[ltt-dev] Updated TODO list before releasing LTTng buffering to LKML

[zhaolei@cn.fujitsu.com (Zhaolei)]

> Hi everyone,
> 
> Thanks for the steady work those past weeks. We are close to a
> releasable result. I have been delighted to see people from Fujitsu
> helping on various items in the past weeks. Thanks to all those who
> report issues and/or provide patches.
> 
> Here is an updated Todo list before posting LTTng-buffering to LKML
> 
> Timestamping :
> 
> - Use kernel/time/tsc-sync.c in MIPS to detect unsync TSCs.
> - Tweak kernel/time/tsc-sync.c so it supports sync detection between two
>  CPUs so it can be used to replace arch/x86/kernel/tsc_sync.c
> - I plan to leave the current cache-line bouncing time source for CPUs
>  which have unsynched TSC, but to printk a warning telling the user to
>  disabled freq. scaling and halt in idle to make sure the clocks are
>  synchronized if he expects precise timestamping and good scalability
>  to large number of nodes. Let's keep room for improvement on this
>  aspect for later.
> 
> 
> Markers :
> 
> - Tie the markers to event IDs and buffer name. That will permit to
>  simplify a lot of stuff currently in ltt-marker-control.ko. It will
>  also remove the need for a global event ID assignation, making it
>  per-buffer (in LTTng terminology : per-channel).
>  (will be done by myself soon)
> 
> - move ltt/ltt-marker-control.c /proc interface to debugfs
>  I think we should integrate its directory tree to the new LTTng tracer
>  debugfs API like this :
> 
>  /debugfs/ltt/events/buffer_name/marker_name/
>    where we find files like :
>    state
>      write : 1/0 (on/off)
>      read  : 1/0 (on/off)
>    format
>      read : marker format string
Hello, Mathieu,

So we need to create a marker's debugfs-directory when user insmod
 a module with markers.
But i think we don't have a callback when user insmod, and we
 should avoid to patch kernel/module.c for this kind of function.

So, maybe we can only "echo marker_name 0/1" > marker-control.
Dou you have suggestion for me?

> 
>  (being done by Fujistsu)
> 
> 
> LTTng tracer :
> 
> - Rip apart ltt/ltt-core.c and put it in ltt/ltt-tracer.c. This
>  "builtin" part of LTTng can now sit in a module without any problem.
>  This can be done because we have the markers to abstract all
>  interactions with the tracer.
>  (will be done by myself soon)
> 
> - switch ltt-control.ko (currently over netlink) to debugfs
>  (being done by Fujistsu)
> 
> - Create a ltt-ascii.ko kernel module which merge-sorts the buffers and exports
>  them to userspace through a debugfs file.
>  (will be done by Fujistu)
> 
> - merge a simplified lttv in lttng
>  (will be done by myself)
> 
> As always, feel free to indicate if you are willing to help on any of
> these items. If you need some pointers to the current state of work for
> a particular item, just ask and I'll give you the pointer to the patch
> within the -lttng git tree.
> 
> Thanks,
> 
> Mathieu
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
>