From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 15559C5519F for ; Tue, 17 Nov 2020 19:07:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A717824181 for ; Tue, 17 Nov 2020 19:07:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XoZH8GpC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726315AbgKQTHd (ORCPT ); Tue, 17 Nov 2020 14:07:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725613AbgKQTHc (ORCPT ); Tue, 17 Nov 2020 14:07:32 -0500 Received: from mail-ot1-x343.google.com (mail-ot1-x343.google.com [IPv6:2607:f8b0:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 979A6C0613CF; Tue, 17 Nov 2020 11:07:31 -0800 (PST) Received: by mail-ot1-x343.google.com with SMTP id 79so20494733otc.7; Tue, 17 Nov 2020 11:07:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-transfer-encoding; bh=9fgySF6K68SlluAGbdqXKQeVrDTrhLPgdEXfhoFPwX8=; b=XoZH8GpCCWfsU+IoFOA00/Zk5jH4C2i3Xv8NjBnsgNDw7x87/1ZRrXEnh0/DTnx7wd yT4rS+fQosOlWkWUSSMb1S4wkcVmamnYgFHuDu+G/giPJGRAsEvHsBx7aVrSHf5yeLVu GBn6DveQkZ/WKVf5bLD0LGrYI2s6h7faYVGbrZOzbMxeD2SFxmwpCH44B7bKQL27z8lM 4VyzAdV4V/XemAMsQJDh5Q7eGlNMtjqaKFguAlWJbNYkAq4bEzyjuhhwosv4+ZzhO6wF HCO6gKEQhTZ5pIeZJVxN2Vn6vy4SOFRsUhT86MkV/l7NJpIMMFVDTEo3sSFAwVce/39L rHGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-transfer-encoding; bh=9fgySF6K68SlluAGbdqXKQeVrDTrhLPgdEXfhoFPwX8=; b=Np/jbq0WWkammvnLB6pZDxb6dClUk+72TTw/IQHjwdql20/CvApxxyRIvrdiINbD8f IFbmA48Czz2SmODiUO/rEuIQ9WIcPQhjw5tgD1W0LDCV8fy8kkjZDU7L3oHwf5RxDULK kSrNddeSh8utcFMcg3Us8rQuqqiBwVjAqQ2AsaYneL8D2uOVbwWXetwO/TXfFVG7WyCh AakSagYtB3VIYrqYtl2Ui8t3nwpANJoqx7yN0gerMBBYoHsOj8YoiQB82uhpQgqcY/E6 VYGbj3SN3XgPUQMqfMIPtrKvdCBuYEOZWljBHFnAA/2CCEhGh5DhQySBSFVxBTDwsMIY t7IA== X-Gm-Message-State: AOAM533FcA8PxdnJtGkQkpz0A2hUcmoHjFWQvVcL4XPjAJVJ5Xkv7O+u l3tPG5n9MvY/XT1iiFH3WXvKV4C/l8KD1g== X-Google-Smtp-Source: ABdhPJyvLHJlKU9g2W718K3p65afXZsjKc8wVd1jMSWIOnG1FdT8bzA4YxQmeyGQS90q+L6HzaBBUg== X-Received: by 2002:a9d:460a:: with SMTP id y10mr3761572ote.99.1605640050975; Tue, 17 Nov 2020 11:07:30 -0800 (PST) Received: from localhost ([184.63.162.180]) by smtp.gmail.com with ESMTPSA id w22sm1804563oie.49.2020.11.17.11.07.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Nov 2020 11:07:30 -0800 (PST) Date: Tue, 17 Nov 2020 11:07:22 -0800 From: John Fastabend To: Magnus Karlsson , magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, jonathan.lemon@gmail.com, kuba@kernel.org, john.fastabend@gmail.com Cc: bpf@vger.kernel.org, jeffrey.t.kirsher@intel.com, anthony.l.nguyen@intel.com, maciej.fijalkowski@intel.com, maciejromanfijalkowski@gmail.com, intel-wired-lan@lists.osuosl.org Message-ID: <5fb41f6ae195_310220813@john-XPS-13-9370.notmuch> In-Reply-To: <1605525167-14450-5-git-send-email-magnus.karlsson@gmail.com> References: <1605525167-14450-1-git-send-email-magnus.karlsson@gmail.com> <1605525167-14450-5-git-send-email-magnus.karlsson@gmail.com> Subject: RE: [PATCH bpf-next v3 4/5] xsk: introduce batched Tx descriptor interfaces Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Magnus Karlsson wrote: > From: Magnus Karlsson > > Introduce batched descriptor interfaces in the xsk core code for the > Tx path to be used in the driver to write a code path with higher > performance. This interface will be used by the i40e driver in the > next patch. Though other drivers would likely benefit from this new > interface too. > > Note that batching is only implemented for the common case when > there is only one socket bound to the same device and queue id. When > this is not the case, we fall back to the old non-batched version of > the function. > > Signed-off-by: Magnus Karlsson > --- > include/net/xdp_sock_drv.h | 7 ++++ > net/xdp/xsk.c | 57 +++++++++++++++++++++++++++++ > net/xdp/xsk_queue.h | 89 +++++++++++++++++++++++++++++++++++++++------- > 3 files changed, 140 insertions(+), 13 deletions(-) > Acked-by: John Fastabend > + > +u32 xsk_tx_peek_release_desc_batch(struct xsk_buff_pool *pool, struct xdp_desc *descs, > + u32 max_entries) > +{ > + struct xdp_sock *xs; > + u32 nb_pkts; > + > + rcu_read_lock(); > + if (!list_is_singular(&pool->xsk_tx_list)) { > + /* Fallback to the non-batched version */ I'm going to ask even though I believe its correct. If we fallback here and then an entry is added to the list while we are in the fallback logic everything should still be OK, correct? > + rcu_read_unlock(); > + return xsk_tx_peek_release_fallback(pool, descs, max_entries); > + } > + > + xs = list_first_or_null_rcu(&pool->xsk_tx_list, struct xdp_sock, tx_list); > + if (!xs) { > + nb_pkts = 0; > + goto out; > + } > + > + nb_pkts = xskq_cons_peek_desc_batch(xs->tx, descs, pool, max_entries); > + if (!nb_pkts) { > + xs->tx->queue_empty_descs++; > + goto out; > + } > + > + /* This is the backpressure mechanism for the Tx path. Try to > + * reserve space in the completion queue for all packets, but > + * if there are fewer slots available, just process that many > + * packets. This avoids having to implement any buffering in > + * the Tx path. > + */ > + nb_pkts = xskq_prod_reserve_addr_batch(pool->cq, descs, nb_pkts); > + if (!nb_pkts) > + goto out; > + > + xskq_cons_release_n(xs->tx, nb_pkts); > + __xskq_cons_release(xs->tx); > + xs->sk.sk_write_space(&xs->sk); > + > +out: > + rcu_read_unlock(); > + return nb_pkts; > +} > +EXPORT_SYMBOL(xsk_tx_peek_release_desc_batch); > +