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[2620:137:e000::1:20]) by mx.google.com with ESMTP id d8-20020aa7d688000000b004fb33bbfa18si4895802edr.130.2023.04.04.05.53.04; Tue, 04 Apr 2023 05:53:28 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=aPtNfhhD; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234936AbjDDMlA (ORCPT + 99 others); Tue, 4 Apr 2023 08:41:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234499AbjDDMk4 (ORCPT ); Tue, 4 Apr 2023 08:40:56 -0400 Received: from mail-ed1-x52c.google.com (mail-ed1-x52c.google.com [IPv6:2a00:1450:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B489AE4A; Tue, 4 Apr 2023 05:40:52 -0700 (PDT) Received: by mail-ed1-x52c.google.com with SMTP id fi11so6525271edb.10; Tue, 04 Apr 2023 05:40:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680612051; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ynSkjWiStdChDNmK6w/UU6qev6e/KMNN2NT7DgiXXHE=; b=aPtNfhhD6HDyNQalImrT+8W73E2NbJu5FXJZWAiY0ChnnI3+bKrQz43eWEd9PNjY/y a7ynjbzXgZuY/TPKpj/LrlPgSsGh6SAUCFZoiM0jv+CQZGg3LhgkVN7GdIXgsuxFJ99i OfDsvIWKmojCZu2z+CQM83ChibNGTU81YOh5vuOIh5vC2Cma05hOIAvUzBoL/SFCNAf2 SGB4hZiESzRvM5sxGhix+BiKDV6ewfWwpCAot0L/CKY7dwvjg4mdde3l6hZXT6qr8vJS P583DMeH/Nxhe7EGxAqbP7n20NtLnHet0dB8E9spE94CthjK/CZYlIIIKhfmI83qlpYA WsYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680612051; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ynSkjWiStdChDNmK6w/UU6qev6e/KMNN2NT7DgiXXHE=; b=YuZVd7Ik8M2dEhIjotqWIBODErKVIPZs4SC2QvEQQc+oZXa/MeA3GZeTJkBt4Pexoa Wry4rd/AfO2dGJx5jfJ8lj/aFEeLC6+coUAkezhAQYI2pXdrZWX9pI0WHQZLd8XR40/S l8oxer0ZxzF9MdUd7rIklNVqqv+ovkSHuZIXMqwfLbMyvq2jYZnegGOe41Zmp2GGBoQL rDGx+1kdkaplc0KcikLubA1njGzDnIk1rhyr/ENZEIjp8UHgXrx70FmRUQRi2atpVo5e /E0FiHPb3M8uE7ORzK9GgEuPNT/wu5sMkF/+moUJVqZddX3ePDZiR3J4DCnmAawFvHZI 5k8Q== X-Gm-Message-State: AAQBX9e4E17oD42AUWx3LhH0ROmFpaPHjZSXq4zPF5ieQbJ4xmVVxC9W azuYpv/Y//r8QjGWnlyaCZS3LYDMKnw= X-Received: by 2002:a17:907:2071:b0:921:5e7b:1c27 with SMTP id qp17-20020a170907207100b009215e7b1c27mr2121888ejb.24.1680612050967; Tue, 04 Apr 2023 05:40:50 -0700 (PDT) Received: from 127.com ([2620:10d:c092:600::2:2b22]) by smtp.gmail.com with ESMTPSA id g8-20020a170906394800b008cafeec917dsm5978851eje.101.2023.04.04.05.40.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Apr 2023 05:40:50 -0700 (PDT) From: Pavel Begunkov To: io-uring@vger.kernel.org Cc: Jens Axboe , asml.silence@gmail.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 01/13] io_uring/rsrc: use non-pcpu refcounts for nodes Date: Tue, 4 Apr 2023 13:39:45 +0100 Message-Id: X-Mailer: git-send-email 2.39.1 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1762250256454816204?= X-GMAIL-MSGID: =?utf-8?q?1762250256454816204?= One problem with the current rsrc infra is that often updates will generates lots of rsrc nodes, each carry pcpu refs. That takes quite a lot of memory, especially if there is a stall, and takes lots of CPU cycles. Only pcpu allocations takes >50 of CPU with a naive benchmark updating files in a loop. Replace pcpu refs with normal refcounting. There is already a hot path avoiding atomics / refs, but following patches will further improve it. Signed-off-by: Pavel Begunkov --- io_uring/rsrc.c | 15 +++++---------- io_uring/rsrc.h | 6 ++++-- 2 files changed, 9 insertions(+), 12 deletions(-) diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index a5ed0ee7c160..1b9b7f98fb7e 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -155,7 +155,7 @@ void io_rsrc_refs_refill(struct io_ring_ctx *ctx) __must_hold(&ctx->uring_lock) { ctx->rsrc_cached_refs += IO_RSRC_REF_BATCH; - percpu_ref_get_many(&ctx->rsrc_node->refs, IO_RSRC_REF_BATCH); + refcount_add(IO_RSRC_REF_BATCH, &ctx->rsrc_node->refs); } static void __io_rsrc_put_work(struct io_rsrc_node *ref_node) @@ -220,13 +220,11 @@ void io_wait_rsrc_data(struct io_rsrc_data *data) void io_rsrc_node_destroy(struct io_rsrc_node *ref_node) { - percpu_ref_exit(&ref_node->refs); kfree(ref_node); } -static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref) +__cold void io_rsrc_node_ref_zero(struct io_rsrc_node *node) { - struct io_rsrc_node *node = container_of(ref, struct io_rsrc_node, refs); struct io_ring_ctx *ctx = node->rsrc_data->ctx; unsigned long flags; bool first_add = false; @@ -269,11 +267,7 @@ static struct io_rsrc_node *io_rsrc_node_alloc(void) if (!ref_node) return NULL; - if (percpu_ref_init(&ref_node->refs, io_rsrc_node_ref_zero, - 0, GFP_KERNEL)) { - kfree(ref_node); - return NULL; - } + refcount_set(&ref_node->refs, 1); INIT_LIST_HEAD(&ref_node->node); INIT_LIST_HEAD(&ref_node->rsrc_list); ref_node->done = false; @@ -298,7 +292,8 @@ void io_rsrc_node_switch(struct io_ring_ctx *ctx, spin_unlock_irq(&ctx->rsrc_ref_lock); atomic_inc(&data_to_kill->refs); - percpu_ref_kill(&rsrc_node->refs); + /* put master ref */ + io_rsrc_put_node(rsrc_node, 1); ctx->rsrc_node = NULL; } diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h index f27f4975217d..1467b31843bc 100644 --- a/io_uring/rsrc.h +++ b/io_uring/rsrc.h @@ -37,7 +37,7 @@ struct io_rsrc_data { }; struct io_rsrc_node { - struct percpu_ref refs; + refcount_t refs; struct list_head node; struct list_head rsrc_list; struct io_rsrc_data *rsrc_data; @@ -54,6 +54,7 @@ struct io_mapped_ubuf { }; void io_rsrc_put_tw(struct callback_head *cb); +void io_rsrc_node_ref_zero(struct io_rsrc_node *node); void io_rsrc_put_work(struct work_struct *work); void io_rsrc_refs_refill(struct io_ring_ctx *ctx); void io_wait_rsrc_data(struct io_rsrc_data *data); @@ -109,7 +110,8 @@ int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg, static inline void io_rsrc_put_node(struct io_rsrc_node *node, int nr) { - percpu_ref_put_many(&node->refs, nr); + if (refcount_sub_and_test(nr, &node->refs)) + io_rsrc_node_ref_zero(node); } static inline void io_req_put_rsrc(struct io_kiocb *req)