From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Jiri Olsa <jolsa@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
kernel-team@lge.com, Masami Hiramatsu <mhiramat@kernel.org>,
Andi Kleen <andi@firstfloor.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Wang Nan <wangnan0@huawei.com>
Subject: Re: [PATCH/RFC 3/9] perf symbols: Discard symbols in kallsyms for loaded modules
Date: Sun, 25 Jun 2017 22:47:13 +0900 [thread overview]
Message-ID: <20170625134713.GA12099@danjae.aot.lge.com> (raw)
In-Reply-To: <20170623135105.GA4622@kernel.org>
On Fri, Jun 23, 2017 at 10:51:05AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Fri, Jun 23, 2017 at 02:48:21PM +0900, Namhyung Kim escreveu:
> > If a module is already loaded, it should have symbols and no need to
> > load new symbols from kallsyms. Actually kallsyms can have different
> > addresses if the module was reloaded.
>
> Well, if it is loaded, then it should match what is in kallsyms, no?
No, the perf.data was recorded with a module, and then the module was
modified and reloaded at the same address.
Maybe the word "loaded" can be confusing - if perf.data file has
symbols in the module v1 but kallsyms has symbols in the module v2.
So it needs to read symbols from the module v1 (in the build-id cache).
>
> > Current code just discards the first symbols only, but it should do the
> > same for all symbols in the module. Note that the kernel doesn't set
> > the dso->loaded bit so simply checking it would do the job IMHO.
>
> The kernel sets dso->loaded? Can you rephrase this part? And if this
> procedure doesn't set dso->loaded how can simply checking it do the job?
>
> Can you clarify the above sentence? Please elaborate the scenario more
> fully.
Oh, I made it confusing, sorry.. I mean that it's in the middle of
the dso__load() so the (kernel) dso->loaded bit was not set yet.
Thanks,
Namhyung
>
> - Arnaldo
>
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Cc: Wang Nan <wangnan0@huawei.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> > tools/perf/util/symbol.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> > index e7a98dbd2aed..74078ba595b3 100644
> > --- a/tools/perf/util/symbol.c
> > +++ b/tools/perf/util/symbol.c
> > @@ -787,11 +787,12 @@ static int dso__split_kallsyms(struct dso *dso, struct map *map, u64 delta)
> > curr_map = map;
> > goto discard_symbol;
> > }
> > -
> > - if (curr_map->dso->loaded &&
> > - !machine__is_default_guest(machine))
> > - goto discard_symbol;
> > }
> > +
> > + if (curr_map->dso->loaded &&
> > + !machine__is_default_guest(machine))
> > + goto discard_symbol;
> > +
> > /*
> > * So that we look just like we get from .ko files,
> > * i.e. not prelinked, relative to map->start.
> > --
> > 2.13.1
next prev parent reply other threads:[~2017-06-25 13:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-23 5:48 [PATCHSET/RFC 0/9] perf tools: Support out-of-tree modules Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 1/9] perf symbols: Use absolute address to fixup map address Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 2/9] perf tools: Remove duplicate code Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 3/9] perf symbols: Discard symbols in kallsyms for loaded modules Namhyung Kim
2017-06-23 13:51 ` Arnaldo Carvalho de Melo
2017-06-25 13:47 ` Namhyung Kim [this message]
2017-06-23 5:48 ` [PATCH/RFC 4/9] perf symbols: Load kernel module symbols ASAP Namhyung Kim
2017-06-23 14:26 ` Arnaldo Carvalho de Melo
2017-06-25 14:17 ` Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 5/9] perf symbols: Fixup the end address of kernel map properly Namhyung Kim
2017-06-23 14:27 ` Arnaldo Carvalho de Melo
2017-06-25 14:34 ` Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 6/9] perf symbols: Use already loaded module dso when loading kcore Namhyung Kim
2017-06-23 13:55 ` Arnaldo Carvalho de Melo
2017-06-25 13:54 ` Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 7/9] perf tools: Add symbol_conf.use_kcore Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 8/9] perf record: Not use kcore by default Namhyung Kim
2017-06-23 5:48 ` [PATCH/RFC 9/9] perf record: Add --module-dir option Namhyung Kim
2017-06-23 14:45 ` Arnaldo Carvalho de Melo
2017-06-25 14:43 ` Namhyung Kim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170625134713.GA12099@danjae.aot.lge.com \
--to=namhyung@kernel.org \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@kernel.org \
--cc=adrian.hunter@intel.com \
--cc=andi@firstfloor.org \
--cc=jolsa@kernel.org \
--cc=kernel-team@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=mingo@kernel.org \
--cc=wangnan0@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).