Messages in this thread Patch in this message | | | Subject | Re: [PATCH] perf annotate: Fix sample events lost in stdio mode | From | Yang Jihong <> | Date | Fri, 12 Mar 2021 11:24:00 +0800 |
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Hello, Namhyung
On 2021/3/11 22:42, Namhyung Kim wrote: > Hi, > > On Thu, Mar 11, 2021 at 5:48 PM Yang Jihong <yangjihong1@huawei.com> wrote: >> >> Hello, >> >> On 2021/3/6 16:28, Yang Jihong wrote: >>> In hist__find_annotations function, since have a hist_entry per IP for the same >>> symbol, we free notes->src to signal already processed this symbol in stdio mode; >>> when annotate, entry will skipped if notes->src is NULL to avoid repeated output. > > I'm not sure it's still true that we have a hist_entry per IP. > Afaik the default sort key is comm,dso,sym which means it should have a single > hist_entry for each symbol. It seems like an old comment.. > Emm, yes, we have a hist_entry for per IP. a member named "sym" in struct "hist_entry" points to symbol, different IP may point to the same symbol.
The hist_entry struct is as follows: struct hist_entry { ... struct map_symbol ms; ... }; struct map_symbol { struct maps *maps; struct map *map; struct symbol *sym; };
>>> >>> However, there is a problem, for example, run the following command: >>> >>> # perf record -e branch-misses -e branch-instructions -a sleep 1 >>> >>> perf.data file contains different types of sample event. >>> >>> If the same IP sample event exists in branch-misses and branch-instructions, >>> this event uses the same symbol. When annotate branch-misses events, notes->src >>> corresponding to this event is set to null, as a result, when annotate >>> branch-instructions events, this event is skipped and no annotate is output. >>> >>> Solution of this patch is to add a u8 member to struct sym_hist and use a bit to >>> indicate whether the symbol has been processed. >>> Because different types of event correspond to different sym_hist, no conflict >>> occurs. >>> --- >>> tools/perf/builtin-annotate.c | 22 ++++++++++++++-------- >>> tools/perf/util/annotate.h | 4 ++++ >>> 2 files changed, 18 insertions(+), 8 deletions(-) >>> >>> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c >>> index a23ba6bb99b6..c8c67892ae82 100644 >>> --- a/tools/perf/builtin-annotate.c >>> +++ b/tools/perf/builtin-annotate.c >>> @@ -372,15 +372,21 @@ static void hists__find_annotations(struct hists *hists, >>> if (next != NULL) >>> nd = next; >>> } else { >>> - hist_entry__tty_annotate(he, evsel, ann); >>> + struct sym_hist *h = annotated_source__histogram(notes->src, >>> + evsel->idx); >>> + >>> + if (h->processed == 0) { >>> + hist_entry__tty_annotate(he, evsel, ann); >>> + >>> + /* >>> + * Since we have a hist_entry per IP for the same >>> + * symbol, set processed flag of evsel in sym_hist >>> + * to signal we already processed this symbol. >>> + */ >>> + h->processed = 1; >>> + } >>> + >>> nd = rb_next(nd); >>> - /* >>> - * Since we have a hist_entry per IP for the same >>> - * symbol, free he->ms.sym->src to signal we already >>> - * processed this symbol. >>> - */ >>> - zfree(¬es->src->cycles_hist); >>> - zfree(¬es->src); >>> } >>> } >>> } >>> diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h >>> index 096cdaf21b01..89872bfdc958 100644 >>> --- a/tools/perf/util/annotate.h >>> +++ b/tools/perf/util/annotate.h >>> @@ -228,6 +228,10 @@ void symbol__calc_percent(struct symbol *sym, struct evsel *evsel); >>> struct sym_hist { >>> u64 nr_samples; >>> u64 period; >>> + >>> + u8 processed : 1, /* whether symbol has been processed, used for annotate */ >>> + __reserved : 7; > > I think just a bool member is fine. > OK, I have submitted the v2 patch and changed to bool member, new patch is as follows, look forward to your review: https://lore.kernel.org/patchwork/patch/1393901/
>>> + >>> struct sym_hist_entry addr[]; >>> }; >>> >>> >> Please check whether this solution is feasible, look forward to your review. > > What about this? (not tested) > > diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c > index a23ba6bb99b6..a91fe45bd69f 100644 > --- a/tools/perf/builtin-annotate.c > +++ b/tools/perf/builtin-annotate.c > @@ -374,13 +374,6 @@ static void hists__find_annotations(struct hists *hists, > } else { > hist_entry__tty_annotate(he, evsel, ann); > nd = rb_next(nd); > - /* > - * Since we have a hist_entry per IP for the same > - * symbol, free he->ms.sym->src to signal we already > - * processed this symbol. > - */ > - zfree(¬es->src->cycles_hist); > - zfree(¬es->src); > } > } > } > This solution may have the following problem: For example, if two sample events are in two different processes but in the same symbol, repeated output may occur. Therefore, a flag is required to indicate whether the symbol has been processed to avoid repeated output. > Thanks, > Namhyung > . > Thanks, Yang .
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