;
+ unsigned long size;
+
+ size = 0;
+ buf_size_same = 1;
+ /* check if all cpu sizes are same */
+ for_each_tracing_cpu(cpu) {
+ /* fill in the size from first enabled cpu */
+ if (size == 0)
+ size = tr->data[cpu]->entries;
+ if (size != tr->data[cpu]->entries) {
+ buf_size_same = 0;
+ break;
+ }
+ }
+
+ if (buf_size_same) {
+ if (!ring_buffer_expanded)
+ r = sprintf(buf, "%lu (expanded: %lu)\n",
+ size >> 10,
+ trace_buf_size >> 10);
+ else
+ r = sprintf(buf, "%lu\n", size >> 10);
+ } else
+ r = sprintf(buf, "X\n");
+ } else
+ r = sprintf(buf, "%lu\n", tr->data[info->cpu]->entries >> 10);
+
mutex_unlock(&trace_types_lock);
- return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+ ret = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+ return ret;
}
static ssize_t
tracing_entries_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
+ struct ftrace_entries_info *info = filp->private_data;
unsigned long val;
int ret;
@@ -3759,7 +3856,7 @@
/* value is in KB */
val <<= 10;
- ret = tracing_resize_ring_buffer(val);
+ ret = tracing_resize_ring_buffer(val, info->cpu);
if (ret < 0)
return ret;
@@ -3768,6 +3865,16 @@
return cnt;
}
+static int
+tracing_entries_release(struct inode *inode, struct file *filp)
+{
+ struct ftrace_entries_info *info = filp->private_data;
+
+ kfree(info);
+
+ return 0;
+}
+
static ssize_t
tracing_total_entries_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
@@ -3779,7 +3886,7 @@
mutex_lock(&trace_types_lock);
for_each_tracing_cpu(cpu) {
- size += tr->entries >> 10;
+ size += tr->data[cpu]->entries >> 10;
if (!ring_buffer_expanded)
expanded_size += trace_buf_size >> 10;
}
@@ -3813,7 +3920,7 @@
if (trace_flags & TRACE_ITER_STOP_ON_FREE)
tracing_off();
/* resize the ring buffer to 0 */
- tracing_resize_ring_buffer(0);
+ tracing_resize_ring_buffer(0, RING_BUFFER_ALL_CPUS);
return 0;
}
@@ -4012,9 +4119,10 @@
};
static const struct file_operations tracing_entries_fops = {
- .open = tracing_open_generic,
+ .open = tracing_entries_open,
.read = tracing_entries_read,
.write = tracing_entries_write,
+ .release = tracing_entries_release,
.llseek = generic_file_llseek,
};
@@ -4466,6 +4574,9 @@
trace_create_file("stats", 0444, d_cpu,
(void *) cpu, &tracing_stats_fops);
+
+ trace_create_file("buffer_size_kb", 0444, d_cpu,
+ (void *) cpu, &tracing_entries_fops);
}
#ifdef CONFIG_FTRACE_SELFTEST
@@ -4795,7 +4906,7 @@
(void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
trace_create_file("buffer_size_kb", 0644, d_tracer,
- &global_trace, &tracing_entries_fops);
+ (void *) RING_BUFFER_ALL_CPUS, &tracing_entries_fops);
trace_create_file("buffer_total_size_kb", 0444, d_tracer,
&global_trace, &tracing_total_entries_fops);
@@ -5056,7 +5167,6 @@
WARN_ON(1);
goto out_free_cpumask;
}
- global_trace.entries = ring_buffer_size(global_trace.buffer);
if (global_trace.buffer_disabled)
tracing_off();
@@ -5069,7 +5179,6 @@
ring_buffer_free(global_trace.buffer);
goto out_free_cpumask;
}
- max_tr.entries = 1;
#endif
/* Allocate the first page for all buffers */
@@ -5078,6 +5187,11 @@
max_tr.data[i] = &per_cpu(max_tr_data, i);
}
+ set_buffer_entries(&global_trace, ring_buf_size);
+#ifdef CONFIG_TRACER_MAX_TRACE
+ set_buffer_entries(&max_tr, 1);
+#endif
+
trace_init_cmdlines();
register_tracer(&nop_trace);