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Re: [RFC] perf-cache command interface design
- From: Namhyung Kim <namhyung at kernel dot org>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: Hemant Kumar <hemant at linux dot vnet dot ibm dot com>, Arnaldo Carvalho de Melo <acme at redhat dot com>, 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: Fri, 07 Nov 2014 23:43:27 +0900
- Subject: Re: [RFC] perf-cache command interface design
- Authentication-results: sourceware.org; auth=none
- References: <20141102105006 dot 21708 dot 28734 dot stgit at hemant-fedora> <20141102105557 dot 21708 dot 19032 dot stgit at hemant-fedora> <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>
Hi Masami,
2014-11-07 (ê), 17:21 +0900, Masami Hiramatsu:
> Hello,
>
> Here, I've tried to describe my idea of perf-cache subcommand interface.
> It is just a design review, not implemented yet :)
> Please give me your comments/ideas!
>
> Command-line Synopsis
> =====================
>
> Current "perf buildid-cache [options]" are directly mapped to
> "perf cache --buildid [options]".
>
> And adding --sdt for managing SDT caches as below.
>
> Add or update SDT events in <FILES>
> perf cache --sdt --add|--update <FILES>
>
> Remove all SDT events for <FILES>
> perf cache --sdt --remove <FILES>
>
> List all SDT events
> perf cache --sdt --list
>
> And --probes for managing probe-caches as below.
>
> Add new probe-cache entries for kernel, <PATH> or <MOD>.
> perf cache --probe [--exec <PATH>|--module <MOD>] --add <SPEC>
>
> Delete existing probe-cache entries for kernel, <PATH> or/and <BUILDID>.
> perf cache --probe --del [<GROUP>:]<EVENT>[@<PATH>][#<BUILDID>]
>
> Or remove all entires for given FILES
> perf cache --probe --remove <FILES>
>
> List the probe caches(including SDT) for kernel, <PATH>, or/and <BUILDID>.
> perf cache --probe --list [@<PATH>][#<BUILDID>]
>
> Query the probe definitions.
> perf cache --probe --query [<GROUP>:]<EVENT>[@<PATH>][#<BUILDID>]
>
> Note that --probes also can be used for managing SDT events, which has % prefix
> e.g.
> Add all SDT events for <PATH>
> perf cache --probe --exec <PATH> --add '%*:*'
>
> Remove some SDT events for <PATH>
> perf cache --probe --del '%some:events@<PATH>'
>
> Or remove all SDT events for <BUILDID>
> perf cache --probe --del '%*:*#<BUILDID>'
I'd prefer sub-command to option for this mandatory (and exclusive)
behavior. What about like this?
perf cache kprobe add [-m <module>] <spec> [<spec>...]
perf cache kprobe del [<group>:]<event> [<event>...]
perf cache kprobe list [-m <module>]
perf cache uprobe add -x <path> <spec> [<spec>...]
perf cache uprobe del [<group>:]<event> [<event>...]
perf cache uprobe list [-x <path>]
perf cache sdt [add|del|update] <file> [<file>...]
perf cache sdt list [-b <build-id>] [<file>...]
>
>
> File Format
> ===========
> All the cache files are placed under ~/.debug/ by default.
> The paths of buildid cache of binary/symbols are not changed.
>
> The SDT/probe caches are placed under the ~/.debug/.probes/path/to/bin/bu/ildid
> and that is linked to ~/.debug/.probes/.buildid/bu/ildid
> # To avoid conflict with files under /probes/*, I picked up .probes/.
However, to be used with perf record, we need a way to find a matching
probe cache file from a event name (or group/provider name, preferably).
What about having something like below:
$ cat ~/.debug/.probes/event.map
PROVIDER1 /path/to/some/where
PROVIDER2 /path/to/other/place
When perf record see a cached event used, it first searches its
provider/group name from the event.map file. And then read bulid-id
from the matching file on the path and finally find a cached event
definition from ~/.debug/.probes/.buildid/bu/ildid file.
>
> This SDT/probe caches contain probe-definitions as following format.
> ----
> #buildid:BUILDID
> #path:PATH
> p:%PROVIDER/EVENT PATH:OFFSET [ARGS]
It seems PATH is redundant and we don't need to repeat it everyline
IMHO. Since it need post-processing anyway, maybe it's better to just
make it simpler, like:
%:PROVIDER/EVENT OFFSET [ARGS]
Thanks,
Namhyung
> p:PROBE/EVENT _text+OFFSET [ARGS]
> ----
>
> Normal probes and SDT cache entries can be mixed in a cache file, we'll
> load all the entries and filter by % prefixes.
>
>
> Thank you,
>