From db526ca329f855510e8ce672332eba3304aed590 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 12 Mar 2009 13:53:25 -0400 Subject: [PATCH] tracing: show that buffer size is not expanded Impact: do not confuse user on small trace buffer sizes When the system boots up, the trace buffer is small to conserve memory. It is only two pages per online CPU. When the tracer is used, it expands to the default value. This can confuse the user if they look at the buffer size and see only 7, but then later they see 1408. # cat /debug/tracing/buffer_size_kb 7 # echo sched_switch > /debug/tracing/current_tracer # cat /debug/tracing/buffer_size_kb 1408 This patch tries to help remove this confustion by showing that the buffer has not been expanded. # cat /debug/tracing/buffer_size_kb 7 (expanded: 1408) Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 04ab8243a13d..62a63b2b33dd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2948,10 +2948,18 @@ tracing_entries_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { struct trace_array *tr = filp->private_data; - char buf[64]; + char buf[96]; int r; - r = sprintf(buf, "%lu\n", tr->entries >> 10); + 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); + mutex_unlock(&trace_types_lock); + return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); }