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SubjectRe: Re: [RFC PATCH v1 0/2] perf: Support for SDT markers
(2014/02/26 17:18), Namhyung Kim wrote:
> Hi Masami and Hemant,
> On Tue, 25 Feb 2014 21:27:07 +0530, Hemant Kumar wrote:
>> On 02/25/2014 05:14 PM, Masami Hiramatsu wrote:
>>> (2014/02/24 18:14), Hemant Kumar wrote:
>>>> First, scan the binaries using :
>>>> # perf list sdt --scan
>>>> Creating a cache of SDT markers...
>>>> perf sdt cache created!
>>>> Use : "perf list sdt"
>>>> to see the SDT markers
>>> Hmm, in that case, I think you'd better introduce perf-sdt for scanning.
>>> e.g.
>>> # perf sdt --scan app
>> Hmm, this seems a better idea :)
>>> then you can add app to sdt cache, without app,
>>> # perf sdt --scan
>>> will just scans all binaries on the PATH and the libraries which listed
>>> by `ldconfig --print-caceh`
> What should be done with the new perf sdt command? If it's only
> intended to list the markers, I'd just suggest to add "perf list sdt" as
> this patch did.
> Plus I think it'd be better if event_glob pattern also looks for sdt
> markers so that user can find out a specific markers easily, e.g.:
> # perf list rtld:*
> or
> # perf list %rtld:*

Ah, that's a good idea :)

>>> And perf-list shows only the SDTs in the cache.
>> Well, what will be better? perf-list or perf-sdt or perf-list sdt??
>> If perf-list, then wouldn't it be a huge list!!
> The output of perf list is already a huge list and we paginate it. So I
> don't think it's gonna be a problem. :)


>>>> - Add support to probe these SDT markers and integrate with a previous patch
>>>> (support to perf to probe SDT markers) posted in lkml.
>>> Yeah, but I think we'd better choose another way to integrate it.
>>> Since SDT is like markers(static events), setting each of them via perf-probe is
>>> not intuitive. :) I'd like to use it as an event, e.g.
>>> # perf top -e "%libgcc:unwind"
>>> And perf top internally calls perf-probe to add new uprobe event, and
>>> clean the new event at exit.
>> Yeah! Right :) Makes sense.

Note that we will need an option to make it permanent (not clear the event on exit)
for people who want to use SDT event from ftrace. :)

>> Will implement the suggestions in the next version asap!
> That would be great!

Thank you!

IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory

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