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Re: [RFC] Tracepoint proposal
- From: Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: KOSAKI Motohiro <kosaki dot motohiro at jp dot fujitsu dot com>, Takashi Nishiie <t-nishiie at np dot css dot fujitsu dot com>, 'Alexey Dobriyan' <adobriyan at gmail dot com>, 'Peter Zijlstra' <peterz at infradead dot org>, 'Steven Rostedt' <rostedt at goodmis dot org>, "'Frank Ch. Eigler'" <fche at redhat dot com>, 'Ingo Molnar' <mingo at elte dot hu>, 'LKML' <linux-kernel at vger dot kernel dot org>, 'systemtap-ml' <systemtap at sources dot redhat dot com>, 'Hideo AOKI' <haoki at redhat dot com>
- Date: Tue, 24 Jun 2008 13:46:13 -0400
- Subject: Re: [RFC] Tracepoint proposal
- References: <007601c8d5ca$18fa0e10$4aee2a30$@css.fujitsu.com> <48611B03.1000003@redhat.com> <20080625011951.D83E.KOSAKI.MOTOHIRO@jp.fujitsu.com> <48612879.5090809@redhat.com>
* Masami Hiramatsu (mhiramat@redhat.com) wrote:
> KOSAKI Motohiro wrote:
> >> Tracepoint
> >> - stored in a section
> >> - dynamic activation
> >> - no message
> >> - export kernel structure
> >> - arguments depending on points
> >> - high frequently called
> >> - no module support (kernel use only)
> >
> > Why Shouldn't kernel module use tracepoint?
> > technical problem? or any plicy exist?
>
> Good question, I think we don't want to export so much
> kernel internal structures. Since tracepoint tend to export
> raw kernel structure to user module, I thought it might be
> better not to export its interface to modules.
>
> However, I thought that again, and knew what Peter worried was
> about marker which exports marker list to user space.
> So, the issue is exporting internal structures to user space,
> not to modules. Thus, I think it can support modules also.
>
Agreed. It could be good to someday merge these tracepoint probes with
the mainline kernel so they can easily be adapted to tracepoint changes.
It seems correct to me for tracepoint probes to be either in the core
kernel or in modules, but I expect that they will be easier to maintain
within the tree.
Mathieu
> Thank you,
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America) Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com
>
--
Mathieu Desnoyers
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