This displays the total combined size of all the trace buffers.
- buffer_subbuf_order:
-
- This sets or displays the sub buffer page size order. The ring buffer
- is broken up into several same size "sub buffers". An event can not be
- bigger than the size of the sub buffer. Normally, the sub buffer is
- the size of the architecture's page (4K on x86). The sub buffer also
- contains meta data at the start which also limits the size of an event.
- That means when the sub buffer is a page size, no event can be larger
- than the page size minus the sub buffer meta data.
-
- The buffer_subbuf_order allows the user to change the size of the sub
- buffer. As the sub buffer is a set of pages by the power of 2, thus
- the sub buffer total size is defined by the order:
-
- order size
- ---- ----
- 0 PAGE_SIZE
- 1 PAGE_SIZE * 2
- 2 PAGE_SIZE * 4
- 3 PAGE_SIZE * 8
-
- Changing the order will change the sub buffer size allowing for events
- to be larger than the page size.
-
- Note: When changing the order, tracing is stopped and any data in the
- ring buffer and the snapshot buffer will be discarded.
+ buffer_subbuf_size_kb:
+
+ This sets or displays the sub buffer size. The ring buffer is broken up
+ into several same size "sub buffers". An event can not be bigger than
+ the size of the sub buffer. Normally, the sub buffer is the size of the
+ architecture's page (4K on x86). The sub buffer also contains meta data
+ at the start which also limits the size of an event. That means when
+ the sub buffer is a page size, no event can be larger than the page
+ size minus the sub buffer meta data.
+
+ Note, the buffer_subbuf_size_kb is a way for the user to specify the
+ minimum size of the subbuffer. The kernel may make it bigger due to the
+ implementation details, or simply fail the operation if the kernel can
+ not handle the request.
+
+ Changing the sub buffer size allows for events to be larger than the
+ page size.
+
+ Note: When changing the sub-buffer size, tracing is stopped and any
+ data in the ring buffer and the snapshot buffer will be discarded.
free_buffer:
};
static ssize_t
-buffer_order_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+buffer_subbuf_size_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
+ size_t size;
char buf[64];
+ int order;
int r;
- r = sprintf(buf, "%d\n", ring_buffer_subbuf_order_get(tr->array_buffer.buffer));
+ order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer);
+ size = (PAGE_SIZE << order) / 1024;
+
+ r = sprintf(buf, "%zd\n", size);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
-buffer_order_write(struct file *filp, const char __user *ubuf,
- size_t cnt, loff_t *ppos)
+buffer_subbuf_size_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
unsigned long val;
int old_order;
+ int order;
+ int pages;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
+ val *= 1024; /* value passed in is in KB */
+
+ pages = DIV_ROUND_UP(val, PAGE_SIZE);
+ order = fls(pages - 1);
+
/* limit between 1 and 128 system pages */
- if (val < 0 || val > 7)
+ if (order < 0 || order > 7)
return -EINVAL;
/* Do not allow tracing while changing the order of the ring buffer */
tracing_stop_tr(tr);
old_order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer);
- if (old_order == val)
+ if (old_order == order)
goto out;
- ret = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, val);
+ ret = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, order);
if (ret)
goto out;
if (!tr->allocated_snapshot)
goto out_max;
- ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, val);
+ ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order);
if (ret) {
/* Put back the old order */
cnt = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, old_order);
return cnt;
}
-static const struct file_operations buffer_order_fops = {
+static const struct file_operations buffer_subbuf_size_fops = {
.open = tracing_open_generic_tr,
- .read = buffer_order_read,
- .write = buffer_order_write,
+ .read = buffer_subbuf_size_read,
+ .write = buffer_subbuf_size_write,
.release = tracing_release_generic_tr,
.llseek = default_llseek,
};
trace_create_file("buffer_percent", TRACE_MODE_WRITE, d_tracer,
tr, &buffer_percent_fops);
- trace_create_file("buffer_subbuf_order", TRACE_MODE_WRITE, d_tracer,
- tr, &buffer_order_fops);
+ trace_create_file("buffer_subbuf_size_kb", TRACE_MODE_WRITE, d_tracer,
+ tr, &buffer_subbuf_size_fops);
create_trace_options_dir(tr);
+++ /dev/null
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
-# description: Change the ringbuffer sub-buffer order
-# requires: buffer_subbuf_order
-# flags: instance
-
-get_buffer_data_size() {
- sed -ne 's/^.*data.*size:\([0-9][0-9]*\).*/\1/p' events/header_page
-}
-
-get_buffer_data_offset() {
- sed -ne 's/^.*data.*offset:\([0-9][0-9]*\).*/\1/p' events/header_page
-}
-
-get_event_header_size() {
- type_len=`sed -ne 's/^.*type_len.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
- time_len=`sed -ne 's/^.*time_delta.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
- array_len=`sed -ne 's/^.*array.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
- total_bits=$((type_len+time_len+array_len))
- total_bits=$((total_bits+7))
- echo $((total_bits/8))
-}
-
-get_print_event_buf_offset() {
- sed -ne 's/^.*buf.*offset:\([0-9][0-9]*\).*/\1/p' events/ftrace/print/format
-}
-
-event_header_size=`get_event_header_size`
-print_header_size=`get_print_event_buf_offset`
-
-data_offset=`get_buffer_data_offset`
-
-marker_meta=$((event_header_size+print_header_size))
-
-make_str() {
- cnt=$1
- printf -- 'X%.0s' $(seq $cnt)
-}
-
-write_buffer() {
- size=$1
-
- str=`make_str $size`
-
- # clear the buffer
- echo > trace
-
- # write the string into the marker
- echo $str > trace_marker
-
- echo $str
-}
-
-test_buffer() {
- orde=$1
- page_size=$((4096<<order))
-
- size=`get_buffer_data_size`
-
- # the size must be greater than or equal to page_size - data_offset
- page_size=$((page_size-data_offset))
- if [ $size -lt $page_size ]; then
- exit fail
- fi
-
- # Now add a little more the meta data overhead will overflow
-
- str=`write_buffer $size`
-
- # Make sure the line was broken
- new_str=`awk ' /tracing_mark_write:/ { sub(/^.*tracing_mark_write: /,"");printf "%s", $0; exit}' trace`
-
- if [ "$new_str" = "$str" ]; then
- exit fail;
- fi
-
- # Make sure the entire line can be found
- new_str=`awk ' /tracing_mark_write:/ { sub(/^.*tracing_mark_write: /,"");printf "%s", $0; }' trace`
-
- if [ "$new_str" != "$str" ]; then
- exit fail;
- fi
-}
-
-ORIG=`cat buffer_subbuf_order`
-
-# Could test bigger orders than 3, but then creating the string
-# to write into the ring buffer takes too long
-for a in 0 1 2 3 ; do
- echo $a > buffer_subbuf_order
- test_buffer $a
-done
-
-echo $ORIG > buffer_subbuf_order
-
--- /dev/null
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Change the ringbuffer sub-buffer size
+# requires: buffer_subbuf_size_kb
+# flags: instance
+
+get_buffer_data_size() {
+ sed -ne 's/^.*data.*size:\([0-9][0-9]*\).*/\1/p' events/header_page
+}
+
+get_buffer_data_offset() {
+ sed -ne 's/^.*data.*offset:\([0-9][0-9]*\).*/\1/p' events/header_page
+}
+
+get_event_header_size() {
+ type_len=`sed -ne 's/^.*type_len.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
+ time_len=`sed -ne 's/^.*time_delta.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
+ array_len=`sed -ne 's/^.*array.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
+ total_bits=$((type_len+time_len+array_len))
+ total_bits=$((total_bits+7))
+ echo $((total_bits/8))
+}
+
+get_print_event_buf_offset() {
+ sed -ne 's/^.*buf.*offset:\([0-9][0-9]*\).*/\1/p' events/ftrace/print/format
+}
+
+event_header_size=`get_event_header_size`
+print_header_size=`get_print_event_buf_offset`
+
+data_offset=`get_buffer_data_offset`
+
+marker_meta=$((event_header_size+print_header_size))
+
+make_str() {
+ cnt=$1
+ printf -- 'X%.0s' $(seq $cnt)
+}
+
+write_buffer() {
+ size=$1
+
+ str=`make_str $size`
+
+ # clear the buffer
+ echo > trace
+
+ # write the string into the marker
+ echo $str > trace_marker
+
+ echo $str
+}
+
+test_buffer() {
+ size_kb=$1
+ page_size=$((size_kb*1024))
+
+ size=`get_buffer_data_size`
+
+ # the size must be greater than or equal to page_size - data_offset
+ page_size=$((page_size-data_offset))
+ if [ $size -lt $page_size ]; then
+ exit fail
+ fi
+
+ # Now add a little more the meta data overhead will overflow
+
+ str=`write_buffer $size`
+
+ # Make sure the line was broken
+ new_str=`awk ' /tracing_mark_write:/ { sub(/^.*tracing_mark_write: /,"");printf "%s", $0; exit}' trace`
+
+ if [ "$new_str" = "$str" ]; then
+ exit fail;
+ fi
+
+ # Make sure the entire line can be found
+ new_str=`awk ' /tracing_mark_write:/ { sub(/^.*tracing_mark_write: /,"");printf "%s", $0; }' trace`
+
+ if [ "$new_str" != "$str" ]; then
+ exit fail;
+ fi
+}
+
+ORIG=`cat buffer_subbuf_size_kb`
+
+# Could test bigger sizes than 32K, but then creating the string
+# to write into the ring buffer takes too long
+for a in 4 8 16 32 ; do
+ echo $a > buffer_subbuf_size_kb
+ test_buffer $a
+done
+
+echo $ORIG > buffer_subbuf_size_kb
+
projects / linux-2.6-block.git / commitdiff