diff options
| -rw-r--r-- | Documentation/trace/ftrace.txt | 5 | ||||
| -rw-r--r-- | include/linux/ring_buffer.h | 2 | ||||
| -rw-r--r-- | kernel/trace/ring_buffer.c | 11 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 17 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 1 |
5 files changed, 30 insertions, 6 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 67f1cc473257..1ebc24cf9a55 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -454,6 +454,11 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6] latencies, as described in "Latency trace format". + overwrite - This controls what happens when the trace buffer is + full. If "1" (default), the oldest events are + discarded and overwritten. If "0", then the newest + events are discarded. + ftrace_enabled -------------- diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 8d3a2486544d..ab38ac80b0f9 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -100,6 +100,8 @@ void ring_buffer_free(struct ring_buffer *buffer); int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size); +void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val); + struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length); int ring_buffer_unlock_commit(struct ring_buffer *buffer, diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index bd1c35a4fbcc..269db80a961e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1429,6 +1429,17 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) } EXPORT_SYMBOL_GPL(ring_buffer_resize); +void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) +{ + mutex_lock(&buffer->mutex); + if (val) + buffer->flags |= RB_FL_OVERWRITE; + else + buffer->flags &= ~RB_FL_OVERWRITE; + mutex_unlock(&buffer->mutex); +} +EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); + static inline void * __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) { diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8dc8da6733f9..85e3ee1e474e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -41,8 +41,6 @@ #include "trace.h" #include "trace_output.h" -#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE) - /* * On boot up, the ring buffer is set to the minimum size, so that * we do not waste memory on systems that are not using tracing. @@ -340,7 +338,7 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait); /* trace_flags holds trace_options default values */ unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK | TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME | - TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD; + TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE; static int trace_stop_count; static DEFINE_SPINLOCK(tracing_start_lock); @@ -425,6 +423,7 @@ static const char *trace_options[] = { "sleep-time", "graph-time", "record-cmd", + "overwrite", NULL }; @@ -2529,6 +2528,9 @@ static void set_tracer_flags(unsigned int mask, int enabled) if (mask == TRACE_ITER_RECORD_CMD) trace_event_enable_cmd_record(enabled); + + if (mask == TRACE_ITER_OVERWRITE) + ring_buffer_change_overwrite(global_trace.buffer, enabled); } static ssize_t @@ -4555,9 +4557,11 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) __init static int tracer_alloc_buffers(void) { int ring_buf_size; + enum ring_buffer_flags rb_flags; int i; int ret = -ENOMEM; + if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL)) goto out; @@ -4570,12 +4574,13 @@ __init static int tracer_alloc_buffers(void) else ring_buf_size = 1; + rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0; + cpumask_copy(tracing_buffer_mask, cpu_possible_mask); cpumask_copy(tracing_cpumask, cpu_all_mask); /* TODO: make the number of buffers hot pluggable with CPUS */ - global_trace.buffer = ring_buffer_alloc(ring_buf_size, - TRACE_BUFFER_FLAGS); + global_trace.buffer = ring_buffer_alloc(ring_buf_size, rb_flags); if (!global_trace.buffer) { printk(KERN_ERR "tracer: failed to allocate ring buffer!\n"); WARN_ON(1); @@ -4585,7 +4590,7 @@ __init static int tracer_alloc_buffers(void) #ifdef CONFIG_TRACER_MAX_TRACE - max_tr.buffer = ring_buffer_alloc(1, TRACE_BUFFER_FLAGS); + max_tr.buffer = ring_buffer_alloc(1, rb_flags); if (!max_tr.buffer) { printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n"); WARN_ON(1); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 856e73cc1d3f..951d0b7e7062 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -606,6 +606,7 @@ enum trace_iterator_flags { TRACE_ITER_SLEEP_TIME = 0x40000, TRACE_ITER_GRAPH_TIME = 0x80000, TRACE_ITER_RECORD_CMD = 0x100000, + TRACE_ITER_OVERWRITE = 0x200000, }; /* |