[PATCH v4 1/4] trace: Add per_cpu ring buffer control files

From: Vaibhav Nagarnaik
Date: Tue Oct 11 2011 - 21:20:25 EST

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.

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@xxxxxxxxxx>
---
Changelog v4-v3:
* restructure code according to feedback.

include/linux/ring_buffer.h | 6 +-
kernel/trace/ring_buffer.c | 248 ++++++++++++++++++++++++-------------------
kernel/trace/trace.c | 191 ++++++++++++++++++++++++++-------
kernel/trace/trace.h | 2 +-
4 files changed, 297 insertions(+), 150 deletions(-)

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index 67be037..ad36702 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -96,9 +96,11 @@ __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *k
__ring_buffer_alloc((size), (flags), &__key); \
})

+#define RING_BUFFER_ALL_CPUS -1
+
void ring_buffer_free(struct ring_buffer *buffer);

-int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
+int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);

void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);

@@ -129,7 +131,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
int ring_buffer_iter_empty(struct ring_buffer_iter *iter);

-unsigned long ring_buffer_size(struct ring_buffer *buffer);
+unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);

void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
void ring_buffer_reset(struct ring_buffer *buffer);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index acf6b68..7b39b09 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -481,6 +481,7 @@ struct ring_buffer_per_cpu {
spinlock_t reader_lock; /* serialize readers */
arch_spinlock_t lock;
struct lock_class_key lock_key;
+ unsigned int nr_pages;
struct list_head *pages;
struct buffer_page *head_page; /* read from head */
struct buffer_page *tail_page; /* write to tail */
@@ -498,10 +499,12 @@ struct ring_buffer_per_cpu {
unsigned long read_bytes;
u64 write_stamp;
u64 read_stamp;
+ /* ring buffer pages to update, > 0 to add, < 0 to remove */
+ int nr_pages_to_update;
+ struct list_head new_pages; /* new pages to add */
};

struct ring_buffer {
- unsigned pages;
unsigned flags;
int cpus;
atomic_t record_disabled;
@@ -995,14 +998,10 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
return 0;
}

-static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
- unsigned nr_pages)
+static int __rb_allocate_pages(int nr_pages, struct list_head *pages, int cpu)
{
+ int i;
struct buffer_page *bpage, *tmp;
- LIST_HEAD(pages);
- unsigned i;
-
- WARN_ON(!nr_pages);

for (i = 0; i < nr_pages; i++) {
struct page *page;
@@ -1013,15 +1012,13 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
*/
bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
GFP_KERNEL | __GFP_NORETRY,
- cpu_to_node(cpu_buffer->cpu));
+ cpu_to_node(cpu));
if (!bpage)
goto free_pages;

- rb_check_bpage(cpu_buffer, bpage);
+ list_add(&bpage->list, pages);

- list_add(&bpage->list, &pages);
-
- page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu),
+ page = alloc_pages_node(cpu_to_node(cpu),
GFP_KERNEL | __GFP_NORETRY, 0);
if (!page)
goto free_pages;
@@ -1029,6 +1026,27 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
rb_init_page(bpage->page);
}

+ return 0;
+
+free_pages:
+ list_for_each_entry_safe(bpage, tmp, pages, list) {
+ list_del_init(&bpage->list);
+ free_buffer_page(bpage);
+ }
+
+ return -ENOMEM;
+}
+
+static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
+ unsigned nr_pages)
+{
+ LIST_HEAD(pages);
+
+ WARN_ON(!nr_pages);
+
+ if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu))
+ return -ENOMEM;
+
/*
* The ring buffer page list is a circular list that does not
* start and end with a list head. All page list items point to
@@ -1037,20 +1055,15 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
cpu_buffer->pages = pages.next;
list_del(&pages);

+ cpu_buffer->nr_pages = nr_pages;
+
rb_check_pages(cpu_buffer);

return 0;
-
- free_pages:
- list_for_each_entry_safe(bpage, tmp, &pages, list) {
- list_del_init(&bpage->list);
- free_buffer_page(bpage);
- }
- return -ENOMEM;
}

static struct ring_buffer_per_cpu *
-rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
+rb_allocate_cpu_buffer(struct ring_buffer *buffer, int nr_pages, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct buffer_page *bpage;
@@ -1084,7 +1097,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)

INIT_LIST_HEAD(&cpu_buffer->reader_page->list);

- ret = rb_allocate_pages(cpu_buffer, buffer->pages);
+ ret = rb_allocate_pages(cpu_buffer, nr_pages);
if (ret < 0)
goto fail_free_reader;

@@ -1145,7 +1158,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
{
struct ring_buffer *buffer;
int bsize;
- int cpu;
+ int cpu, nr_pages;

/* keep it in its own cache line */
buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()),
@@ -1156,14 +1169,14 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL))
goto fail_free_buffer;

- buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
+ nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
buffer->flags = flags;
buffer->clock = trace_clock_local;
buffer->reader_lock_key = key;

/* need at least two pages */
- if (buffer->pages < 2)
- buffer->pages = 2;
+ if (nr_pages < 2)
+ nr_pages = 2;

/*
* In case of non-hotplug cpu, if the ring-buffer is allocated
@@ -1186,7 +1199,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,

for_each_buffer_cpu(buffer, cpu) {
buffer->buffers[cpu] =
- rb_allocate_cpu_buffer(buffer, cpu);
+ rb_allocate_cpu_buffer(buffer, nr_pages, cpu);
if (!buffer->buffers[cpu])
goto fail_free_buffers;
}
@@ -1308,6 +1321,18 @@ out:
spin_unlock_irq(&cpu_buffer->reader_lock);
}

+static void update_pages_handler(struct ring_buffer_per_cpu *cpu_buffer)
+{
+ if (cpu_buffer->nr_pages_to_update > 0)
+ rb_insert_pages(cpu_buffer, &cpu_buffer->new_pages,
+ cpu_buffer->nr_pages_to_update);
+ else
+ rb_remove_pages(cpu_buffer, -cpu_buffer->nr_pages_to_update);
+ cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update;
+ /* reset this value */
+ cpu_buffer->nr_pages_to_update = 0;
+}
+
/**
* ring_buffer_resize - resize the ring buffer
* @buffer: the buffer to resize.
@@ -1317,14 +1342,12 @@ out:
*
* Returns -1 on failure.
*/
-int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
+int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
+ int cpu_id)
{
struct ring_buffer_per_cpu *cpu_buffer;
- unsigned nr_pages, rm_pages, new_pages;
- struct buffer_page *bpage, *tmp;
- unsigned long buffer_size;
- LIST_HEAD(pages);
- int i, cpu;
+ unsigned nr_pages;
+ int cpu;

/*
* Always succeed at resizing a non-existent buffer:
@@ -1334,15 +1357,11 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)

size = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
size *= BUF_PAGE_SIZE;
- buffer_size = buffer->pages * BUF_PAGE_SIZE;

/* we need a minimum of two pages */
if (size < BUF_PAGE_SIZE * 2)
size = BUF_PAGE_SIZE * 2;

- if (size == buffer_size)
- return size;
-
atomic_inc(&buffer->record_disabled);

/* Make sure all writers are done with this buffer. */
@@ -1353,68 +1372,56 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)

nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);

- if (size < buffer_size) {
-
- /* easy case, just free pages */
- if (RB_WARN_ON(buffer, nr_pages >= buffer->pages))
- goto out_fail;
-
- rm_pages = buffer->pages - nr_pages;
-
+ if (cpu_id == RING_BUFFER_ALL_CPUS) {
+ /* calculate the pages to update */
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
- rb_remove_pages(cpu_buffer, rm_pages);
- }
- goto out;
- }

- /*
- * This is a bit more difficult. We only want to add pages
- * when we can allocate enough for all CPUs. We do this
- * by allocating all the pages and storing them on a local
- * link list. If we succeed in our allocation, then we
- * add these pages to the cpu_buffers. Otherwise we just free
- * them all and return -ENOMEM;
- */
- if (RB_WARN_ON(buffer, nr_pages <= buffer->pages))
- goto out_fail;
+ cpu_buffer->nr_pages_to_update = nr_pages -
+ cpu_buffer->nr_pages;

- new_pages = nr_pages - buffer->pages;
+ /*
+ * nothing more to do for removing pages or no update
+ */
+ if (cpu_buffer->nr_pages_to_update <= 0)
+ continue;

- for_each_buffer_cpu(buffer, cpu) {
- for (i = 0; i < new_pages; i++) {
- struct page *page;
/*
- * __GFP_NORETRY flag makes sure that the allocation
- * fails gracefully without invoking oom-killer and
- * the system is not destabilized.
+ * to add pages, make sure all new pages can be
+ * allocated without receiving ENOMEM
*/
- bpage = kzalloc_node(ALIGN(sizeof(*bpage),
- cache_line_size()),
- GFP_KERNEL | __GFP_NORETRY,
- cpu_to_node(cpu));
- if (!bpage)
- goto free_pages;
- list_add(&bpage->list, &pages);
- page = alloc_pages_node(cpu_to_node(cpu),
- GFP_KERNEL | __GFP_NORETRY, 0);
- if (!page)
- goto free_pages;
- bpage->page = page_address(page);
- rb_init_page(bpage->page);
+ INIT_LIST_HEAD(&cpu_buffer->new_pages);
+ if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update,
+ &cpu_buffer->new_pages, cpu))
+ /* not enough memory for new pages */
+ goto no_mem;
}
- }

- for_each_buffer_cpu(buffer, cpu) {
- cpu_buffer = buffer->buffers[cpu];
- rb_insert_pages(cpu_buffer, &pages, new_pages);
- }
+ /* wait for all the updates to complete */
+ for_each_buffer_cpu(buffer, cpu) {
+ cpu_buffer = buffer->buffers[cpu];
+ if (cpu_buffer->nr_pages_to_update) {
+ update_pages_handler(cpu_buffer);
+ }
+ }
+ } else {
+ cpu_buffer = buffer->buffers[cpu_id];
+ if (nr_pages == cpu_buffer->nr_pages)
+ goto out;

- if (RB_WARN_ON(buffer, !list_empty(&pages)))
- goto out_fail;
+ cpu_buffer->nr_pages_to_update = nr_pages -
+ cpu_buffer->nr_pages;
+
+ INIT_LIST_HEAD(&cpu_buffer->new_pages);
+ if (cpu_buffer->nr_pages_to_update > 0 &&
+ __rb_allocate_pages(cpu_buffer->nr_pages_to_update,
+ &cpu_buffer->new_pages, cpu_id))
+ goto no_mem;
+
+ update_pages_handler(cpu_buffer);
+ }

out:
- buffer->pages = nr_pages;
put_online_cpus();
mutex_unlock(&buffer->mutex);

@@ -1422,25 +1429,24 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)

return size;

- free_pages:
- list_for_each_entry_safe(bpage, tmp, &pages, list) {
- list_del_init(&bpage->list);
- free_buffer_page(bpage);
+ no_mem:
+ for_each_buffer_cpu(buffer, cpu) {
+ struct buffer_page *bpage, *tmp;
+ cpu_buffer = buffer->buffers[cpu];
+ /* reset this number regardless */
+ cpu_buffer->nr_pages_to_update = 0;
+ if (list_empty(&cpu_buffer->new_pages))
+ continue;
+ list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages,
+ list) {
+ list_del_init(&bpage->list);
+ free_buffer_page(bpage);
+ }
}
put_online_cpus();
mutex_unlock(&buffer->mutex);
atomic_dec(&buffer->record_disabled);
return -ENOMEM;
-
- /*
- * Something went totally wrong, and we are too paranoid
- * to even clean up the mess.
- */
- out_fail:
- put_online_cpus();
- mutex_unlock(&buffer->mutex);
- atomic_dec(&buffer->record_disabled);
- return -1;
}
EXPORT_SYMBOL_GPL(ring_buffer_resize);

@@ -1542,7 +1548,7 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer)
* assign the commit to the tail.
*/
again:
- max_count = cpu_buffer->buffer->pages * 100;
+ max_count = cpu_buffer->nr_pages * 100;

while (cpu_buffer->commit_page != cpu_buffer->tail_page) {
if (RB_WARN_ON(cpu_buffer, !(--max_count)))
@@ -3563,9 +3569,18 @@ EXPORT_SYMBOL_GPL(ring_buffer_read);
* ring_buffer_size - return the size of the ring buffer (in bytes)
* @buffer: The ring buffer.
*/
-unsigned long ring_buffer_size(struct ring_buffer *buffer)
+unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu)
{
- return BUF_PAGE_SIZE * buffer->pages;
+ /*
+ * Earlier, this method returned
+ * BUF_PAGE_SIZE * buffer->nr_pages
+ * Since the nr_pages field is now removed, we have converted this to
+ * return the per cpu buffer value.
+ */
+ if (!cpumask_test_cpu(cpu, buffer->cpumask))
+ return 0;
+
+ return BUF_PAGE_SIZE * buffer->buffers[cpu]->nr_pages;
}
EXPORT_SYMBOL_GPL(ring_buffer_size);

@@ -3740,8 +3755,11 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
!cpumask_test_cpu(cpu, buffer_b->cpumask))
goto out;

+ cpu_buffer_a = buffer_a->buffers[cpu];
+ cpu_buffer_b = buffer_b->buffers[cpu];
+
/* At least make sure the two buffers are somewhat the same */
- if (buffer_a->pages != buffer_b->pages)
+ if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages)
goto out;

ret = -EAGAIN;
@@ -3755,9 +3773,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
if (atomic_read(&buffer_b->record_disabled))
goto out;

- cpu_buffer_a = buffer_a->buffers[cpu];
- cpu_buffer_b = buffer_b->buffers[cpu];
-
if (atomic_read(&cpu_buffer_a->record_disabled))
goto out;

@@ -4108,6 +4123,8 @@ static int rb_cpu_notify(struct notifier_block *self,
struct ring_buffer *buffer =
container_of(self, struct ring_buffer, cpu_notify);
long cpu = (long)hcpu;
+ int cpu_i, nr_pages_same;
+ unsigned int nr_pages;

switch (action) {
case CPU_UP_PREPARE:
@@ -4115,8 +4132,23 @@ static int rb_cpu_notify(struct notifier_block *self,
if (cpumask_test_cpu(cpu, buffer->cpumask))
return NOTIFY_OK;

+ nr_pages = 0;
+ nr_pages_same = 1;
+ /* check if all cpu sizes are same */
+ for_each_buffer_cpu(buffer, cpu_i) {
+ /* fill in the size from first enabled cpu */
+ if (nr_pages == 0)
+ nr_pages = buffer->buffers[cpu_i]->nr_pages;
+ if (nr_pages != buffer->buffers[cpu_i]->nr_pages) {
+ nr_pages_same = 0;
+ break;
+ }
+ }
+ /* allocate minimum pages, user can later expand it */
+ if (!nr_pages_same)
+ nr_pages = 2;
buffer->buffers[cpu] =
- rb_allocate_cpu_buffer(buffer, cpu);
+ rb_allocate_cpu_buffer(buffer, nr_pages, cpu);
if (!buffer->buffers[cpu]) {
WARN(1, "failed to allocate ring buffer on CPU %ld\n",
cpu);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b419070..bb3c867 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -784,7 +784,8 @@ __acquires(kernel_lock)

/* 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);
@@ -800,7 +801,8 @@ __acquires(kernel_lock)

/* 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");
}
@@ -2853,7 +2855,14 @@ int tracer_init(struct tracer *t, struct trace_array *tr)
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;

@@ -2864,19 +2873,32 @@ static int __tracing_resize_ring_buffer(unsigned long size)
*/
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;
+
+ 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);
+ }

- r = ring_buffer_resize(global_trace.buffer,
- global_trace.entries);
if (r < 0) {
/*
* AARGH! We are left with different
@@ -2898,14 +2920,21 @@ static int __tracing_resize_ring_buffer(unsigned long size)
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;

@@ -2921,12 +2950,19 @@ static ssize_t tracing_resize_ring_buffer(unsigned long size)
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);
@@ -2957,7 +2993,8 @@ int tracing_update_buffers(void)

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;
@@ -2981,7 +3018,8 @@ static int tracing_set_tracer(const char *buf)
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;
@@ -3007,8 +3045,8 @@ static int tracing_set_tracer(const char *buf)
* 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);

@@ -3016,10 +3054,17 @@ static int tracing_set_tracer(const char *buf)

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) {
@@ -3521,30 +3566,82 @@ out_err:
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;

@@ -3559,7 +3656,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
/* 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;

@@ -3568,6 +3665,16 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
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)
@@ -3579,7 +3686,7 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf,

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;
}
@@ -3613,7 +3720,7 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
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;
}
@@ -3757,9 +3864,10 @@ static const struct file_operations tracing_pipe_fops = {
};

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,
};

@@ -4211,6 +4319,9 @@ static void tracing_init_debugfs_percpu(long cpu)

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
@@ -4491,7 +4602,7 @@ static __init int tracer_init_debugfs(void)
(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);
@@ -4737,8 +4848,6 @@ __init static int tracer_alloc_buffers(void)
WARN_ON(1);
goto out_free_cpumask;
}
- global_trace.entries = ring_buffer_size(global_trace.buffer);
-

#ifdef CONFIG_TRACER_MAX_TRACE
max_tr.buffer = ring_buffer_alloc(1, rb_flags);
@@ -4748,7 +4857,6 @@ __init static int tracer_alloc_buffers(void)
ring_buffer_free(global_trace.buffer);
goto out_free_cpumask;
}
- max_tr.entries = 1;
#endif

/* Allocate the first page for all buffers */
@@ -4757,6 +4865,11 @@ __init static int tracer_alloc_buffers(void)
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);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 616846b..126d333 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -125,6 +125,7 @@ struct trace_array_cpu {
atomic_t disabled;
void *buffer_page; /* ring buffer spare */

+ unsigned long entries;
unsigned long saved_latency;
unsigned long critical_start;
unsigned long critical_end;
@@ -146,7 +147,6 @@ struct trace_array_cpu {
*/
struct trace_array {
struct ring_buffer *buffer;
- unsigned long entries;
int cpu;
cycle_t time_start;
struct task_struct *waiter;
--
1.7.3.1

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