[ktap] Re: [PATCH 0/4] stapsdt initial support
- From: Azat Khuzhin <a3at.mail@xxxxxxxxx>
- To: Jovi Zhangwei <jovi.zhangwei@xxxxxxxxx>
- Date: Mon, 11 Nov 2013 11:08:42 +0400
On Mon, Nov 11, 2013 at 6:24 AM, Jovi Zhangwei <jovi.zhangwei@xxxxxxxxx> wrote:
> On Sun, Nov 10, 2013 at 3:50 AM, Azat Khuzhin <a3at.mail@xxxxxxxxx> wrote:
>> Jovi, If you prefer github, here is the link:
>> https://github.com/azat/ktap/compare/sdt-probes-v2
>>
> I didn't expect you implement it so fast, that's amazing :)
>
> Email would be more ease to review and post comments, the comments
> in github can be lost easily.
>
> Some comments from my side:
>
> 1) use "sdt" instead of "stapsdt"
> "sdt" would be much shorter, and it's so weird to use "stap"
> naming in ktap script. :)
It was already done before me.
And yeah I also though about it.
I will rename it shortly.
>
> 2) Segmentation fault for "trace sdt:/lib64/libc.so.6 {...}"
> No symbol given in that case.
Yeah, thanks!
This is a common case for parse_events_resolve_symbol(),
I will send another patch, because it also affects uprobes.
>
> 3) mulitple probe location with same sdt name
> For example(in my x86-64 machine):
> #readelf -n /lib64/libc.so.6 | grep lll_futex_wake
> Name: lll_futex_wake
> Name: lll_futex_wake
>
> So in this case, script like "trace
> sdt:/lib64/libc.so.6:lll_futex_wake" should match
> two probe location, so we have to write two uprobe events into debugfs.
>
> 4) support glob sdt name
> For example,"trace sdt:/lib64/libc.so.6:*" will match all sdt
> probes in /lib64/libc.so.6
>
> It seems that 3) and 4) need some big code change on eventdef.c,maybe we can
> abstract "add_uprobe" common function, it can be called when parse
> each valid sdt
> probe successfully. Please feel free to change that code to make it better.
I've already thought about this, but I hoped that this can be separate feature:
>> This implementation still needs in functions to obtain list of all available
>> markers, and also all available symbols (like perf) I think, to use patterns
>> for example, however this can wait a little.
And it's simpler to track smaller patch series.
>
> Thanks for your effort.
>
> Jovi
--
Respectfully
Azat Khuzhin
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