[ltt-dev] Make lttctl use new interface

[Mathieu Desnoyers]

* Zhaolei (zhaolei at cn.fujitsu.com) wrote:
> * From: "Mathieu Desnoyers" <mathieu.desnoyers at polymtl.ca>
> >* 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
> > 
> Hello, Mathieu
> 
> Thanks for your suggestion.
> 
> I think -r must specify non-overwrite channels with -C, and must specify
> overwrite channels with -D.
> 
> Instead of select some channel to dump, why not just trace some of channel,
> then we can dump all non-overwrite channels with -C and dump all overwrite
> channels with -D.
> 
> For example:
> Trace network and process channel with non-overwrite mode, and trace cpu channel
> with overwrite mode, other channel are not traced when we start a new trace.
> Then we can dump all non-overwrite channels(network and process channel)
> in tracing, and dump all overwrite channels(cpu channel) when we finished trace.
> 
> It can reduce system load when we only want to trace some channels.
> 
> B.R.
> Zhaolei
> 


Yep, it looks good and easy to understand.

Mathieu

> > 
> >> -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
> > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> > 
> >
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-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68