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Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
- From: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- To: Pekka Enberg <penberg at iki dot fi>
- Cc: David Ahern <dsahern at gmail 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" <hegdevasant at linux dot vnet dot ibm dot com>, Ingo Molnar <mingo at redhat dot com>, "anton at redhat dot com" <anton at redhat dot com>, "systemtap at sourceware dot org" <systemtap at sourceware dot org>, Namhyung Kim <namhyung at kernel dot org>, "aravinda at linux dot vnet dot ibm dot com" <aravinda at linux dot vnet dot ibm dot com>, "yrl dot pp-manager dot tt at hitachi dot com" <yrl dot pp-manager dot tt at hitachi dot com>
- Date: Wed, 30 Oct 2013 19:22:38 +0900
- Subject: 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> <20131025125921 dot GA29424 at linux dot vnet dot ibm dot com> <F53BA283-A194-4057-8409-27FD3ECFDF2E at iki dot fi> <526A8C2B dot 7000401 at gmail dot com> <526E24EA dot 2040701 at iki dot fi> <526E9808 dot 4030607 at gmail dot com> <526EB0C3 dot 2080304 at iki dot fi>
(2013/10/29 3:45), Pekka Enberg wrote:
> On 10/28/13 6:59 PM, David Ahern wrote:
> > I often use perf-list to lookup an exact event name, and I do not want
> > to see it taking many seconds to minutes to run (not everyone is
> > running on an SSD). I also run perf on many different OS versions with
> > an NFS home directory, and do not want to see a cache explosion (I
> > have buildid disabled for this reason).
>
> I am talking about reasonable defaults - the 'default' part implies that
> people can change the behavior. So we absolutely should also have
> something like this for power users such as yourself:
>
> perf config sdt.scan false
Ah, I like this perf-config to store the default/customized values ;)
> That said, the 'reasonable' part suggests that 'perf list' must not take
> seconds or minutes (!) for every run. I'd start with implementing a
> naive scan and seeing where it takes us. It's not like it's rocket
> science to ignore network mounts or revert to a whitelist of paths if
> necessary.
I think it is reasonable to scan only $PATH and ld.so.cache (the result
of ldconfig --print-cache) by default. :)
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com