Messages in this thread | | | From | Namhyung Kim <> | Date | Fri, 18 Apr 2014 15:55:33 +0900 | Subject | Re: [PATCH 0/3] perf top/tui: Fixes for percentage filter behavior |
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Hi Jiri,
On Fri, Apr 18, 2014 at 3:52 AM, Jiri Olsa <jolsa@redhat.com> wrote: > On Thu, Apr 17, 2014 at 10:38:19PM +0900, Namhyung Kim wrote: >> Hi Jiri, >> >> 2014-04-17 (목), 14:00 +0200, Jiri Olsa: >> > On Thu, Apr 17, 2014 at 04:53:23PM +0900, Namhyung Kim wrote: >> > > Hi, >> > > >> > > This is a small fixes for a bug in perf top I found during some tests. >> > > It gets segfault if symbol filter found no entries - accessing NULL >> > > pointer in that case. >> > >> > yep, I hit that yesterday as well, but I ended up just with >> > the patch below, your changes seems more comprehensive ;-) >> > going to review.. >> >> Well, the end result will be same, but I think it should have 0 >> nr_entries when there's no entry to show. > > also I hit another issue ;-) > > - running report on data with callchains, and the screen is populated to the middle > - press 'END' key and the cursor goes to the bottom of the screen (I can tell based > on the scrollbar), but there are no entries > > I could make the cursor appear by pressing UP arrow, I bisected to: > f214833 perf report: Add --percentage option > > not sure where's the problem
Hmm.. did you find it when running perf report? AFAIK there's a subtle problem of counting number of entries in perf report TUI with callchains. I wished fixing it but I was afraid of diving into the tui code. ;-p But I think it's a different one to the bug you reported.
Anyway I found that there's an inconsistency when handling hists->nr_entries. We're increasing hists->nr_entries when new sample comes in (ang not merged into an existing entry), but accesses the nr_entries before adding it to the hist browser (i.e. output tree). I suspect the original perf top code has similar problem already but it seems my change made it to be triggered easily.
Also when it moves hist entries to the output tree, it resets nr_entries and increases nr_entries again as they're moved. I think it's a problem on perf top since it'll loose the number of entries already existing on the output tree. I'm not sure how it has been working.. maybe I'm missing something.
I'm out of office now, I'll investigate it more when I'm back to office next week.
Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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