From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id CF0B7489F8; Tue, 28 Oct 2025 14:40:35 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 96E4E4028D; Tue, 28 Oct 2025 14:40:35 +0100 (CET) Received: from mail-pj1-f47.google.com (mail-pj1-f47.google.com [209.85.216.47]) by mails.dpdk.org (Postfix) with ESMTP id 2CDAC4021E for ; Tue, 28 Oct 2025 14:40:34 +0100 (CET) Received: by mail-pj1-f47.google.com with SMTP id 98e67ed59e1d1-33d463e79ddso7467921a91.0 for ; Tue, 28 Oct 2025 06:40:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20230601.gappssmtp.com; s=20230601; t=1761658833; x=1762263633; darn=dpdk.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=vx1x4QsjlP2N5UfkVAHNhtTlL8DSe9FLES9dXmO1ZEE=; b=F+O4G2eu7oVDPQOZ5PrYQ6XPpiLztmBpLuPgUFX/qRii6/NKy9xjgFO1syhLEn/veM 0wz3tZ/hM0+4G0or20gHsodbzM/wwLO+a2S8T7ak0TsR3+1v7jTl//10vDPL2/0t0ncy RDdwccL36dI0v4JPZXat1YZ+HTIx+wQzo8R7zgjOoTqkcjmmwU+Izk3BatXDmUp4lFXX cZ4jQsTkLgPjWNA1U+7/H1axjM8LDYWV5eFpl/27Et9qXxmmDjb9Ec+wgTvTxP3VcmrX jDAEwynLtkj2OSpLE8MuQGTK8ZlLtPvBzNA7tlYD99Qmg5XrMjZtx5FL3Ft7uDi2IYyk V68Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761658833; x=1762263633; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=vx1x4QsjlP2N5UfkVAHNhtTlL8DSe9FLES9dXmO1ZEE=; b=E9g53n8tj30Boj8WlNJybWKSyrNij4k/CdtlO/MDUxn+gJCQIjiwUFUbAjk9C0H9fl HM9lAYGS92e/KlglY0y0LMgPFQHQ0vODDKPAzUYl4E8ihCDulmPOIJ7ffEDZj3cd32+t WsBVgyB+RaEYB5M3w8Z5MsyzpX3ZF1AmEY/D9Pknhog3vAIB2cNiRmG3XqP0pSnjXwQe qAcpeKnzPegaDFXArT5wOtFH0l+4dmKGTGYFF5Pgevtey6H3rlFMHv6QULlqf0VqNr+8 6yLimjVCw7wrMmWX0Mm4agBJnpjNMsTl5Bk9HxUfxZQmBSTHIZ4PlaOWMeUA+3YaI7GR bbEw== X-Gm-Message-State: AOJu0YyRkRPAMLKfDiGK4rRGOnGbhoIyFyJ4/nlIgo1CJ19e4/pMQIQI 1GAESB47TDOUDZbfyqWV8q3dWtA4AGwNhDtY4a7mAqVbQtmlZzrpmelMlzMtpc6fYNRp3jWfKg8 qEl7bEBw= X-Gm-Gg: ASbGncu4M3a6S9evIcVRklL1Ipt2Cwb2lbvcaUDae8N/Gtc1RNrsiaZQ7FbANwyyYJH NGl0PlrC7e+/3Gmiyc4iINpyYcVEbPMr9E+GErGl1RoFlUAdwRCUQwOo/1/2+c/0DNyW3HhdUnJ aR+7AAPF2PkGzT3Vnpj4A3KnVV6h20AxXT74AK4JdArqVfzcTggNPanRnPQzsoVaFF3VL7YBJAh HTUj9ySurw4GqUjgWg4HIZi8QlpCqa4V2UuJHwL5Oiw4maUdtG5Fd0Dt4Hz4tUdfOWH3AdE7Sbq NmKWp3PbeawBe131rHUdogt8JRkO4KZ7oBG1yJ7hfmbEGLpnfpa5HMjPg0/4xX0RZf4ZpQgWrQm DGSidcCaymzFM/j7dtswIlQcNpce8+HbO012QaozCQlr/KpOv2oPvhB0f7HPp4L9zX3KIJ+M70M UCJaHspm90oBT8Z94AmNm0mZ9R0mzsEzKVug== X-Google-Smtp-Source: AGHT+IFKx88kuiopsKb2MoyJDjTdAEKGEw0I7dOvZ8Ik/CXnjB+JQPFWLNZ317EgfG5m2nR8AvcxCw== X-Received: by 2002:a17:90a:c2c8:b0:32e:7270:9499 with SMTP id 98e67ed59e1d1-340276009famr4021338a91.0.1761658832885; Tue, 28 Oct 2025 06:40:32 -0700 (PDT) Received: from phoenix (204-195-96-226.wavecable.com. [204.195.96.226]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b7128884e0asm10689733a12.16.2025.10.28.06.40.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Oct 2025 06:40:32 -0700 (PDT) Date: Tue, 28 Oct 2025 06:40:30 -0700 From: Stephen Hemminger To: Wencheng Li Cc: dev@dpdk.org Subject: Re: [PATCH v11 2/3] net/macb: add NEON vectorized Rx/Tx Message-ID: <20251028064030.6ffe334c@phoenix> In-Reply-To: <1761640350-80578-1-git-send-email-liwencheng@phytium.com.cn> References: <1755664435-9462-1-git-send-email-liwencheng@phytium.com.cn> <1761640350-80578-1-git-send-email-liwencheng@phytium.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Tue, 28 Oct 2025 08:32:30 +0000 Wencheng Li wrote: > +static inline uint8x8_t macb_mbuf_initializer(struct macb_rx_queue *rxq) > +{ > + uint64x1_t mbuf_initializer; > + uint8x8_t rearm_data_vec; > + volatile struct rte_mbuf mbuf = { > + .buf_addr = 0, > + .data_off = RTE_PKTMBUF_HEADROOM + MACB_RX_DATA_OFFSET, > + .nb_segs = 1, > + .port = rxq->port_id, > + }; > + > + mbuf_initializer = vdup_n_u64(0); > + rte_atomic_store_explicit(&mbuf.refcnt, 1, rte_memory_order_relaxed); > + > + /* prevent compiler reordering: rearm_data covers previous fields */ > + rte_compiler_barrier(); > + mbuf_initializer = > + vset_lane_u64(*(volatile uint64_t *)(&mbuf.rearm_data), mbuf_initializer, 0); Why is a variable on stack marked volatile. My understanding is that volatile is for cases where data is accessed from two contexts (threads or signals). This is not the case for on-stack variable. The compiler barrier should be enough protection to prevent reordering. And setting same variable twice seems wrong as well.