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Message-ID: <CACT4Y+Y_Mk9BHE0qVobsAp_ROSxQ+dVrbwHWkmg77B9YexQ4cw@mail.gmail.com>
Date: Mon, 13 Jan 2025 14:36:05 +0100
From: Dmitry Vyukov <dvyukov@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: irogers@...gle.com, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] perf hist: Deduplicate cmp/sort/collapse code
On Fri, 10 Jan 2025 at 14:01, Dmitry Vyukov <dvyukov@...gle.com> wrote:
>
> On Thu, 9 Jan 2025 at 22:43, Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > Hello,
> >
> > On Wed, Jan 08, 2025 at 08:36:53AM +0100, Dmitry Vyukov wrote:
> > > Application of cmp/sort/collapse fmt callbacks is duplicated 6 times.
> > > Factor it into a common helper function. NFC.
> >
> > It's interesting to use offsetof and cast it to functions. :)
>
> Is there a better way to do this?
> Intuitively I reached for member pointers, but then realized it's not
> a thing in C...
>
>
> > > Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
> > > Cc: Namhyung Kim <namhyung@...nel.org>
> > > Cc: Ian Rogers <irogers@...gle.com>
> > > Cc: linux-perf-users@...r.kernel.org
> > > Cc: linux-kernel@...r.kernel.org
> > > ---
> > > tools/perf/util/hist.c | 104 +++++++++++++++++------------------------
> > > tools/perf/util/hist.h | 2 -
> > > 2 files changed, 44 insertions(+), 62 deletions(-)
> > >
> > > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> > > index fff1345658016..8e4e844425370 100644
> > > --- a/tools/perf/util/hist.c
> > > +++ b/tools/perf/util/hist.c
> > > @@ -32,6 +32,9 @@
> > > #include <linux/time64.h>
> > > #include <linux/zalloc.h>
> > >
> > > +static int64_t hist_entry__cmp(struct hist_entry *left, struct hist_entry *right);
> > > +static int64_t hist_entry__collapse(struct hist_entry *left, struct hist_entry *right);
> > > +
> > > static bool hists__filter_entry_by_dso(struct hists *hists,
> > > struct hist_entry *he);
> > > static bool hists__filter_entry_by_thread(struct hists *hists,
> > > @@ -1292,19 +1295,27 @@ int hist_entry_iter__add(struct hist_entry_iter *iter, struct addr_location *al,
> > > return err;
> > > }
> > >
> > > -int64_t
> > > -hist_entry__cmp(struct hist_entry *left, struct hist_entry *right)
> > > +static int64_t
> > > +hist_entry__cmp_impl(struct perf_hpp_list *hpp_list, struct hist_entry *left,
> > > + struct hist_entry *right, unsigned long fn_offset,
> > > + bool ignore_dynamic, bool ignore_skipped)
> > > {
> > > + typedef int64_t (*fn_t)(struct perf_hpp_fmt *, struct hist_entry *, struct hist_entry *);
> >
> > Probably better to put it in util/hist.h and each members (cmp, collapse,
> > sort) use the typedef to make sure they remain in the same.
Good idea!. Done in v2
> Noted. But let's decide on the "perf hist: Fix bogus profiles when
> filters are enabled" first, that was the motivation for this
> refactoring.
>
>
> > > struct hists *hists = left->hists;
> > > struct perf_hpp_fmt *fmt;
> > > int64_t cmp = 0;
> > > + fn_t fn;
> > >
> > > - hists__for_each_sort_list(hists, fmt) {
> > > - if (perf_hpp__is_dynamic_entry(fmt) &&
> > > + perf_hpp_list__for_each_sort_list(hpp_list, fmt) {
> > > + if (ignore_dynamic && perf_hpp__is_dynamic_entry(fmt) &&
> > > !perf_hpp__defined_dynamic_entry(fmt, hists))
> > > continue;
> > >
> > > - cmp = fmt->cmp(fmt, left, right);
> > > + if (ignore_skipped && perf_hpp__should_skip(fmt, hists))
> > > + continue;
> > > +
> > > + fn = *(fn_t *)(((char *)fmt) + fn_offset);
> >
> > Doesn't just below work?
> >
> > fn = (void *)fmt + fn_offset;
No, this just calculates a pointer to the field that contains the
function pointer. But we also need to dereference that field and get
the function pointer.
> > Thanks,
> > Namhyung
> >
> >
> > > + cmp = fn(fmt, left, right);
> > > if (cmp)
> > > break;
> > > }
> > > @@ -1313,23 +1324,33 @@ hist_entry__cmp(struct hist_entry *left, struct hist_entry *right)
> > > }
> > >
> > > int64_t
> > > -hist_entry__collapse(struct hist_entry *left, struct hist_entry *right)
> > > +hist_entry__cmp(struct hist_entry *left, struct hist_entry *right)
> > > {
> > > - struct hists *hists = left->hists;
> > > - struct perf_hpp_fmt *fmt;
> > > - int64_t cmp = 0;
> > > + return hist_entry__cmp_impl(left->hists->hpp_list, left, right,
> > > + offsetof(struct perf_hpp_fmt, cmp), true, false);
> > > +}
> > >
> > > - hists__for_each_sort_list(hists, fmt) {
> > > - if (perf_hpp__is_dynamic_entry(fmt) &&
> > > - !perf_hpp__defined_dynamic_entry(fmt, hists))
> > > - continue;
> > > +static int64_t
> > > +hist_entry__sort(struct hist_entry *left, struct hist_entry *right)
> > > +{
> > > + return hist_entry__cmp_impl(left->hists->hpp_list, left, right,
> > > + offsetof(struct perf_hpp_fmt, sort), false, true);
> > > +}
> > >
> > > - cmp = fmt->collapse(fmt, left, right);
> > > - if (cmp)
> > > - break;
> > > - }
> > > +int64_t
> > > +hist_entry__collapse(struct hist_entry *left, struct hist_entry *right)
> > > +{
> > > + return hist_entry__cmp_impl(left->hists->hpp_list, left, right,
> > > + offsetof(struct perf_hpp_fmt, collapse), true, false);
> > > +}
> > >
> > > - return cmp;
> > > +static int64_t
> > > +hist_entry__collapse_hierarchy(struct perf_hpp_list *hpp_list,
> > > + struct hist_entry *left,
> > > + struct hist_entry *right)
> > > +{
> > > + return hist_entry__cmp_impl(hpp_list, left, right,
> > > + offsetof(struct perf_hpp_fmt, collapse), false, false);
> > > }
> > >
> > > void hist_entry__delete(struct hist_entry *he)
> > > @@ -1503,14 +1524,7 @@ static struct hist_entry *hierarchy_insert_entry(struct hists *hists,
> > > while (*p != NULL) {
> > > parent = *p;
> > > iter = rb_entry(parent, struct hist_entry, rb_node_in);
> > > -
> > > - cmp = 0;
> > > - perf_hpp_list__for_each_sort_list(hpp_list, fmt) {
> > > - cmp = fmt->collapse(fmt, iter, he);
> > > - if (cmp)
> > > - break;
> > > - }
> > > -
> > > + cmp = hist_entry__collapse_hierarchy(hpp_list, iter, he);
> > > if (!cmp) {
> > > he_stat__add_stat(&iter->stat, &he->stat);
> > > return iter;
> > > @@ -1730,24 +1744,6 @@ int hists__collapse_resort(struct hists *hists, struct ui_progress *prog)
> > > return 0;
> > > }
> > >
> > > -static int64_t hist_entry__sort(struct hist_entry *a, struct hist_entry *b)
> > > -{
> > > - struct hists *hists = a->hists;
> > > - struct perf_hpp_fmt *fmt;
> > > - int64_t cmp = 0;
> > > -
> > > - hists__for_each_sort_list(hists, fmt) {
> > > - if (perf_hpp__should_skip(fmt, a->hists))
> > > - continue;
> > > -
> > > - cmp = fmt->sort(fmt, a, b);
> > > - if (cmp)
> > > - break;
> > > - }
> > > -
> > > - return cmp;
> > > -}
> > > -
> > > static void hists__reset_filter_stats(struct hists *hists)
> > > {
> > > hists->nr_non_filtered_entries = 0;
> > > @@ -2449,21 +2445,15 @@ static struct hist_entry *add_dummy_hierarchy_entry(struct hists *hists,
> > > struct rb_node **p;
> > > struct rb_node *parent = NULL;
> > > struct hist_entry *he;
> > > - struct perf_hpp_fmt *fmt;
> > > bool leftmost = true;
> > >
> > > p = &root->rb_root.rb_node;
> > > while (*p != NULL) {
> > > - int64_t cmp = 0;
> > > + int64_t cmp;
> > >
> > > parent = *p;
> > > he = rb_entry(parent, struct hist_entry, rb_node_in);
> > > -
> > > - perf_hpp_list__for_each_sort_list(he->hpp_list, fmt) {
> > > - cmp = fmt->collapse(fmt, he, pair);
> > > - if (cmp)
> > > - break;
> > > - }
> > > + cmp = hist_entry__collapse_hierarchy(he->hpp_list, he, pair);
> > > if (!cmp)
> > > goto out;
> > >
> > > @@ -2521,16 +2511,10 @@ static struct hist_entry *hists__find_hierarchy_entry(struct rb_root_cached *roo
> > >
> > > while (n) {
> > > struct hist_entry *iter;
> > > - struct perf_hpp_fmt *fmt;
> > > - int64_t cmp = 0;
> > > + int64_t cmp;
> > >
> > > iter = rb_entry(n, struct hist_entry, rb_node_in);
> > > - perf_hpp_list__for_each_sort_list(he->hpp_list, fmt) {
> > > - cmp = fmt->collapse(fmt, iter, he);
> > > - if (cmp)
> > > - break;
> > > - }
> > > -
> > > + cmp = hist_entry__collapse_hierarchy(he->hpp_list, iter, he);
> > > if (cmp < 0)
> > > n = n->rb_left;
> > > else if (cmp > 0)
> > > diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
> > > index 1131056924d9c..6cff03eb043b7 100644
> > > --- a/tools/perf/util/hist.h
> > > +++ b/tools/perf/util/hist.h
> > > @@ -342,8 +342,6 @@ int hist_entry_iter__add(struct hist_entry_iter *iter, struct addr_location *al,
> > > struct perf_hpp;
> > > struct perf_hpp_fmt;
> > >
> > > -int64_t hist_entry__cmp(struct hist_entry *left, struct hist_entry *right);
> > > -int64_t hist_entry__collapse(struct hist_entry *left, struct hist_entry *right);
> > > int hist_entry__transaction_len(void);
> > > int hist_entry__sort_snprintf(struct hist_entry *he, char *bf, size_t size,
> > > struct hists *hists);
> > > --
> > > 2.47.1.613.gc27f4b7a9f-goog
> > >
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