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[204.195.96.226]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b712d024aaasm5093919a12.26.2025.10.26.11.17.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Oct 2025 11:17:33 -0700 (PDT) Date: Sun, 26 Oct 2025 11:17:31 -0700 From: Stephen Hemminger To: liwencheng Cc: dev@dpdk.org Subject: Re: [PATCH v4 3/4] net/macb: add NEON vectorized Rx/Tx Message-ID: <20251026111731.66acce34@phoenix> In-Reply-To: <1743577152-119846-1-git-send-email-liwencheng@phytium.com.cn> References: <1743577152-119846-1-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 Wed, 2 Apr 2025 06:59:12 +0000 liwencheng wrote: > +static inline uint8x8_t macb_mbuf_initializer(struct macb_rx_queue *rxq) > +{ > + volatile struct rte_mbuf mbuf = {.buf_addr = 0}; /* zeroed mbuf */ There is no way an on stack variable could be volatile. What it looks like your are doing is trying to workaround misunderstanding of atomic. > + uint64x1_t mbuf_initializer; > + uint8x8_t rearm_data_vec; > + > + mbuf.data_off = RTE_PKTMBUF_HEADROOM + MACB_RX_DATA_OFFSET; > + mbuf.nb_segs = 1; > + mbuf.port = rxq->port_id; Why not just put these into the initializer? > + rte_mbuf_refcnt_set((struct rte_mbuf *)&mbuf, 1); > + > + /* prevent compiler reordering: rearm_data covers previous fields */ > + rte_compiler_barrier(); You would be better off doing an atomic store with the right type of memory order, rather than weak + barrier. But would have to handle case where refcounts are compiled out. > + mbuf_initializer = > + vset_lane_u64(*(uint64_t *)(&mbuf.rearm_data), mbuf_initializer, 0); Take the volatile of mbuf and you won't have compiler warning. > + rearm_data_vec = vld1_u8((uint8_t *)&mbuf_initializer); > + return rearm_data_vec; > +}