diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2009-03-11 14:33:00 -0400 |
|---|---|---|
| committer | Steven Rostedt <srostedt@redhat.com> | 2009-03-11 22:15:24 -0400 |
| commit | 1852fcce181faa237c010a3dbedb473cf9d4555f (patch) | |
| tree | 863cd12b573fd36436e7fb042f9bd96a73a9f725 /kernel/trace | |
| parent | 73c5162aa362a543793f4a957c6c536dcbaa89ce (diff) | |
tracing: expand the ring buffers when an event is activated
To save memory, the tracer ring buffers are set to a minimum.
The activating of a trace expands the ring buffer size. This patch
adds this expanding, when an event is activated.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 20 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 3 | ||||
| -rw-r--r-- | kernel/trace/trace_events.c | 8 |
3 files changed, 31 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0c1dc185085..35ee63ae412 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2357,6 +2357,26 @@ static int tracing_resize_ring_buffer(unsigned long size) return ret; } +/** + * tracing_update_buffers - used by tracing facility to expand ring buffers + * + * To save on memory when the tracing is never used on a system with it + * configured in. The ring buffers are set to a minimum size. But once + * a user starts to use the tracing facility, then they need to grow + * to their default size. + * + * This function is to be called when a tracer is about to be used. + */ +int tracing_update_buffers(void) +{ + int ret = 0; + + if (!ring_buffer_expanded) + ret = tracing_resize_ring_buffer(trace_buf_size); + + return ret; +} + struct trace_option_dentry; static struct trace_option_dentry * diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index c5e1d8865fe..336324d717f 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -737,6 +737,9 @@ static inline void trace_branch_disable(void) } #endif /* CONFIG_BRANCH_TRACER */ +/* set ring buffers to default size if not already done so */ +int tracing_update_buffers(void); + /* trace event type bit fields, not numeric */ enum { TRACE_EVENT_TYPE_PRINTF = 1, diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 769dfd00fc8..ca624df7359 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -141,6 +141,10 @@ ftrace_event_write(struct file *file, const char __user *ubuf, if (!cnt || cnt < 0) return 0; + ret = tracing_update_buffers(); + if (ret < 0) + return ret; + ret = get_user(ch, ubuf++); if (ret) return ret; @@ -331,6 +335,10 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, if (ret < 0) return ret; + ret = tracing_update_buffers(); + if (ret < 0) + return ret; + switch (val) { case 0: case 1: |