From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Andres Freund <andres@anarazel.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: "perf hists browser: Support flat callchains" appears to have broken parent reporting
Date: Wed, 30 Mar 2016 18:07:39 -0300 [thread overview]
Message-ID: <20160330210738.GF3420@kernel.org> (raw)
In-Reply-To: <20160330160010.GA1557@danjae>
Em Thu, Mar 31, 2016 at 01:00:10AM +0900, Namhyung Kim escreveu:
> Hi Andres,
>
> On Wed, Mar 30, 2016 at 04:19:26PM +0200, Andres Freund wrote:
> > On 2016-03-30 10:46:34 -0300, Arnaldo Carvalho de Melo wrote:
> > > Em Wed, Mar 30, 2016 at 02:34:18PM +0200, Andres Freund escreveu:
> > > > Hi,
> > > >
> > > > 4b3a3212233a - "perf hists browser: Support flat callchains" seems to
> > > > have broken callchain display in tui mode when using !flat mode, or at
> > > > least changed it in an unintended manner.
> > >
> > > humm, at first I thought this would be related to --percent-limit...
> >
> > I'm not using --percent-limit. Just to be sure, I did explicitly set it
> > to various values, and it looks unrelated.
> >
> > > What tree/branch are you using? Can you try pressing 'L' to play with
> > > the percent limit?
> >
> > I'm primarily using linus' tree, and bisected the behavioural down to
> > that individual commit.
>
> Thanks for reporting and finding this!
Yeah, I noticed it now, we really need to do the equivalent of:
perf report --tui
E
P
Then get the perf.hist.N file before a patch and after it, to see if the
output changed :-\
Ditto for 'perf report --stdio' > before, after, diff.
- Arnaldo
> > It's somewhat weird that --stdio doesn't show the problem, but --tui
> > does. Hm.
> >
> >
> > I don't know the perf code at all, but skimming through the commit, the
> > following hunk looks suspicious:
> >
> > @@ -263,7 +295,7 @@ static void callchain_node__init_have_children(struct callchain_node *node,
> > chain = list_entry(node->val.next, struct callchain_list, list);
> > chain->has_children = has_sibling;
> >
> > - if (!list_empty(&node->val)) {
> > + if (node->val.next != node->val.prev) {
> > chain = list_entry(node->val.prev, struct callchain_list, list);
> > chain->has_children = !RB_EMPTY_ROOT(&node->rb_root);
> > }
> >
> > Reverting that individual change fixes things. I'm not actually sure
> > what the post 4b3a3212233a version actually tests for?
>
> Yeah, this is it. It's my fault that I thought if the first chain
> (node->val.next) was set by has_sibling, no need to go to the body
> of the "if" statement when next == prev case. But it's not...
>
> >
> >
> > I think that actually explains why stdio works - nodes are always
> > unfolded in it, thus ->has_children isn't looked at.
>
> Right, the ->has_children thing is only for TUI code which
> folds/collapses the entries dynamically.
>
> Do you mind resending the fix as a formal patch with my ack ?
>
> Thanks,
> Namhyung
prev parent reply other threads:[~2016-03-30 21:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 12:34 "perf hists browser: Support flat callchains" appears to have broken parent reporting Andres Freund
2016-03-30 13:46 ` Arnaldo Carvalho de Melo
2016-03-30 14:19 ` Andres Freund
2016-03-30 16:00 ` Namhyung Kim
2016-03-30 19:02 ` Andres Freund
2016-03-31 6:33 ` [tip:perf/urgent] perf hists: Fix determination of a callchain node's childlessness tip-bot for Andres Freund
2016-04-16 19:46 ` Andres Freund
2016-04-18 14:07 ` Arnaldo Carvalho de Melo
2016-04-18 14:25 ` Andres Freund
2016-05-02 22:17 ` Greg KH
2016-05-02 22:25 ` Andres Freund
2016-05-02 23:24 ` Greg KH
2016-05-02 23:34 ` Andres Freund
2016-03-30 21:07 ` Arnaldo Carvalho de Melo [this message]
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=20160330210738.GF3420@kernel.org \
--to=acme@kernel.org \
--cc=a.p.zijlstra@chello.nl \
--cc=andres@anarazel.de \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
/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).