LTT for 2.5.36 2/9: Trace driver

diff -urpN linux-2.5.36/drivers/Makefile linux-2.5.36-ltt/drivers/Makefile
@@ -41,5 +41,6 @@ obj-$(CONFIG_MD)		+= md/
 obj-$(CONFIG_BLUEZ)		+= bluetooth/
 obj-$(CONFIG_HOTPLUG_PCI)	+= hotplug/
 obj-$(CONFIG_ISDN_BOOL)		+= isdn/
+obj-$(CONFIG_TRACE)		+= trace/
 
 include $(TOPDIR)/Rules.make

diff -urpN linux-2.5.36/drivers/trace/Config.help linux-2.5.36-ltt/drivers/trace/Config.help
@@ -0,0 +1,36 @@
+Kernel events tracing support
+CONFIG_TRACE
+  It is possible for the kernel to log important events to a tracing
+  driver. Doing so, enables the use of the generated traces in order
+  to reconstruct the dynamic behavior of the kernel, and hence the
+  whole system.
+
+  The tracing process contains 4 parts :
+      1) The logging of events by key parts of the kernel.
+      2) The trace driver that keeps the events in a data buffer.
+      3) A trace daemon that opens the trace driver and is notified
+         every time there is a certain quantity of data to read
+         from the trace driver (using SIG_IO).
+      4) A trace event data decoder that reads the accumulated data
+         and formats it in a human-readable format.
+
+  If you say Y or M here, the first part of the tracing process will
+  always take place. That is, critical parts of the kernel will call
+  upon the kernel tracing function. The data generated doesn't go
+  any further until a trace driver registers himself as such with the
+  kernel. Therefore, if you answer Y, then the driver will be part of
+  the kernel and the events will always proceed onto the driver and
+  if you say M, then the events will only proceed onto the driver when
+  it's module is loaded. Note that event's aren't logged in the driver
+  until the profiling daemon opens the device, configures it and
+  issues the "start" command through ioctl().
+
+  The impact of a fully functionnal system (kernel event logging +
+  driver event copying + active trace daemon) is of 2.5% for core events.
+  This means that for a task that took 100 seconds on a normal system, it
+  will take 102.5 seconds on a traced system. This is very low compared
+  to other profiling or tracing methods.
+
+  For more information on kernel tracing, the trace daemon or the event
+  decoder, please check the following address :
+       http://www.opersys.com/LTT

diff -urpN linux-2.5.36/drivers/trace/Config.in linux-2.5.36-ltt/drivers/trace/Config.in
@@ -0,0 +1,4 @@
+mainmenu_option next_comment
+comment 'Kernel tracing'
+tristate 'Kernel events tracing support' CONFIG_TRACE
+endmenu

diff -urpN linux-2.5.36/drivers/trace/Makefile linux-2.5.36-ltt/drivers/trace/Makefile
@@ -0,0 +1,17 @@
+#
+# Makefile for the kernel tracing drivers.
+#
+# Note! Dependencies are done automagically by 'make dep', which also
+# removes any old dependencies. DON'T put your own dependencies here
+# unless it's something special (ie not a .c file).
+#
+# Note 2! The CFLAGS definitions are now inherited from the
+# parent makes..
+#
+
+O_TARGET := built-in.o
+
+# Is it loaded as a module or as part of the kernel
+obj-$(CONFIG_TRACE) = tracer.o
+
+include $(TOPDIR)/Rules.make