move all projects into the trunk directory

[lttv.git] / ltt / branches / poly / doc / developer / markers-update.txt

diff --git a/ltt/branches/poly/doc/developer/markers-update.txt b/ltt/branches/poly/doc/developer/markers-update.txt
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@@ -1,116 +0,0 @@
-
-Tracepoint proposal
-
-- Tracepoint infrastructure
-  - In-kernel users
-  - Complete typing, verified by the compiler
-  - Dynamically linked and activated
-
-- Marker infrastructure
-  - Exported API to userland
-  - Basic types only
-
-- Dynamic vs static
-  - In-kernel probes are dynamically linked, dynamically activated, connected to
-    tracepoints. Type verification is done at compile-time. Those in-kernel
-    probes can be a probe extracting the information to put in a marker or a
-    specific in-kernel tracer such as ftrace.
-  - Information sinks (LTTng, SystemTAP) are dynamically connected to the
-    markers inserted in the probes and are dynamically activated.
-
-- Near instrumentation site vs in a separate tracer module
-
-A probe module, only if provided with the kernel tree, could connect to internal
-tracing sites. This argues for keeping the tracepoing probes near the
-instrumentation site code. However, if a tracer is general purpose and exports
-typing information to userspace through some mechanism, it should only export
-the "basic type" information and could be therefore shipped outside of the
-kernel tree.
-
-In-kernel probes should be integrated to the kernel tree. They would be close to
-the instrumented kernel code and would translate between the in-kernel
-instrumentation and the "basic type" exports. Other in-kernel probes could
-provide a different output (statistics available through debugfs for instance).
-ftrace falls into this category.
-
-Generic or specialized information "sinks" (LTTng, systemtap) could be connected
-to the markers put in tracepoint probes to extract the information to userspace.
-They would extract both typing information and the per-tracepoint execution
-information to userspace.
-
-Therefore, the code would look like :
-
-kernel/sched.c:
-
-#include "sched-trace.h"
-
-schedule()
-{
-  ...
-  trace_sched_switch(prev, next);
-  ...
-}
-
-
-kernel/sched-trace.h:
-
-DEFINE_TRACE(sched_switch, struct task_struct *prev, struct task_struct *next);
-
-
-kernel/sched-trace.c:
-
-#include "sched-trace.h"
-
-static probe_sched_switch(struct task_struct *prev, struct task_struct
-  *next)
-{
-  trace_mark(kernel_sched_switch, "prev_pid %d next_pid %d prev_state %ld",
-    prev->pid, next->pid, prev->state);
-}
-
-int __init init(void)
-{
-  return register_sched_switch(probe_sched_switch);
-}
-
-void __exit exit(void)
-{
-  unregister_sched_switch(probe_sched_switch);
-}
-
-
-Where DEFINE_TRACE internals declare a structure, a trace_* inline function,
-a register_trace_* and unregister_trace_* inline functions :
-
-static instrumentation site structure, containing function pointers to
-deactivated functions and activation boolean. It also contains the
-"sched_switch" string. This structure is placed in a special section to create
-an array of these structures.
-
-static inline void trace_sched_switch(struct task_struct *prev,
-  struct task_struct *next)
-{
- if (sched_switch tracing is activated)
-   marshall_probes(&instrumentation_site_structure, prev, next);
-}
-
-static inline int register_trace_sched_switch(
-  void (*probe)(struct task_struct *prev, struct task_struct *next)
-{
-  return do_register_probe("sched_switch", (void *)probe);
-}
-
-static inline void unregister_trace_sched_switch(
-  void (*probe)(struct task_struct *prev, struct task_struct *next)
-{
-  do_unregister_probe("sched_switch", (void *)probe);
-}
-
-
-We need a a new kernel probe API :
-
-do_register_probe / do_unregister_probe
-  - Connects the in-kernel probe to the site
-  - Activates the site tracing (probe reference counting)
-
-