[PATCH v2 2/2] perf top: support hotkey to change sort order

From: Jin Yao
Date: Wed Mar 25 2020 - 01:35:03 EST


It would be nice if we can use a hotkey in perf top browser to
select a event for sorting.

For example,
perf top --group -e cycles,instructions,cache-misses

Samples
Overhead Shared Object Symbol
40.03% 45.71% 0.03% div [.] main
20.46% 14.67% 0.21% libc-2.27.so [.] __random_r
20.01% 19.54% 0.02% libc-2.27.so [.] __random
9.68% 10.68% 0.00% div [.] compute_flag
4.32% 4.70% 0.00% libc-2.27.so [.] rand
3.84% 3.43% 0.00% div [.] rand@plt
0.05% 0.05% 2.33% libc-2.27.so [.] __strcmp_sse2_unaligned
0.04% 0.08% 2.43% perf [.] perf_hpp__is_dynamic_en
0.04% 0.02% 6.64% perf [.] rb_next
0.04% 0.01% 3.87% perf [.] dso__find_symbol
0.04% 0.04% 1.77% perf [.] sort__dso_cmp

When user press hotkey '2' (event index, starting from 0), it indicates
to sort output by the third event in group (cache-misses).

Samples
Overhead Shared Object Symbol
4.07% 1.28% 6.68% perf [.] rb_next
3.57% 3.98% 4.11% perf [.] __hists__insert_output
3.67% 11.24% 3.60% perf [.] perf_hpp__is_dynamic_e
3.67% 3.20% 3.20% perf [.] hpp__sort_overhead
0.81% 0.06% 3.01% perf [.] dso__find_symbol
1.62% 5.47% 2.51% perf [.] hists__match
2.70% 1.86% 2.47% libc-2.27.so [.] _int_malloc
0.19% 0.00% 2.29% [kernel] [k] copy_page
0.41% 0.32% 1.98% perf [.] hists__decay_entries
1.84% 3.67% 1.68% perf [.] sort__dso_cmp
0.16% 0.00% 1.63% [kernel] [k] clear_page_erms

Now the output is sorted by cache-misses.

v2:
---
Zero the history if hotkey is pressed.

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
tools/perf/builtin-top.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 494c7b9a1022..29ddae7e1805 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -616,6 +616,7 @@ static void *display_thread_tui(void *arg)
.arg = top,
.refresh = top->delay_secs,
};
+ int ret;

/* In order to read symbols from other namespaces perf to needs to call
* setns(2). This isn't permitted if the struct_fs has multiple users.
@@ -626,6 +627,7 @@ static void *display_thread_tui(void *arg)

prctl(PR_SET_NAME, "perf-top-UI", 0, 0, 0);

+repeat:
perf_top__sort_new_samples(top);

/*
@@ -638,13 +640,18 @@ static void *display_thread_tui(void *arg)
hists->uid_filter_str = top->record_opts.target.uid_str;
}

- perf_evlist__tui_browse_hists(top->evlist, help, &hbt,
+ ret = perf_evlist__tui_browse_hists(top->evlist, help, &hbt,
top->min_percent,
&top->session->header.env,
!top->record_opts.overwrite,
&top->annotation_opts);

- stop_top();
+ if (ret == K_RELOAD) {
+ top->zero = true;
+ goto repeat;
+ } else
+ stop_top();
+
return NULL;
}

--
2.17.1