tracing: Add snapshot feature to instances (ce9bae55) · Commits · 戴 / test

Add the "snapshot" file to the the multi-buffer instances. cd /sys/kernel/debug/tracing/instances mkdir foo ls foo buffer_size_kb buffer_total_size_kb events free_buffer set_event snapshot trace trace_clock trace_marker trace_options trace_pipe tracing_on cat foo/snapshot # tracer: nop # # # * Snapshot is freed * # # Snapshot commands: # echo 0 > snapshot : Clears and frees snapshot buffer # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated. # Takes a snapshot of the main buffer. # echo 2 > snapshot : Clears snapshot buffer (but does not allocate) # (Doesn't have to be '2' works with any number that # is not a '0' or '1') Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -4302,9 +4302,9 @@ tracing_snapshot_write(struct file filp, const char __user ubuf, size_t cnt,
		local_irq_disable();
		/* Now, we're going to swap */
		if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
		update_max_tr(&global_trace, current, smp_processor_id());
		update_max_tr(tr, current, smp_processor_id());
		else
		update_max_tr_single(&global_trace, current, iter->cpu_file);
		update_max_tr_single(tr, current, iter->cpu_file);
		local_irq_enable();
		break;
		default:
		@@ -5533,6 +5533,11 @@ init_tracer_debugfs(struct trace_array tr, struct dentry d_tracer)

		trace_create_file("tracing_on", 0644, d_tracer,
		tr, &rb_simple_fops);

		#ifdef CONFIG_TRACER_SNAPSHOT
		trace_create_file("snapshot", 0644, d_tracer,
		(void *)&tr->trace_cpu, &snapshot_fops);
		#endif
		}

		static __init int tracer_init_debugfs(void)
		@@ -5574,11 +5579,6 @@ static __init int tracer_init_debugfs(void)
		&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
		#endif

		#ifdef CONFIG_TRACER_SNAPSHOT
		trace_create_file("snapshot", 0644, d_tracer,
		(void *)&global_trace.trace_cpu, &snapshot_fops);
		#endif

		create_trace_instances(d_tracer);

		create_trace_options_dir(&global_trace);

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