[ltt-dev] Make lttctl use new interface

[Mathieu Desnoyers]

* Zhaolei (zhaolei at cn.fujitsu.com) wrote:
> Mathieu Desnoyers ??:
> > * Zhaolei (zhaolei at cn.fujitsu.com) wrote:
> >> Hi, Mathieu
> >>
> >> I modified lttctl for support debugfs-based ltt-trace-control.
> >>
> >> This patch only modified interior method of control ltt trace,
> >> so command args are not changed.
> >>
> >> We can use this code without modify our user-manual, and lttv need not change
> >> too.
> >>
> >> But personaly, I'd like to design a set of new command arguments for lttctl in
> >> next step, for support each-channel buffer and overwrite control.
> >> And old cmd-args as -X, -V, -B, -z, -x, -v may be dropped(or change for easy
> >> to remember)
> >> For example:
> >> -c Create a trace
> >> -C Create a trace and start
> >> -d Destroy trace channels
> >> -D Stop and destroy trace channels
> >> ...
> >> or
> >> -c  Create a trace
> >> -cs Create a trace and start
> >> -d  Destroy trace channels
> >> -td Terminate and destroy trace channels
> >> ...
> >> But it we do, our unlucky users must read our new manual again : (
> >> What is your opinion?
> >>
> > 
> > Your patch looks great :) But I'd go directly for a command-line
> > breakage so we don't end up keeping legacy options. The sooner the
> > better.
> > 
> > I really like the -c, -C, -d, -D approach. Maybe we could have both of
> > your suggestions supported as aliases ?
> Hello, Mathieu

Hi Zhaolei,

> 
> I consider about following options:
> 
> Basic options:
> -c, --create tracename
> 	Create a trace
> -d, --destroy tracename
> 	Destroy trace channels
> -s, --start tracename
> 	Start tracing

--> terminate -> pause ?

-p, --pause tracename
	Pause tracing

Maybe we should add
  -r --read (comma separated channel list, e.g. -r "cpu,processes")
     Channels to read from
  -w, --write (disk, network, ...)
     Write trace data read from --read channel list through disk or
     network module.

> -h, --help
> 	Show help
> 
> Advanced options:
> --type
> 	Type of trace (ex. relay)
> --ltt_root
> 	LTT channels root path. (ex. /mnt/debugfs/ltt)

sounds good.

> -o, --option
> 	Set options, following operations are supported:
> 	cpu.bufnum=
> 	cpu.bufsize=
> 	cpu.overwrite=
> 	processes.bufnum=
> 	processes.bufsize=
> 	processes.overwrite=
> 	interrupts.bufnum=
> 	interrupts.bufsize=
> 	interrupts.overwrite=
> 	network.bufnum=
> 	network.bufsize=
> 	network.overwrite=
> 	modules.bufnum=
> 	modules.bufsize=
> 	modules.overwrite=
> 	metadata.bufnum=
> 	metadata.bufsize=
> 

Can we more generically say

  <channel>.bufnum=
  <channel>.bufsize=
  <channel>.overwrite=

? Because in a near future we won't be limited to the "fixed" channel
names, other tracers will be allowed to register their own channel.

> Integration options:
> -C, --create_start tracename
>         Create a trace and start
> -D, --stop_destroy tracename

stop -> Pause.
> 	Stop and destroy trace channels

Stop -> Pause. (that's equivalent)

> -A, --all_create tracename
> 	All mode: Create trace, spawn a lttd daemon, start tracing.
> 	(optionally, you can set LTT_DAEMON env. var.)

Yeah, that's not an easy one. I guess "super mega combo pack" would not
be much more descriptive neither. :)

So that would be the -cs -w disk ? (or -C -w disk). Maybe we could leave
that like this (two separate options), I think the -A would be too
confusing.


> -H, --hybrid_finish
> 	Stop tracing, dump flight recorder trace, destroy channels

That would become :

-D -r "list of channels" -w disk

Maybe we could also add a special -r keyword to specify "all overwrite"
or "all non-overwrite" channels. Notice that the standard "hybrid" mode
would be a :

lttctl -C -r "non-overwrite-wildcard" -w disk
...
lttctl -D -r "overwrite-wildcard" -w disk


> -p, --path path
> 	Path for write trace datas. (ex. /root/traces/example_trace)
> 	For -A and -H options

Nope, that would now go with -w option.

> -a, --append
> 	Append to trace
> 	For -A and -H options

This also would go with -w.

> -n, --dump_threads number
> 	Number of lttd threads
> 	For -A and -H options

Same here.

Mathieu

> 
> For example, create and start a trace, set cpu channel's subbuf number to 4,
> set network channel overwrite, and spawn a lttd daemon is:
> lttctl -A trace1 -p /tmp/trace1 -o cpu.bufsize=4 -o network.overwrite=1
> 
> Option of -A(--all_create) looks some strange(not very exact), I'd like to
> find a word means "Do all things for start a trace", do you have some suggestion?
> 
> And option of -H(--hybrid_finish) is not exact too, because I think we should
> make it include meaning of both "finish a trace" and "hybrid", but -H only have
> meaning of "hybrid".
> 
> What is your opinion about options above?
> (Because my English is pool, modify of option's comment is also welcome)
> 
> > 
> > If we change this, we should also update the lttv QUICKSTART file
> > accordingly.
> Yes, lttv also needs little update.
> 
> B.R.
> Zhaolei
> > 
> > Mathieu
> > 
> > 
> 

-- 
Mathieu Desnoyers
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