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Message-ID: <Z1dyNuTsCgsY3TAZ@google.com>
Date: Mon, 9 Dec 2024 14:41:58 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Chun-Tse Shao <ctshao@...gle.com>
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...hat.com,
acme@...nel.org, mark.rutland@....com,
alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
irogers@...gle.com, adrian.hunter@...el.com,
kan.liang@...ux.intel.com, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v4 1/3] perf lock: Fix parse_lock_type which only
retrieve one lock flag
On Mon, Dec 09, 2024 at 12:01:00PM -0800, Chun-Tse Shao wrote:
> `parse_lock_type` can only add the first lock flag in `lock_type_table`
> given input `str`. For example, for `Y rwlock`, it only adds `rwlock:R`
> into this perf session. Another example is for `-Y mutex`, it only adds
> the mutex without `LCB_F_SPIN` flag. The patch fixes this issue, makes
> sure both `rwlock:R` and `rwlock:W` will be added with `-Y rwlock`, and
> so on.
>
> Testing:
> $ ./perf lock con -ab -Y mutex,rwlock -- perf bench sched pipe
> # Running 'sched/pipe' benchmark:
> # Executed 1000000 pipe operations between two processes
>
> Total time: 9.313 [sec]
>
> 9.313976 usecs/op
> 107365 ops/sec
> contended total wait max wait avg wait type caller
>
> 176 1.65 ms 19.43 us 9.38 us mutex pipe_read+0x57
> 34 180.14 us 10.93 us 5.30 us mutex pipe_write+0x50
> 7 77.48 us 16.09 us 11.07 us mutex do_epoll_wait+0x24d
> 7 74.70 us 13.50 us 10.67 us mutex do_epoll_wait+0x24d
> 3 35.97 us 14.44 us 11.99 us rwlock:W ep_done_scan+0x2d
> 3 35.00 us 12.23 us 11.66 us rwlock:W do_epoll_wait+0x255
> 2 15.88 us 11.96 us 7.94 us rwlock:W do_epoll_wait+0x47c
> 1 15.23 us 15.23 us 15.23 us rwlock:W do_epoll_wait+0x4d0
> 1 14.26 us 14.26 us 14.26 us rwlock:W ep_done_scan+0x2d
> 2 14.00 us 7.99 us 7.00 us mutex pipe_read+0x282
> 1 12.29 us 12.29 us 12.29 us rwlock:R ep_poll_callback+0x35
> 1 12.02 us 12.02 us 12.02 us rwlock:W do_epoll_ctl+0xb65
> 1 10.25 us 10.25 us 10.25 us rwlock:R ep_poll_callback+0x35
> 1 7.86 us 7.86 us 7.86 us mutex do_epoll_ctl+0x6c1
> 1 5.04 us 5.04 us 5.04 us mutex do_epoll_ctl+0x3d4
>
> Fixes: d783ea8f62c4 ("perf lock contention: Simplify parse_lock_type()")
> Signed-off-by: Chun-Tse Shao <ctshao@...gle.com>
Reviewed-by: Namhyung Kim <namhyung@...nel.org>
Thanks,
Namhyung
> ---
> tools/perf/builtin-lock.c | 64 ++++++++++++++++++++++++---------------
> 1 file changed, 39 insertions(+), 25 deletions(-)
>
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 062e2b56a2ab..7e36bbe3cb80 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -1591,8 +1591,6 @@ static const struct {
> { LCB_F_PERCPU | LCB_F_WRITE, "pcpu-sem:W", "percpu-rwsem" },
> { LCB_F_MUTEX, "mutex", "mutex" },
> { LCB_F_MUTEX | LCB_F_SPIN, "mutex", "mutex" },
> - /* alias for get_type_flag() */
> - { LCB_F_MUTEX | LCB_F_SPIN, "mutex-spin", "mutex" },
> };
>
> static const char *get_type_str(unsigned int flags)
> @@ -1617,19 +1615,6 @@ static const char *get_type_name(unsigned int flags)
> return "unknown";
> }
>
> -static unsigned int get_type_flag(const char *str)
> -{
> - for (unsigned int i = 0; i < ARRAY_SIZE(lock_type_table); i++) {
> - if (!strcmp(lock_type_table[i].name, str))
> - return lock_type_table[i].flags;
> - }
> - for (unsigned int i = 0; i < ARRAY_SIZE(lock_type_table); i++) {
> - if (!strcmp(lock_type_table[i].str, str))
> - return lock_type_table[i].flags;
> - }
> - return UINT_MAX;
> -}
> -
> static void lock_filter_finish(void)
> {
> zfree(&filters.types);
> @@ -2350,29 +2335,58 @@ static int parse_lock_type(const struct option *opt __maybe_unused, const char *
> int unset __maybe_unused)
> {
> char *s, *tmp, *tok;
> - int ret = 0;
>
> s = strdup(str);
> if (s == NULL)
> return -1;
>
> for (tok = strtok_r(s, ", ", &tmp); tok; tok = strtok_r(NULL, ", ", &tmp)) {
> - unsigned int flags = get_type_flag(tok);
> + bool found = false;
>
> - if (flags == -1U) {
> - pr_err("Unknown lock flags: %s\n", tok);
> - ret = -1;
> - break;
> + /* `tok` is `str` in `lock_type_table` if it contains ':'. */
> + if (strchr(tok, ':')) {
> + for (unsigned int i = 0; i < ARRAY_SIZE(lock_type_table); i++) {
> + if (!strcmp(lock_type_table[i].str, tok) &&
> + add_lock_type(lock_type_table[i].flags)) {
> + found = true;
> + break;
> + }
> + }
> +
> + if (!found) {
> + pr_err("Unknown lock flags name: %s\n", tok);
> + free(s);
> + return -1;
> + }
> +
> + continue;
> }
>
> - if (!add_lock_type(flags)) {
> - ret = -1;
> - break;
> + /*
> + * Otherwise `tok` is `name` in `lock_type_table`.
> + * Single lock name could contain multiple flags.
> + */
> + for (unsigned int i = 0; i < ARRAY_SIZE(lock_type_table); i++) {
> + if (!strcmp(lock_type_table[i].name, tok)) {
> + if (add_lock_type(lock_type_table[i].flags)) {
> + found = true;
> + } else {
> + free(s);
> + return -1;
> + }
> + }
> }
> +
> + if (!found) {
> + pr_err("Unknown lock name: %s\n", tok);
> + free(s);
> + return -1;
> + }
> +
> }
>
> free(s);
> - return ret;
> + return 0;
> }
>
> static bool add_lock_addr(unsigned long addr)
> --
> 2.47.0.338.g60cca15819-goog
>
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