Re: Re: [RFC PATCH 08/11] trace-cmd: Apply the trace-msg protocolfor communication between a server and clients

[Yoshihiro YUNOMAE]

(2013/08/28 23:42), Steven Rostedt wrote:
> On Wed, 28 Aug 2013 20:30:17 +0900
> Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@xxxxxxxxxxx> wrote:
>
> > (2013/08/27 22:05), Steven Rostedt wrote:
> > > On Tue, 27 Aug 2013 19:23:24 +0900
> > > Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@xxxxxxxxxxx> wrote:
> > >
> > > > OK, let me check that. Even if the old server will receive "V2", the
> > > > server will send port numbers instead of "V2" due to the old protocol.
> > > > In that time, the new client will disconnect from the old server and
> > > > the restarts with the old protocol. Is it OK?
> > >
> > > Yep, that's exactly what I meant ;-)
> >
> > I tried to implement the feature, but I found that sending just "V2"
> > from the new client is inappropriate. This is because the old server
> > doesn't respond to the client before receiving cpu numbers, page size,
> > and options. So, when the new client sends the first message, it should
> > send "V2\0<MAGIC_NUMBER>\00\0", I think. If so, the old server will
> > understand the message as cpus=0, pagesize=<MAGIC_NUMBER>, options=0,
> > and then it will send port numbers(actually \0). Note if <MAGIC_NUMBER>
> > is zero, the old server will die.
> >
> > Can I implement the first message of the new client as
> > "V2\0<MAGIC_NUMBER>\00\0"?
>
> If it works for both old and new server with old and new client (and
> all combinations) I'm fine with it.

OK, I'll submit trace-cmd patches as V2 in a few days.

Thanks,
Yoshihiro YUNOMAE

--
Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae.ez@xxxxxxxxxxx


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