[ltt-dev] Updated TODO list before releasing LTTng buffering to LKML
Zhaolei
zhaolei at cn.fujitsu.com
Tue Oct 28 22:41:06 EDT 2008
> 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
>
>
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