Re: Scrolling down broken with "perf top --hierarchy"

From: Markus Trippelsdorf
Date: Mon Oct 10 2016 - 13:54:55 EST


On 2016.10.08 at 13:21 +0200, Markus Trippelsdorf wrote:
> On 2016.10.07 at 07:09 +0200, Markus Trippelsdorf wrote:
> > On 2016.10.07 at 06:56 +0200, Markus Trippelsdorf wrote:
> > > On 2016.10.07 at 06:32 +0200, Markus Trippelsdorf wrote:
> > > > On 2016.10.07 at 13:22 +0900, Namhyung Kim wrote:
> > > > > On Fri, Oct 07, 2016 at 05:51:18AM +0200, Markus Trippelsdorf wrote:
> > > > > > On 2016.10.07 at 10:17 +0900, Namhyung Kim wrote:
> > > > > > > On Thu, Oct 06, 2016 at 06:33:33PM +0200, Markus Trippelsdorf wrote:
> > > > > > > > Scrolling down is broken when using "perf top --hierarchy".
> > > > > > > > When it starts up everything is OK and one can scroll up and down to all
> > > > > > > > entries. But as further and further new entries get added to the list,
> > > > > > > > scrolling down is blocked (at the position of the last entry that was
> > > > > > > > shown directly after startup).
> > > > > > >
> > > > > > > I think below patch will fix the problem. Please check.
> > > > > >
> > > > > > Yes. It works fine now. Many thanks.
> > > > >
> > > > > Good. Can I add your Tested-by then?
> > > >
> > > > Sure.
> > >
> > > And BTW symbols are currently always cut off at 60 characters in
> > > expanded entries.
> >
> > Hmm, no. Sometimes they are cut off, sometimes they are not. I haven't
> > figured out what triggered this strange behavior.
>
> Here is an example:
>
> % echo $COLUMNS
> 179
> % perf top --hierarchy
> + 34.81% [kernel]
> - 20.89% chrome
> 0.51% [.] v8::internal::IncrementalMarking:
> 0.43% [.] tc_malloc
> 0.29% [.] sqlite3BtreeMovetoUnpacked
> 0.28% [.] tc_free
> 0.24% [.] v8::internal::BodyDescriptorBase:
> 0.24% [.] sqlite3VdbeExec
> 0.22% [.] v8::internal::MarkCompactCollecto
> 0.19% [.] blink::SelectorChecker::checkOne
> 0.19% [.] SkBlitRow::Color32
> 0.18% [.] SkBlitLCD16OpaqueRow_SSE2
> 0.17% [.] btreeInitPage.part.366
> 0.16% [.] blink::SelectorChecker::matchSele
> 0.15% [.] blink::ElementRuleCollector::coll
> 0.15% [.] blink::CSSTokenizer::consumeName
> 0.14% [.] sqlite3GetVarint
> 0.13% [.] operator new[]
> 0.12% [.] FPDFAPI_inflate_fast
> 0.11% [.] v8::internal::HeapObject::SizeFro
> 0.09% [.] tracked_objects::ThreadData::Tall
> ...

To continue this monologue, perf doesn't even look at these entries. So some
hists__calc_col_len() calls seem to be missing for the "perf top --hierarchy"
case or hists__reset_col_len() is called too early or too often.

Anyway, the following hack "fixes" the issue for me:

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index b02992efb513..7e468fa56980 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -67,7 +67,7 @@ void hists__calc_col_len(struct hists *hists, struct hist_entry *h)
* +3 accounts for ' y ' symtab origin info
*/
if (h->ms.sym) {
- symlen = h->ms.sym->namelen + 4;
+ symlen = 200;
if (verbose)
symlen += BITS_PER_LONG / 4 + 2 + 3;
hists__new_col_len(hists, HISTC_SYMBOL, symlen);


--
Markus