Hello, This patchset tries to fix bugs in percentage handling which is recently changed. The perf top with symbol filter could cause a segfault (NULL pointer dereference) if the filter found no entry. In this patchset, I moved accounting of various histogram stats to be calculated at the time it actually shown to users. Although I tested it on my system for a while, it needs more testing since it'll affect behaviors of many commands/usages. There're three main fields in the hists->stats to affect the output: number of samples, number of hist entries and total periods. Also there're three stages to process samples: at first, samples are converted to a hist entry and added to the input tree, and then they are moved to the collapsed tree if needed, and finally they're moved to the output tree to be shown to user. The (part of) stats are accounted when samples are added to the input tree and then reset before moving to the output tree, and re-counted during insertion to the output tree. I can see some reason to do it this way but it's basically not necessary and could make a problem in multi-threaded programs like perf top. The perf report does all these passes sequentially in a single thread so it seems no problem. But perf top uses two threads - one for gathering samples (in the input tree) and another for (collapsing and) moving them to the output tree. Thus accounting stat in parallel can result in an inaccurate stats and the output. So I'd like to get rid of the accounting on the input stage as you can see it just gets dropped before doing output resort. I originally make the all three stats are accounted when doing output resort but changed mind to account number of samples in the input stage and others in the output stage. Because it'd make more sense accounting number of events (sample event) in the input stage (as all other events are also accounted in the input stage) and it'd make less changes in code. So yes, it has a same problem of inaccurate number of samples, but its impact should be smaller than other stats - seeing increasing sample count (could be slightly inaccurate) without new entries in the browser. You can get this on the 'perf/percentage-v11' branch (yes, v11 - as it's continued from my previous series) in my tree git://git.kenrel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Any comments, review and testing are welcomed. Thanks, Namhyung Namhyung Kim (7): perf report: Count number of entries separately perf tools: Account entry stats when it's added to the output tree perf hists: Add missing update on filtered stats in hists__decay_entries() perf ui/tui: Fix off-by-one in hist_browser__update_nr_entries() perf ui/tui: Rename hist_browser__update_nr_entries() perf top/tui: Update nr_entries properly after a filter is applied perf hists/tui: Count callchain rows separately tools/perf/builtin-annotate.c | 3 +- tools/perf/builtin-diff.c | 23 ++++++----- tools/perf/builtin-report.c | 58 ++++++++++++--------------- tools/perf/ui/browsers/hists.c | 86 ++++++++++++++++++++++++++-------------- tools/perf/util/hist.c | 89 +++++++++++++++++++++++++++--------------- tools/perf/util/hist.h | 9 ++++- 6 files changed, 162 insertions(+), 106 deletions(-) -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/