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Re: [RFC] perf-cache command interface design
- From: Arnaldo Carvalho de Melo <acme at redhat dot com>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: Hemant Kumar <hemant at linux dot vnet dot ibm dot com>, Namhyung Kim <namhyung at kernel dot org>, linux-kernel at vger dot kernel dot org, srikar at linux dot vnet dot ibm dot com, peterz at infradead dot org, oleg at redhat dot com, hegdevasant at linux dot vnet dot ibm dot com, mingo at redhat dot com, systemtap at sourceware dot org, aravinda at linux dot vnet dot ibm dot com, penberg at iki dot fi, brendan dot d dot gregg at gmail dot com, "yrl dot pp-manager dot tt at hitachi dot com" <yrl dot pp-manager dot tt at hitachi dot com>
- Date: Tue, 11 Nov 2014 11:10:30 -0200
- Subject: Re: [RFC] perf-cache command interface design
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- References: <87lhnr5sbl dot fsf at sejong dot aot dot lge dot com> <54588905 dot 7040002 at linux dot vnet dot ibm dot com> <5458CD15 dot 4010101 at hitachi dot com> <874muew2hk dot fsf at sejong dot aot dot lge dot com> <5459E865 dot 6050207 at hitachi dot com> <545B1DDE dot 9000202 at linux dot vnet dot ibm dot com> <545C80F4 dot 4020905 at hitachi dot com> <54609A8C dot 4050308 at hitachi dot com> <20141110122321 dot GC4468 at redhat dot com> <5461B276 dot 50004 at hitachi dot com>
Em Tue, Nov 11, 2014 at 03:53:42PM +0900, Masami Hiramatsu escreveu:
> (2014/11/10 21:23), Arnaldo Carvalho de Melo wrote:
> > Em Mon, Nov 10, 2014 at 07:59:24PM +0900, Masami Hiramatsu escreveu:
> >> Here is the second try for the probe-cache. This version simplifies
> >> the synopsis, and unifies the SDT and probe caches.
> >> Please give me your comments/ideas!
> >>
> >> Command-line Synopsis
> >> =====================
> >> Add elf(or symbols) and probe-caches of SDT if exists in <FILES>
> >> perf cache --add <FILES> [--probe <SPEC>] # for user programs
> > Why the --probe above? Shouldn't this be just (if you are talking about
> > ELF files only):
> > perf cache --add <FILES>
> Yes, for the elf and sdt cache, we don't need --probe.
> Note that "[]" means optional. If we would like to add some probe cache,
> we need a spec of probe definition.
I understand that, its just that it looked superfluous at that specific
place, where you are explaining how to add ELF files.
> >> perf cache --kcore <FILE> [--probe <SPEC>] # for kcore ?
> > Adrian, aren't kcore files easily identifiable as such and thus could be
> > added as:
> > perf cache --add <FILES>
> >> perf cache --probe <SPEC> # for the current kernel
> > Why do we need a --probe here? Don't they always start with a character
> > that is seldomly used in ELF file names and thus we could get away with
> > not requiring --probe?
> This is only for adding the probe cache (not elf, nor sdt), which requires
> a probe definition. Moreover, I'd like to unify the specification of the
> probe definition with perf-probe. In that case, --probe is more natural.
What I meant was, what is wrong with replacing:
perf cache --probe <SPEC> # for the current kernel
With:
perf cache --add <PROBE-SPEC> # for the current kernel
And have it figure out that what is being added is a probe and do the
right thing?
> >> Remove caches related to <FILES> or <BUILDIDS>
> >> perf cache --remove <FILES>|<BUILDIDS>
> >>
> >> Show all probe caches(including SDT) or buildids
> >> perf cache --list [probe|buildid]
> >>
> >> Delete existing probe-cache entries for kernel, <PATH> or/and <BUILDID>.
> >> perf cacheã--probe-del [<GROUP>:]<EVENT>[@<PATH>][#<BUILDID>]
> >
> > Ditto, i.e. can't we just use:
> >
> > perf cacheã--remove [<GROUP>:]<EVENT>[@<PATH>][#<BUILDID>]
> >
> > And it figure out that this is a probe that is being removed?
>
> In most cases, it may be OK, but it is also possible to cause unexpected
> result when mis-typing. I think if <FILE> is always starting at '/', it
> is easy to identify.
We can keep the explicit switch (--probe-del) perhaps to resolve
ambiguities, if they happen, but make it so that it is not strictly
required for the common case.
- Thanks,
- Arnaldo