Re: [PATCH v9 8/9] perf c2c: add function view browser UI and cacheline detail

[Ian Rogers]

On Mon, Aug 17, 2026 at 2:40 AM Jiebin Sun <jiebin.sun@xxxxxxxxx> wrote:
>
> Add the browser front end: create/run/delete the hist_browser and add the
> title. The d shortcut opens the existing per-cacheline detail view for the
> selected level-3 cacheline. Level-3 entries retain the source cacheline
> index, so the shortcut can locate the original entry without relying on a
> potentially ambiguous virtual address.
>
> Report a warning when the common model rejects a cacheline coalescing field
> list without `iaddr`. Without it, the detail histograms may already have
> merged samples from different functions and cannot support reliable
> function attribution.
>
> Keep visible-row accounting local to the function view by wrapping the
> generic browser refresh callback and recounting the currently reachable
> hierarchy before each redraw. This keeps navigation correct when a level-1
> row is collapsed while level-3 descendants remain expanded, without adding
> C2C-specific hooks to the shared hist_browser. Also handle Ctrl-C like the
> other function-view exit keys.
>
> Keep callchains hidden while the function browser runs, restoring the
> user's setting while opening the cacheline detail view.
>
> Wire the builder into perf_c2c__browse_function_view().
>
> Signed-off-by: Jiebin Sun <jiebin.sun@xxxxxxxxx>
> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
> Cc: Ian Rogers <irogers@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: James Clark <james.clark@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Thomas Falcon <thomas.falcon@xxxxxxxxx>
> Reviewed-by: Tianyou Li <tianyou.li@xxxxxxxxx>
> Reviewed-by: Wangyang Guo <wangyang.guo@xxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/builtin-c2c.c              |  10 ++
>  tools/perf/ui/browsers/Build          |   1 +
>  tools/perf/ui/browsers/c2c-function.c | 209 ++++++++++++++++++++++++++
>  tools/perf/util/c2c.h                 |  22 +++
>  4 files changed, 242 insertions(+)
>  create mode 100644 tools/perf/ui/browsers/c2c-function.c
>
> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index 16b00a36fdfc..715b75d42f2a 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c
> @@ -2745,11 +2745,18 @@ perf_c2c_browser__new(struct hists *hists)
>
>  static int perf_c2c__hists_browse(struct hists *hists)
>  {
> +       struct c2c_function_view_args func_args = {
> +               .cl_hists         = &c2c.hists,
> +               .cl_sort          = c2c.cl_sort,
> +               .symbol_full      = c2c.symbol_full,
> +               .browse_cacheline = perf_c2c__browse_cacheline,
> +       };
>         struct hist_browser *browser;
>         int key = -1;
>         static const char help[] =
>         " d             Display cacheline details \n"
>         " ENTER         Toggle callchains (if present) \n"
> +       " TAB           Switch to function view\n"
>         " q             Quit \n";
>
>         browser = perf_c2c_browser__new(hists);
> @@ -2771,6 +2778,9 @@ static int perf_c2c__hists_browse(struct hists *hists)
>                 case 'd':
>                         perf_c2c__browse_cacheline(browser->he_selection);
>                         break;
> +               case '\t':
> +                       perf_c2c__browse_function_view(&func_args);
> +                       break;
>                 case '?':
>                         ui_browser__help_window(&browser->b, help);
>                         break;
> diff --git a/tools/perf/ui/browsers/Build b/tools/perf/ui/browsers/Build
> index a07489e44765..ae67a2161f7d 100644
> --- a/tools/perf/ui/browsers/Build
> +++ b/tools/perf/ui/browsers/Build
> @@ -5,3 +5,4 @@ perf-ui-y += map.o
>  perf-ui-y += scripts.o
>  perf-ui-y += header.o
>  perf-ui-y += res_sample.o
> +perf-ui-y += c2c-function.o
> diff --git a/tools/perf/ui/browsers/c2c-function.c b/tools/perf/ui/browsers/c2c-function.c
> new file mode 100644
> index 000000000000..3d23e9d84981
> --- /dev/null
> +++ b/tools/perf/ui/browsers/c2c-function.c
> @@ -0,0 +1,209 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * C2C function browser - TUI front end for function-level sharing analysis
> + */
> +
> +#include <errno.h>
> +#include <inttypes.h>
> +#include <stdlib.h>
> +#include <sys/ttydefaults.h>
> +#include <linux/rbtree.h>
> +#include <linux/zalloc.h>
> +
> +#include "../browser.h"
> +#include "../keysyms.h"
> +#include "../libslang.h"
> +#include "../ui.h"
> +#include "../../util/c2c.h"
> +#include "../../util/debug.h"
> +#include "../../util/hist.h"
> +#include "../../util/symbol.h"
> +#include "hists.h"
> +
> +struct c2c_function_browser {
> +       struct hist_browser     hb;
> +       unsigned int            (*orig_refresh)(struct ui_browser *browser);
> +       int                     (*browse_cacheline)(struct hist_entry *he);
> +};
> +
> +/*
> + * Count visible entries in @root, descending only through visible, unfolded
> + * parents. Match hists__filter_entries(), which drives generic browser
> + * navigation, so the count cannot include rows the browser skips.
> + */
> +static u64
> +c2c_function__nr_visible_rows(struct rb_root_cached *root, float min_pcnt)
> +{
> +       struct rb_node *nd;
> +       u64 rows = 0;
> +
> +       for (nd = rb_first_cached(root); nd; nd = rb_next(nd)) {
> +               struct hist_entry *he = rb_entry(nd, struct hist_entry, rb_node);
> +
> +               /*
> +                * The generic refresh folds filtered parents and therefore hides
> +                * their subtree. A percentage-rejected parent is merely skipped;
> +                * if it is unfolded, qualifying descendants are still rendered.
> +                */
> +               if (he->filtered)
> +                       continue;
> +
> +               if (hist_entry__get_percent_limit(he) >= min_pcnt)
> +                       rows++;
> +               if (he->has_children && he->unfolded)
> +                       rows += c2c_function__nr_visible_rows(&he->hroot_out,
> +                                                            min_pcnt);
> +       }
> +       return rows;
> +}
> +
> +static void
> +c2c_function_browser__update_nr_entries(struct c2c_function_browser *browser)
> +{
> +       u64 nr_entries;
> +
> +       nr_entries = c2c_function__nr_visible_rows(&browser->hb.hists->entries,
> +                                                  browser->hb.min_pcnt);
> +       browser->hb.nr_non_filtered_entries = nr_entries;
> +       browser->hb.b.nr_entries = nr_entries;
> +}
> +
> +static unsigned int c2c_function_browser__refresh(struct ui_browser *ui_browser)
> +{
> +       struct hist_browser *hist_browser = container_of(ui_browser, struct hist_browser, b);
> +       struct c2c_function_browser *browser;
> +
> +       browser = container_of(hist_browser, struct c2c_function_browser, hb);
> +       c2c_function_browser__update_nr_entries(browser);
> +       return browser->orig_refresh(ui_browser);
> +}
> +
> +static int c2c_function_browser__title(struct hist_browser *browser,
> +                                      char *bf, size_t size)
> +{
> +       scnprintf(bf, size,
> +                 "Shared Data Functions Table     (%" PRIu64 " entries, sorted on Cycles %%)",
> +                 browser->hists->nr_non_filtered_entries);
> +       return 0;
> +}
> +
> +static struct c2c_function_browser *
> +c2c_function_browser__new(struct hists *hists,
> +                         int (*browse_cacheline)(struct hist_entry *he))
> +{
> +       struct c2c_function_browser *browser;
> +
> +       if (!hists)
> +               return NULL;
> +
> +       browser = zalloc(sizeof(*browser));
> +       if (!browser)
> +               return NULL;
> +
> +       hist_browser__init(&browser->hb, hists);
> +       browser->orig_refresh = browser->hb.b.refresh;
> +       browser->hb.b.refresh = c2c_function_browser__refresh;
> +       browser->browse_cacheline = browse_cacheline;
> +
> +       browser->hb.title = c2c_function_browser__title;
> +       browser->hb.c2c_filter = true;
> +       browser->hb.show_headers = true;
> +       /* Keep title line count consistent with forcing headers on. */
> +       browser->hb.b.extra_title_lines = hists->hpp_list->nr_header_lines;
> +       browser->hb.min_pcnt = 0.0;
> +
> +       return browser;
> +}
> +
> +static void c2c_function_browser__delete(struct c2c_function_browser *browser)
> +{
> +       free(browser);
> +}
> +
> +static int
> +c2c_browser__browse_cacheline(struct c2c_function_browser *browser,
> +                             struct hist_entry *he_selection)
> +{
> +       struct hist_entry *he = c2c_function__find_cacheline(he_selection);
> +
> +       return he ? browser->browse_cacheline(he) : -1;
> +}
> +
> +int perf_c2c__browse_function_view(struct c2c_function_view_args *args)
> +{
> +       struct c2c_function_browser *browser;
> +       struct hists *hists;
> +       bool saved_use_callchain = symbol_conf.use_callchain;
> +       int key, ret;
> +       static const char help[] =
> +       " d             Display details for the selected level-3 cacheline\n"
> +       " e/+           Expand/collapse the selected entry\n"
> +       " TAB/ESC/q/^C  Return to the cacheline view\n";
> +
> +       if (!args || !args->cl_hists || !args->browse_cacheline)
> +               return -EINVAL;
> +
> +       /*
> +        * Function view does not display callchains; cacheline detail temporarily
> +        * restores them.
> +        */
> +       symbol_conf.use_callchain = false;
> +
> +       ret = c2c_function__build(args->cl_hists, args->cl_sort,
> +                                 args->symbol_full, &hists);
> +       if (ret) {
> +               if (ret == -EOPNOTSUPP)
> +                       ui__warning("The function view requires iaddr in --coalesce.\n");
> +               else
> +                       ui__error("Failed to build function view hierarchy (ret=%d)\n", ret);
> +               goto out;
> +       }
> +
> +       browser = c2c_function_browser__new(hists, args->browse_cacheline);
> +       if (!browser) {
> +               ret = -ENOMEM;
> +               goto out_reset;
> +       }
> +
> +       /* Reset abort key so we can receive Ctrl-C as a key. */
> +       SLang_reset_tty();
> +       SLang_init_tty(0, 0, 0);
> +       SLtty_set_suspend_state(true);
> +
> +       while (1) {
> +               c2c_function_browser__update_nr_entries(browser);
> +               key = hist_browser__run(&browser->hb, "? - help", true, 0);
> +
> +               switch (key) {
> +               case 'q':
> +               case K_TAB:
> +               case K_ESC:
> +               case CTRL('c'):
> +                       goto browser_done;
> +               case 'd':
> +                       /* Cacheline detail honors the user's callchain setting. */
> +                       symbol_conf.use_callchain = saved_use_callchain;
> +                       c2c_browser__browse_cacheline(browser, browser->hb.he_selection);
> +                       /*
> +                        * Preserve any toggle made in the detail view, then
> +                        * re-disable callchain for the function view.
> +                        */
> +                       saved_use_callchain = symbol_conf.use_callchain;
> +                       symbol_conf.use_callchain = false;
> +                       break;
> +               case '?':
> +                       ui_browser__help_window(&browser->hb.b, help);
> +                       break;
> +               default:
> +                       break;
> +               }
> +       }
> +
> +browser_done:
> +       c2c_function_browser__delete(browser);
> +out_reset:
> +       c2c_function__reset();
> +out:
> +       symbol_conf.use_callchain = saved_use_callchain;
> +       return ret;
> +}
> diff --git a/tools/perf/util/c2c.h b/tools/perf/util/c2c.h
> index 6548b9ba81f1..53f024e25d99 100644
> --- a/tools/perf/util/c2c.h
> +++ b/tools/perf/util/c2c.h
> @@ -110,4 +110,26 @@ void c2c_function__reset(void);
>  /* Valid only between a successful build and c2c_function__reset(). */
>  struct hist_entry *c2c_function__find_cacheline(struct hist_entry *he);
>
> +/* Inputs and TUI callback supplied by the c2c command. */
> +struct c2c_function_view_args {
> +       /* Source cacheline histograms used by the common model. */
> +       struct c2c_hists        *cl_hists;
> +       /* --coalesce field list, used to require iaddr. */
> +       const char              *cl_sort;
> +       /* Do not cap long symbol names. */
> +       bool                     symbol_full;
> +       /* Open the cacheline detail view for @he. */
> +       int                     (*browse_cacheline)(struct hist_entry *he);
> +};
> +
> +#ifdef HAVE_SLANG_SUPPORT
> +int perf_c2c__browse_function_view(struct c2c_function_view_args *args);
> +#else
> +static inline int
> +perf_c2c__browse_function_view(struct c2c_function_view_args *args __maybe_unused)
> +{
> +       return 0;
> +}
> +#endif
> +
>  #endif /* __PERF_UTIL_C2C_H */
> --
> 2.52.0
>