sched: latencytop support

LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 6fa6cf036c70..55771fd7e545 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -33,6 +33,19 @@ static void save_stack_address(void *data, unsigned long addr)
                 trace->entries[trace->nr_entries++] = addr;
 }
 
+static void save_stack_address_nosched(void *data, unsigned long addr)
+{
+        struct stack_trace *trace = (struct stack_trace *)data;
+        if (in_sched_functions(addr))
+                return;
+        if (trace->skip > 0) {
+                trace->skip--;
+                return;
+        }
+        if (trace->nr_entries < trace->max_entries)
+                trace->entries[trace->nr_entries++] = addr;
+}
+
 static const struct stacktrace_ops save_stack_ops = {
         .warning = save_stack_warning,
         .warning_symbol = save_stack_warning_symbol,
@@ -40,6 +53,13 @@ static const struct stacktrace_ops save_stack_ops = {
         .address = save_stack_address,
 };
 
+static const struct stacktrace_ops save_stack_ops_nosched = {
+        .warning = save_stack_warning,
+        .warning_symbol = save_stack_warning_symbol,
+        .stack = save_stack_stack,
+        .address = save_stack_address_nosched,
+};
+
 /*
  * Save stack-backtrace addresses into a stack_trace buffer.
  */
@@ -50,3 +70,10 @@ void save_stack_trace(struct stack_trace *trace)
                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 EXPORT_SYMBOL(save_stack_trace);
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+        dump_trace(tsk, NULL, NULL, &save_stack_ops_nosched, trace);
+        if (trace->nr_entries < trace->max_entries)
+                trace->entries[trace->nr_entries++] = ULONG_MAX;
+}