From nobody Fri Nov 29 19:36:15 2024 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4214FDDA1; Mon, 16 Sep 2024 01:53:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726451633; cv=none; b=l1LuJdByIw5w0H21dwLrO1D6pr1LimYu1feVnUeB6DUOb1XKC2KKKuQL64+FD8CWDTpLnYiBEw2G39LsYv6X75MPlfkzsWbOx/B7lW78q0azpm7+qCx1qaVlKRta8Ifd04sCk63uVOLh4C72/I4Y6dv+QuJjg7V97bZr6QUyoG8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726451633; c=relaxed/simple; bh=DUxM5maq4XgUzTNsy2M1HkShE00z3cLiVMLDDlMXzgk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=QISkN+6ifo24Dg1eUHS0l+yhj66BsLekcO5dG8Cw+H3Ly6nrCb9b8S5hlevqQGc/DQrH4xC9iD87tPUNuPHu5cOZ2xxMBCN2GoivQwI9EyLmxjxsmzfrv9owBm/wrFHYufLisFFURQybY5fm/lHG8WhQGNqXkEaEzkflqcLOg3E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4X6ScV03Gbz4f3jZ1; Mon, 16 Sep 2024 09:53:30 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id CE6901A08DC; Mon, 16 Sep 2024 09:53:40 +0800 (CST) Received: from huawei.com (unknown [10.67.174.45]) by APP4 (Coremail) with SMTP id gCh0CgCXy8eZj+dmP_LGBQ--.63146S3; Mon, 16 Sep 2024 09:53:40 +0800 (CST) From: Tengda Wu To: Peter Zijlstra , Namhyung Kim Cc: song@kernel.org, Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH -next v3 1/2] perf stat: Support inherit events during fork() for bperf Date: Mon, 16 Sep 2024 01:43:17 +0000 Message-Id: <20240916014318.267709-2-wutengda@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240916014318.267709-1-wutengda@huaweicloud.com> References: <20240916014318.267709-1-wutengda@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgCXy8eZj+dmP_LGBQ--.63146S3 X-Coremail-Antispam: 1UD129KBjvJXoW3Ar1kGFW7GrWDtF4rJF1UZFb_yoWfWFykpF 43C34vkrWFq3y7Wwn8Xw4kGr1Sv34xu3y5WFn5K3yftF1kJr93Ka4xKFWUt3W3Gr4DCFyS qF1jgw4UJ39rX3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPFb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUGw A2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW7JVWDJwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMc Ij6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_ Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2AFwI 0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG 67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MI IYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E 14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxU2HGQ DUUUU X-CM-SenderInfo: pzxwv0hjgdqx5xdzvxpfor3voofrz/ Content-Type: text/plain; charset="utf-8" bperf has a nice ability to share PMUs, but it still does not support inherit events during fork(), resulting in some deviations in its stat results compared with perf. perf stat result: $ ./perf stat -e cycles,instructions -- ./perf test -w sqrtloop Performance counter stats for './perf test -w sqrtloop': 2,316,038,116 cycles 2,859,350,725 instructions 1.009603637 seconds time elapsed 1.004196000 seconds user 0.003950000 seconds sys bperf stat result: $ ./perf stat --bpf-counters -e cycles,instructions -- \ ./perf test -w sqrtloop Performance counter stats for './perf test -w sqrtloop': 18,762,093 cycles 23,487,766 instructions 1.008913769 seconds time elapsed 1.003248000 seconds user 0.004069000 seconds sys In order to support event inheritance, two new bpf programs are added to monitor the fork and exit of tasks respectively. When a task is created, add it to the filter map to enable counting, and reuse the `accum_key` of its parent task to count together with the parent task. When a task exits, remove it from the filter map to disable counting. After support: $ ./perf stat --bpf-counters -e cycles,instructions -- \ ./perf test -w sqrtloop Performance counter stats for './perf test -w sqrtloop': 2,316,252,189 cycles 2,859,946,547 instructions 1.009422314 seconds time elapsed 1.003597000 seconds user 0.004270000 seconds sys Signed-off-by: Tengda Wu --- tools/perf/util/bpf_counter.c | 32 +++++-- tools/perf/util/bpf_skel/bperf_follower.bpf.c | 87 +++++++++++++++++-- tools/perf/util/bpf_skel/bperf_u.h | 5 ++ 3 files changed, 111 insertions(+), 13 deletions(-) diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c index 7a8af60e0f51..94aa46f50052 100644 --- a/tools/perf/util/bpf_counter.c +++ b/tools/perf/util/bpf_counter.c @@ -394,6 +394,7 @@ static int bperf_check_target(struct evsel *evsel, } =20 static struct perf_cpu_map *all_cpu_map; +static __u32 filter_entry_cnt; =20 static int bperf_reload_leader_program(struct evsel *evsel, int attr_map_f= d, struct perf_event_attr_map_entry *entry) @@ -444,12 +445,31 @@ static int bperf_reload_leader_program(struct evsel *= evsel, int attr_map_fd, return err; } =20 +/* Attach programs on demand according to filter types to reduce overhead = */ +static int bperf_attach_follower_program(struct bperf_follower_bpf *skel, + enum bperf_filter_type filter_type) +{ + struct bpf_link *link; + int err =3D 0; + + if (filter_type =3D=3D BPERF_FILTER_PID || + filter_type =3D=3D BPERF_FILTER_TGID) + err =3D bperf_follower_bpf__attach(skel); + else { + link =3D bpf_program__attach(skel->progs.fexit_XXX); + if (IS_ERR(link)) + err =3D PTR_ERR(link); + } + + return err; +} + static int bperf__load(struct evsel *evsel, struct target *target) { struct perf_event_attr_map_entry entry =3D {0xffffffff, 0xffffffff}; int attr_map_fd, diff_map_fd =3D -1, err; enum bperf_filter_type filter_type; - __u32 filter_entry_cnt, i; + __u32 i; =20 if (bperf_check_target(evsel, target, &filter_type, &filter_entry_cnt)) return -1; @@ -529,9 +549,6 @@ static int bperf__load(struct evsel *evsel, struct targ= et *target) /* set up reading map */ bpf_map__set_max_entries(evsel->follower_skel->maps.accum_readings, filter_entry_cnt); - /* set up follower filter based on target */ - bpf_map__set_max_entries(evsel->follower_skel->maps.filter, - filter_entry_cnt); err =3D bperf_follower_bpf__load(evsel->follower_skel); if (err) { pr_err("Failed to load follower skeleton\n"); @@ -543,6 +560,7 @@ static int bperf__load(struct evsel *evsel, struct targ= et *target) for (i =3D 0; i < filter_entry_cnt; i++) { int filter_map_fd; __u32 key; + struct bperf_filter_value fval =3D { i, 0 }; =20 if (filter_type =3D=3D BPERF_FILTER_PID || filter_type =3D=3D BPERF_FILTER_TGID) @@ -553,12 +571,12 @@ static int bperf__load(struct evsel *evsel, struct ta= rget *target) break; =20 filter_map_fd =3D bpf_map__fd(evsel->follower_skel->maps.filter); - bpf_map_update_elem(filter_map_fd, &key, &i, BPF_ANY); + bpf_map_update_elem(filter_map_fd, &key, &fval, BPF_ANY); } =20 evsel->follower_skel->bss->type =3D filter_type; =20 - err =3D bperf_follower_bpf__attach(evsel->follower_skel); + err =3D bperf_attach_follower_program(evsel->follower_skel, filter_type); =20 out: if (err && evsel->bperf_leader_link_fd >=3D 0) @@ -623,7 +641,7 @@ static int bperf__read(struct evsel *evsel) bperf_sync_counters(evsel); reading_map_fd =3D bpf_map__fd(skel->maps.accum_readings); =20 - for (i =3D 0; i < bpf_map__max_entries(skel->maps.accum_readings); i++) { + for (i =3D 0; i < filter_entry_cnt; i++) { struct perf_cpu entry; __u32 cpu; =20 diff --git a/tools/perf/util/bpf_skel/bperf_follower.bpf.c b/tools/perf/uti= l/bpf_skel/bperf_follower.bpf.c index f193998530d4..e804b2a9d0a6 100644 --- a/tools/perf/util/bpf_skel/bperf_follower.bpf.c +++ b/tools/perf/util/bpf_skel/bperf_follower.bpf.c @@ -5,6 +5,8 @@ #include #include "bperf_u.h" =20 +#define MAX_ENTRIES 102400 + struct { __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); __uint(key_size, sizeof(__u32)); @@ -22,7 +24,9 @@ struct { struct { __uint(type, BPF_MAP_TYPE_HASH); __uint(key_size, sizeof(__u32)); - __uint(value_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bperf_filter_value)); + __uint(max_entries, MAX_ENTRIES); + __uint(map_flags, BPF_F_NO_PREALLOC); } filter SEC(".maps"); =20 enum bperf_filter_type type =3D 0; @@ -33,14 +37,15 @@ int BPF_PROG(fexit_XXX) { struct bpf_perf_event_value *diff_val, *accum_val; __u32 filter_key, zero =3D 0; - __u32 *accum_key; + __u32 accum_key; + struct bperf_filter_value *fval; =20 if (!enabled) return 0; =20 switch (type) { case BPERF_FILTER_GLOBAL: - accum_key =3D &zero; + accum_key =3D zero; goto do_add; case BPERF_FILTER_CPU: filter_key =3D bpf_get_smp_processor_id(); @@ -55,16 +60,20 @@ int BPF_PROG(fexit_XXX) return 0; } =20 - accum_key =3D bpf_map_lookup_elem(&filter, &filter_key); - if (!accum_key) + fval =3D bpf_map_lookup_elem(&filter, &filter_key); + if (!fval) return 0; =20 + accum_key =3D fval->accum_key; + if (fval->exited) + bpf_map_delete_elem(&filter, &filter_key); + do_add: diff_val =3D bpf_map_lookup_elem(&diff_readings, &zero); if (!diff_val) return 0; =20 - accum_val =3D bpf_map_lookup_elem(&accum_readings, accum_key); + accum_val =3D bpf_map_lookup_elem(&accum_readings, &accum_key); if (!accum_val) return 0; =20 @@ -75,4 +84,70 @@ int BPF_PROG(fexit_XXX) return 0; } =20 +/* The program is only used for PID or TGID filter types. */ +SEC("tp_btf/task_newtask") +int BPF_PROG(on_newtask, struct task_struct *task, __u64 clone_flags) +{ + __u32 parent_key, child_key; + struct bperf_filter_value *parent_fval; + struct bperf_filter_value child_fval =3D { 0 }; + + if (!enabled) + return 0; + + switch (type) { + case BPERF_FILTER_PID: + parent_key =3D bpf_get_current_pid_tgid() & 0xffffffff; + child_key =3D task->pid; + break; + case BPERF_FILTER_TGID: + parent_key =3D bpf_get_current_pid_tgid() >> 32; + child_key =3D task->tgid; + if (child_key =3D=3D parent_key) + return 0; + break; + default: + return 0; + } + + /* Check if the current task is one of the target tasks to be counted */ + parent_fval =3D bpf_map_lookup_elem(&filter, &parent_key); + if (!parent_fval) + return 0; + + /* Start counting for the new task by adding it into filter map, + * inherit the accum key of its parent task so that they can be + * counted together. + */ + child_fval.accum_key =3D parent_fval->accum_key; + child_fval.exited =3D 0; + bpf_map_update_elem(&filter, &child_key, &child_fval, BPF_NOEXIST); + + return 0; +} + +/* The program is only used for PID or TGID filter types. */ +SEC("tp_btf/sched_process_exit") +int BPF_PROG(on_exittask, struct task_struct *task) +{ + __u32 pid; + struct bperf_filter_value *fval; + + if (!enabled) + return 0; + + /* Stop counting for this task by removing it from filter map. + * For TGID type, if the pid can be found in the map, it means that + * this pid belongs to the leader task. After the task exits, the + * tgid of its child tasks (if any) will be 1, so the pid can be + * safely removed. + */ + pid =3D task->pid; + fval =3D bpf_map_lookup_elem(&filter, &pid); + if (fval) + fval->exited =3D 1; + + return 0; +} + char LICENSE[] SEC("license") =3D "Dual BSD/GPL"; diff --git a/tools/perf/util/bpf_skel/bperf_u.h b/tools/perf/util/bpf_skel/= bperf_u.h index 1ce0c2c905c1..4a4a753980be 100644 --- a/tools/perf/util/bpf_skel/bperf_u.h +++ b/tools/perf/util/bpf_skel/bperf_u.h @@ -11,4 +11,9 @@ enum bperf_filter_type { BPERF_FILTER_TGID, }; =20 +struct bperf_filter_value { + __u32 accum_key; + __u8 exited; +}; + #endif /* __BPERF_STAT_U_H */ --=20 2.34.1 From nobody Fri Nov 29 19:36:15 2024 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E038DDAD; Mon, 16 Sep 2024 01:53:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726451634; cv=none; b=HdoPj4oh/AkNCT47pSYu/TpkYITkE0atmUfuKFMx288qIvn/XL756mOy4q2j+dDM4Vb6kuKu96jwvzstwHWlxHvl+JuirlfPyHPiDV7x8WJqM9Oiq5wx4V1TFpoNKfXiq4Y+1nhY1U4XcBdy8CkEz4LLQtd3t2F+1CRrPCYEbBU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726451634; c=relaxed/simple; bh=iq25zN/1fAllIBHLNn/L+clDUrU36h3yvFzfKev23wM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=lHhT7RH3XDzQGbuOifaNq45NqQQWt6rGUsS253bbhFycx4PKxdCs5kQd+k/VJE4x9WqIMWUuy8pmaPFEL58gmAAaDFhm965nZtxox4UdomtF/UK8NnM1vfWMxU2xWI3/omicIJW72syEGSGe9cO2enAwMolXXlOVqp/qm3gma0M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4X6ScP2KBqz4f3jHx; Mon, 16 Sep 2024 09:53:25 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id C56331A0359; Mon, 16 Sep 2024 09:53:41 +0800 (CST) Received: from huawei.com (unknown [10.67.174.45]) by APP4 (Coremail) with SMTP id gCh0CgCXy8eZj+dmP_LGBQ--.63146S4; Mon, 16 Sep 2024 09:53:41 +0800 (CST) From: Tengda Wu To: Peter Zijlstra , Namhyung Kim Cc: song@kernel.org, Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH -next v3 2/2] perf test: Use sqrtloop workload to test bperf event Date: Mon, 16 Sep 2024 01:43:18 +0000 Message-Id: <20240916014318.267709-3-wutengda@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240916014318.267709-1-wutengda@huaweicloud.com> References: <20240916014318.267709-1-wutengda@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgCXy8eZj+dmP_LGBQ--.63146S4 X-Coremail-Antispam: 1UD129KBjvdXoW7Jr47AFyktw13CrW8Zw18Xwb_yoW3AFg_GF WxXrn7tw4fA3srtrn5Kan5Ar1xXrWfZFykGr1rWF13C390kFy5GFyDZr98A34rWws3t393 Wwn7tr1Sya17KjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbDAYFVCjjxCrM7AC8VAFwI0_Wr0E3s1l1xkIjI8I6I8E6xAIw20E Y4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l82xGYIkIc2x26280x7IE14v26r15M2 8IrcIa0xkI8VCY1x0267AKxVW5JVCq3wA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK 021l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r 4UJVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx 0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWU JVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7AKxV WUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E 14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIx kGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAF wI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r 4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UCZXrU UUUU= X-CM-SenderInfo: pzxwv0hjgdqx5xdzvxpfor3voofrz/ Content-Type: text/plain; charset="utf-8" Replace `brstack` workload with `sqrtloop` workload, because `sqrtloop` workload contains fork(), which is suitable for testing the bperf event inheritance feature. Signed-off-by: Tengda Wu --- tools/perf/tests/shell/stat_bpf_counters.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/tests/shell/stat_bpf_counters.sh b/tools/perf/tests= /shell/stat_bpf_counters.sh index f250b7d6f773..831f02add75e 100755 --- a/tools/perf/tests/shell/stat_bpf_counters.sh +++ b/tools/perf/tests/shell/stat_bpf_counters.sh @@ -4,7 +4,7 @@ =20 set -e =20 -workload=3D"perf test -w brstack" +workload=3D"perf test -w sqrtloop" =20 # check whether $2 is within +/- 20% of $1 compare_number() --=20 2.34.1