From patchwork Tue Feb 23 22:28:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12101005 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BABAFC433DB for ; Tue, 23 Feb 2021 22:33:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AE2E64E3F for ; Tue, 23 Feb 2021 22:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232196AbhBWWc2 (ORCPT ); Tue, 23 Feb 2021 17:32:28 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:62322 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232380AbhBWW34 (ORCPT ); Tue, 23 Feb 2021 17:29:56 -0500 Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 11NMPZU3025809 for ; Tue, 23 Feb 2021 14:29:15 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=9MXKxqv+SncBnz5OqxIZYK7jmff9BGIDVI3Ly/9d+n0=; b=YAf1/UwhhkYVTLaabyMoOyVAOteljXxr6GLPokZffR52vmsKy7aAN4yGnLUfWDTqUDyj 9TtPHs3lNq9Thse/tAn/9UFs8jwQwEVdw0afuFFtbjGZKO44osoxB2lkFL+jepilo6b0 HEH/CG2VwI/qCwKHy1mjTRTgATqijBBj9QE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 36ujy7p31g-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 23 Feb 2021 14:29:15 -0800 Received: from intmgw001.38.frc1.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:11d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 23 Feb 2021 14:29:14 -0800 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 7ABA062E093E; Tue, 23 Feb 2021 14:29:10 -0800 (PST) From: Song Liu To: , , CC: , , , , Song Liu , Andrii Nakryiko Subject: [PATCH v5 bpf-next 6/6] bpf: runqslower: use task local storage Date: Tue, 23 Feb 2021 14:28:45 -0800 Message-ID: <20210223222845.2866124-7-songliubraving@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20210223222845.2866124-1-songliubraving@fb.com> References: <20210223222845.2866124-1-songliubraving@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-23_11:2021-02-23,2021-02-23 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 spamscore=0 priorityscore=1501 phishscore=0 adultscore=0 mlxscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 suspectscore=0 impostorscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102230189 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Replace hashtab with task local storage in runqslower. This improves the performance of these BPF programs. The following table summarizes average runtime of these programs, in nanoseconds: task-local hash-prealloc hash-no-prealloc handle__sched_wakeup 125 340 3124 handle__sched_wakeup_new 2812 1510 2998 handle__sched_switch 151 208 991 Note that, task local storage gives better performance than hashtab for handle__sched_wakeup and handle__sched_switch. On the other hand, for handle__sched_wakeup_new, task local storage is slower than hashtab with prealloc. This is because handle__sched_wakeup_new accesses the data for the first time, so it has to allocate the data for task local storage. Once the initial allocation is done, subsequent accesses, as those in handle__sched_wakeup, are much faster with task local storage. If we disable hashtab prealloc, task local storage is much faster for all 3 functions. Acked-by: Andrii Nakryiko Signed-off-by: Song Liu --- tools/bpf/runqslower/runqslower.bpf.c | 33 +++++++++++++++++---------- 1 file changed, 21 insertions(+), 12 deletions(-) diff --git a/tools/bpf/runqslower/runqslower.bpf.c b/tools/bpf/runqslower/runqslower.bpf.c index 1f18a409f0443..645530ca7e985 100644 --- a/tools/bpf/runqslower/runqslower.bpf.c +++ b/tools/bpf/runqslower/runqslower.bpf.c @@ -11,9 +11,9 @@ const volatile __u64 min_us = 0; const volatile pid_t targ_pid = 0; struct { - __uint(type, BPF_MAP_TYPE_HASH); - __uint(max_entries, 10240); - __type(key, u32); + __uint(type, BPF_MAP_TYPE_TASK_STORAGE); + __uint(map_flags, BPF_F_NO_PREALLOC); + __type(key, int); __type(value, u64); } start SEC(".maps"); @@ -25,15 +25,20 @@ struct { /* record enqueue timestamp */ __always_inline -static int trace_enqueue(u32 tgid, u32 pid) +static int trace_enqueue(struct task_struct *t) { - u64 ts; + u32 pid = t->pid; + u64 *ptr; if (!pid || (targ_pid && targ_pid != pid)) return 0; - ts = bpf_ktime_get_ns(); - bpf_map_update_elem(&start, &pid, &ts, 0); + ptr = bpf_task_storage_get(&start, t, 0, + BPF_LOCAL_STORAGE_GET_F_CREATE); + if (!ptr) + return 0; + + *ptr = bpf_ktime_get_ns(); return 0; } @@ -43,7 +48,7 @@ int handle__sched_wakeup(u64 *ctx) /* TP_PROTO(struct task_struct *p) */ struct task_struct *p = (void *)ctx[0]; - return trace_enqueue(p->tgid, p->pid); + return trace_enqueue(p); } SEC("tp_btf/sched_wakeup_new") @@ -52,7 +57,7 @@ int handle__sched_wakeup_new(u64 *ctx) /* TP_PROTO(struct task_struct *p) */ struct task_struct *p = (void *)ctx[0]; - return trace_enqueue(p->tgid, p->pid); + return trace_enqueue(p); } SEC("tp_btf/sched_switch") @@ -70,12 +75,16 @@ int handle__sched_switch(u64 *ctx) /* ivcsw: treat like an enqueue event and store timestamp */ if (prev->state == TASK_RUNNING) - trace_enqueue(prev->tgid, prev->pid); + trace_enqueue(prev); pid = next->pid; + /* For pid mismatch, save a bpf_task_storage_get */ + if (!pid || (targ_pid && targ_pid != pid)) + return 0; + /* fetch timestamp and calculate delta */ - tsp = bpf_map_lookup_elem(&start, &pid); + tsp = bpf_task_storage_get(&start, next, 0, 0); if (!tsp) return 0; /* missed enqueue */ @@ -91,7 +100,7 @@ int handle__sched_switch(u64 *ctx) bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &event, sizeof(event)); - bpf_map_delete_elem(&start, &pid); + bpf_task_storage_delete(&start, next); return 0; }