From patchwork Fri Aug 26 02:44:22 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 12955483 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1DD2ECAAD1 for ; Fri, 26 Aug 2022 02:45:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235416AbiHZCpE (ORCPT ); Thu, 25 Aug 2022 22:45:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244846AbiHZCpD (ORCPT ); Thu, 25 Aug 2022 22:45:03 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 229041835A for ; Thu, 25 Aug 2022 19:45:02 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id p9-20020a17090a2d8900b001fb86ec43aaso293467pjd.0 for ; Thu, 25 Aug 2022 19:45:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=PaPuYu1jW6l30jyUgEzf6fCeC16QOg08yHB4Ew2HdVM=; b=GRWpSaM70EZmvKMlFNvW71O+vyfhIii8KVD3IfMCQDb8TiWvtRl//AZ0NMAoAnkp52 lCPxgH8uRmBE7iuNdblxsUTzr7XnprwwQjuPsDEZL2N9jm1C53QVEzWXezafTMsByITm 0MHH6PmJRDm1vOWc76ZZ/IprpTh2GBWLqeDp3HNMbXLUh7shyvKYYYWnqKuKU95tGXWY gufIxRKVaOfKTpoqxebuo+OYy+AZ8LDWxoZ6QPFjF73r5Ljl9f8+nn/N1HNXc31xx52/ dECetY7+9Fmelb70kDDTVQh9MGPbJ8LK4ubKuMnUws8UqnwmbIyhAxbTElaqiIMWFrN3 MMwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=PaPuYu1jW6l30jyUgEzf6fCeC16QOg08yHB4Ew2HdVM=; b=rQydIk0L+2OayCHBcea5f0dHf0AtHrcKH/KhDl+63Vd1UPi7z71eCTuZ9ugGnq6nTL UoNyQMCZFeYNPnNJiU4UF8rQ/9WtP1ZFyakQOa1qI564zdMxn3OurqQoWQQBrtC46lj4 1LOIBAmNz7qvhg7JfCs6PQTsysFU9745h4MY5txpe8KPj/xAW//pT7BmzfW9UgzYDY3l Q+IT3eij++lcBqm4J2g8/ALw8O+duPnxXwkiNPgqFv4wX/LrmMn35Yy0eeDxvWIzUwiN U3gaWgh+auEm+dPu7CCKOBjCM1Ku1GOqbzncMiToxeCiXLVnXk8dUNPqHhc3ix1xUhCc biAg== X-Gm-Message-State: ACgBeo3ONW6pysW75d1vc04TVOm7jZzrrn+4RQYmTzHzbU9EgYZuIZBc yVu0eBemJa/9XvS7ufex/SA= X-Google-Smtp-Source: AA6agR5R7JS+PwvjO3raqPgX79bYewUm8RfaJcq/kT1isr5WF/WqZYncmh5vmqWXfYf/7p1jNenqbA== X-Received: by 2002:a17:90a:de96:b0:1fa:e427:e18e with SMTP id n22-20020a17090ade9600b001fae427e18emr2152653pjv.116.1661481901540; Thu, 25 Aug 2022 19:45:01 -0700 (PDT) Received: from macbook-pro-3.dhcp.thefacebook.com ([2620:10d:c090:400::5:15dc]) by smtp.gmail.com with ESMTPSA id k6-20020a170902ce0600b0015e8d4eb1dbsm292164plg.37.2022.08.25.19.45.00 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 25 Aug 2022 19:45:01 -0700 (PDT) From: Alexei Starovoitov To: davem@davemloft.net Cc: daniel@iogearbox.net, andrii@kernel.org, tj@kernel.org, memxor@gmail.com, delyank@fb.com, linux-mm@kvack.org, bpf@vger.kernel.org, kernel-team@fb.com Subject: [PATCH v4 bpf-next 07/15] bpf: Optimize call_rcu in non-preallocated hash map. Date: Thu, 25 Aug 2022 19:44:22 -0700 Message-Id: <20220826024430.84565-8-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220826024430.84565-1-alexei.starovoitov@gmail.com> References: <20220826024430.84565-1-alexei.starovoitov@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov Doing call_rcu() million times a second becomes a bottle neck. Convert non-preallocated hash map from call_rcu to SLAB_TYPESAFE_BY_RCU. The rcu critical section is no longer observed for one htab element which makes non-preallocated hash map behave just like preallocated hash map. The map elements are released back to kernel memory after observing rcu critical section. This improves 'map_perf_test 4' performance from 100k events per second to 250k events per second. bpf_mem_alloc + percpu_counter + typesafe_by_rcu provide 10x performance boost to non-preallocated hash map and make it within few % of preallocated map while consuming fraction of memory. Acked-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov --- kernel/bpf/hashtab.c | 8 ++++++-- kernel/bpf/memalloc.c | 2 +- tools/testing/selftests/bpf/progs/timer.c | 11 ----------- 3 files changed, 7 insertions(+), 14 deletions(-) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 8f68c6e13339..299ab98f9811 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -940,8 +940,12 @@ static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l) __pcpu_freelist_push(&htab->freelist, &l->fnode); } else { dec_elem_count(htab); - l->htab = htab; - call_rcu(&l->rcu, htab_elem_free_rcu); + if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH) { + l->htab = htab; + call_rcu(&l->rcu, htab_elem_free_rcu); + } else { + htab_elem_free(htab, l); + } } } diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 29f340016e9e..c1817f14c25a 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -277,7 +277,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size) return -ENOMEM; size += LLIST_NODE_SZ; /* room for llist_node */ snprintf(buf, sizeof(buf), "bpf-%u", size); - kmem_cache = kmem_cache_create(buf, size, 8, 0, NULL); + kmem_cache = kmem_cache_create(buf, size, 8, SLAB_TYPESAFE_BY_RCU, NULL); if (!kmem_cache) { free_percpu(pc); return -ENOMEM; diff --git a/tools/testing/selftests/bpf/progs/timer.c b/tools/testing/selftests/bpf/progs/timer.c index 5f5309791649..0053c5402173 100644 --- a/tools/testing/selftests/bpf/progs/timer.c +++ b/tools/testing/selftests/bpf/progs/timer.c @@ -208,17 +208,6 @@ static int timer_cb2(void *map, int *key, struct hmap_elem *val) */ bpf_map_delete_elem(map, key); - /* in non-preallocated hashmap both 'key' and 'val' are RCU - * protected and still valid though this element was deleted - * from the map. Arm this timer for ~35 seconds. When callback - * finishes the call_rcu will invoke: - * htab_elem_free_rcu - * check_and_free_timer - * bpf_timer_cancel_and_free - * to cancel this 35 second sleep and delete the timer for real. - */ - if (bpf_timer_start(&val->timer, 1ull << 35, 0) != 0) - err |= 256; ok |= 4; } return 0;