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Re: Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
- From: Pekka Enberg <penberg at kernel dot org>
- To: Mark Wielaard <mjw at redhat dot com>
- Cc: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Hemant Kumar <hkshaw at linux dot vnet dot ibm dot com>, LKML <linux-kernel at vger dot kernel dot org>, Peter Zijlstra <peterz at infradead dot org>, Oleg Nesterov <oleg at redhat dot com>, hegdevasant at linux dot vnet dot ibm dot com, Ingo Molnar <mingo at redhat dot com>, Anton Arapov <anton at redhat dot com>, systemtap at sourceware dot org, Namhyung Kim <namhyung at kernel dot org>, aravinda at linux dot vnet dot ibm dot com
- Date: Tue, 29 Oct 2013 21:54:41 +0200
- Subject: Re: Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
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- References: <20131023044511 dot 1886 dot 82571 dot stgit at hemant-fedora> <20131023050502 dot 1886 dot 15779 dot stgit at hemant-fedora> <CAOJsxLFKm3TxeTmGjbpr1r4sZ8fHcM481-5BM_Cq0J8hhtvBqQ at mail dot gmail dot com> <526E4940 dot 8000608 at hitachi dot com> <526E5BA5 dot 7050103 at iki dot fi> <20131028141152 dot GA1040 at linux dot vnet dot ibm dot com> <526E72EC dot 9060400 at iki dot fi> <20131028173152 dot GB1040 at linux dot vnet dot ibm dot com> <526EA366 dot 4020204 at iki dot fi> <526F2949 dot 5000208 at hitachi dot com> <1383058315 dot 6521 dot 3158 dot camel at bordewijk dot wildebeest dot org>
On Tue, Oct 29, 2013 at 4:51 PM, Mark Wielaard <mjw@redhat.com> wrote:
> A nice user case to think about when designing this interface might be
> the java hotspot jvm (libjvm.so). It has SDT markers with the same name
> that might occur at multiple addresses depending on code path taken or
> compiler optimization. And there are multiple libjvm.so variants
> depending on whether the user uses the client or server VM. And users
> often have multiple major versions installed (both 1.6 and 1.7 are
> currently being shipped by some distros and can be installed in
> parallel).
>
> Normally a user that wants to monitor say the hotspot:gc__begin SDT
> probe wants to see that probe in whatever code path it happens and in
> whatever libjvm.so happens to be running (client or server and 1.6 or
> 1.7 version). But might still want to be able to specify a specific
> variant.
Agreed, it's an excellent use case.