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Re: [PATCH v3 5/5] perf/sdt: Add support to perf record to trace SDT events
- From: Namhyung Kim <namhyung at kernel dot org>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Hemant Kumar <hemant at linux dot vnet dot ibm dot com>, linux-kernel at vger dot kernel dot org, peterz at infradead dot org, oleg at redhat dot com, hegdevasant at linux dot vnet dot ibm dot com, mingo at redhat dot com, anton at redhat dot com, systemtap at sourceware dot org, aravinda at linux dot vnet dot ibm dot com, penberg at iki dot fi
- Date: Thu, 23 Oct 2014 17:21:21 +0900
- Subject: Re: [PATCH v3 5/5] perf/sdt: Add support to perf record to trace SDT events
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- References: <20141010104402 dot 15506 dot 73285 dot stgit at hemant-fedora> <20141010105914 dot 15506 dot 84827 dot stgit at hemant-fedora> <54475292 dot 20409 at hitachi dot com> <544768C6 dot 6090105 at linux dot vnet dot ibm dot com> <54477BE6 dot 2060006 at hitachi dot com> <20141023055422 dot GA27939 at linux dot vnet dot ibm dot com> <5448A141 dot 7050601 at hitachi dot com>
Hi Masami,
On Thu, 23 Oct 2014 15:33:37 +0900, Masami Hiramatsu wrote:
> (2014/10/23 14:54), Srikar Dronamraju wrote:
>> I am somehow not able to figure out how perf probe comes into the
>> current workflow.
>>
>> I think the current design was
>> 1. perf sdt-cache --add <file> (only once per file)
>> 2. perf record -e <sdt-event>
>>
>> So what is the additional thing that perf probe does or Is it going to
>> replace any of the above steps?
>
> 3. perf probe -a <sdt-event>
>
> And this will be done subsequently in this series (without user interface part).
> However, current implementation of 2. will do the following steps
>
> s1. get sdt event data from sdt-cache
> s2. set up sdt events with suppressing messages
> s3. do recording events
> (s4. and hiding existing sdt events from perf-probe --list)
> s5. remove sdt events
>
> So, what I proposed were ;
> - to implement s2., we can introduce --quiet(-q) option and use it
> instead of ->sdt flag checking
> - removing s4. and s5.
> - and add verification of existing sdt events at s2. if needed.
I'm okay with removing the s4 but not sure about the s5. In that case,
we might have many dynamic events in a system without noticing to users.
Thanks,
Namhyung
>
> This will simplify your patch and removing complex part of sdt-specific code.
> What would you think about this?
>
> Thank you,