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 Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by smtp.lore.kernel.org (Postfix) with ESMTP id C161ED35697 for ; Wed, 28 Jan 2026 09:36:35 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 0C17F40613; Wed, 28 Jan 2026 10:36:23 +0100 (CET) Received: from mail-dy1-f175.google.com (mail-dy1-f175.google.com [74.125.82.175]) by mails.dpdk.org (Postfix) with ESMTP id D9606402DB for ; Wed, 28 Jan 2026 10:36:19 +0100 (CET) Received: by mail-dy1-f175.google.com with SMTP id 5a478bee46e88-2b729f4c154so11568403eec.0 for ; Wed, 28 Jan 2026 01:36:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769592979; x=1770197779; darn=dpdk.org; 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=YQD+UZnE/x+JI78VtpePZq9iPel0TiL+1/Swo8B8MJw=; b=fynk+2Ls0fdxtQ1FjkwGqFMyf4hbqhP2gOAxDB+Z2nHJdOs6aNMo2Es4Y+RjyxG0c2 EGD6D72S2uwnO3k3+nB8+18/1hbbbWCn86qNY5qVlLPCEgJRsLVfw/7z58Al4UiOpw+H uXUpO5Jj41kTfZUrAggNY7aKcHvHH+sXz5OaIBRMmr3HYUIK2Px0APs7Ms+JoNF+gIFM FwNWykHLZzkHYI16Szg9AgkNtw+P4B0J9120RAeloBMqqDZN1DlSNVWwCFK0Eo4JMAi9 3+/evRkncKpF556O0LSE5c2D6UbtyWfCoEtTbG4A3nUUqCJq+wqut1CepBz7iFo6S4CN UyFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769592979; x=1770197779; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=YQD+UZnE/x+JI78VtpePZq9iPel0TiL+1/Swo8B8MJw=; b=nN08G2P8U59ExwweE73KGqD6xB18xunezDyct4Ifmca+ZKhcXf+qW0UyExrBwdp2T8 /UGk4LpuwG12+hRhEbuiVfGJPu6ciDt+5TlaG2+Jd8oH2qiIfIxsYNvDuP2fp2PNJJXy 5VIABMZNMhfNKjl/fcN3gQeVrGVlStckv72zWir4IpJjaq5qNswlP5c1Mh+OXOED1uJU bvBzbeRYJ/evACbTnbRM83mECZZdZEeX5ftfxUiVbYGZ6qQCLeEP2K8xWZfoA/D7BfhP Vh9d8/1WriURGzbqsVFp+U3cI2xgwXAnRk2pvqlf8yCnX1Bpv0v9PXeh/AmoslVXxmwq mWOQ== X-Gm-Message-State: AOJu0Yzyh3aLMbdcXlCL5/d/fNSCV0oLzSkWq7aguWtQ0IeBpeaNh0I4 CDQ2ZjYJ2GqRqJOtzjqKxfHhFCDPkX+f9h2EorqzR3QVrpvy5hamDx5fsazzJw== X-Gm-Gg: AZuq6aIH35i6s0kt2+3EKoOlXnJr0O38+oS1xfmmMkIwFtS8Vtoj5rjqzoZmVOsOkVJ t44mHvzRiMfvugI+yZzXxh5hQp7EM/TqU2NZT5MU5P7A5cOslcZRyi3nSEUwgKEtxLCAdT24AbY Qzn+CZ/ZF63JjHFipoX52H3a4SsSQ1RdefQlOV6A93P09Zlo9fYEGaZOCGX8W4HtqZABkynEV5j bJBip0NAgqV3IF5oMxz/EoD99LtBZhG+dXRgvheVhOM29grj+TVy6iJR/jglLIdTwMuZoQed46a tExMxgJLvWaPT83PPZ0OuWF8anHe4SBnfppAVIumASxbMvFcXPheDff5z7PFMeRhltmLKAWlxji Lh0qflVI0KaIkQ4+98Lx/WvjUJ0ryto9daSbL7NtK6Zz9eT+iolWS9HYYebPovhOTaiaNKW0pD7 utBE66r2R0lhpGOkBDo9ztfo96LJ+4uBam X-Received: by 2002:a05:7300:6ca1:b0:2b7:1d54:87e5 with SMTP id 5a478bee46e88-2b78d90c1camr2930532eec.13.1769592978613; Wed, 28 Jan 2026 01:36:18 -0800 (PST) Received: from mac.com ([136.24.82.250]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b7a14bb02csm1834864eec.0.2026.01.28.01.36.18 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 28 Jan 2026 01:36:18 -0800 (PST) From: scott.k.mitch1@gmail.com To: dev@dpdk.org Cc: stephen@networkplumber.org, Scott Mitchell Subject: [PATCH v2 3/4] net/af_packet: tx poll control Date: Wed, 28 Jan 2026 01:36:06 -0800 Message-Id: <20260128093607.62908-4-scott.k.mitch1@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20260128093607.62908-1-scott.k.mitch1@gmail.com> References: <20260127181355.98437-1-scott.k.mitch1@gmail.com> <20260128093607.62908-1-scott.k.mitch1@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 From: Scott Mitchell Add txpollnotrdy devarg (default=true) to control whether poll() is called when the TX ring is not ready. This allows users to avoid blocking behavior if application threads are in asynchronous poll mode where blocking the thread has negative side effects and backpressure is applied via different means. Signed-off-by: Scott Mitchell --- doc/guides/nics/af_packet.rst | 6 +++- drivers/net/af_packet/rte_eth_af_packet.c | 34 ++++++++++++++++++----- 2 files changed, 32 insertions(+), 8 deletions(-) diff --git a/doc/guides/nics/af_packet.rst b/doc/guides/nics/af_packet.rst index 1505b98ff7..782a962c3f 100644 --- a/doc/guides/nics/af_packet.rst +++ b/doc/guides/nics/af_packet.rst @@ -29,6 +29,10 @@ Some of these, in turn, will be used to configure the PACKET_MMAP settings. * ``framesz`` - PACKET_MMAP frame size (optional, default 2048B; Note: multiple of 16B); * ``framecnt`` - PACKET_MMAP frame count (optional, default 512). +* ``txpollnotrdy`` - Control behavior if tx is attempted but there is no + space available to write to the kernel. If 1, call poll() and block until + space is available to tx. If 0, don't call poll() and return from tx (optional, + default 1). For details regarding ``fanout_mode`` argument, you can consult the `PACKET_FANOUT documentation `_. @@ -75,7 +79,7 @@ framecnt=512): .. code-block:: console - --vdev=eth_af_packet0,iface=tap0,blocksz=4096,framesz=2048,framecnt=512,qpairs=1,qdisc_bypass=0,fanout_mode=hash + --vdev=eth_af_packet0,iface=tap0,blocksz=4096,framesz=2048,framecnt=512,qpairs=1,qdisc_bypass=0,fanout_mode=hash,txpollnotrdy=0 Features and Limitations ------------------------ diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c index e357ae168b..be8e3260aa 100644 --- a/drivers/net/af_packet/rte_eth_af_packet.c +++ b/drivers/net/af_packet/rte_eth_af_packet.c @@ -18,6 +18,7 @@ #include #include +#include #include #include #include @@ -39,9 +40,11 @@ #define ETH_AF_PACKET_FRAMECOUNT_ARG "framecnt" #define ETH_AF_PACKET_QDISC_BYPASS_ARG "qdisc_bypass" #define ETH_AF_PACKET_FANOUT_MODE_ARG "fanout_mode" +#define ETH_AF_PACKET_TX_POLL_NOT_READY_ARG "txpollnotrdy" #define DFLT_FRAME_SIZE (1 << 11) #define DFLT_FRAME_COUNT (1 << 9) +#define DFLT_TX_POLL_NOT_RDY true static const uint16_t ETH_AF_PACKET_FRAME_SIZE_MAX = RTE_IPV4_MAX_PKT_LEN; #define ETH_AF_PACKET_FRAME_OVERHEAD (TPACKET2_HDRLEN - sizeof(struct sockaddr_ll)) @@ -78,6 +81,9 @@ struct __rte_cache_aligned pkt_tx_queue { unsigned int framecount; unsigned int framenum; + bool txpollnotrdy; + bool sw_cksum; + volatile unsigned long tx_pkts; volatile unsigned long err_pkts; volatile unsigned long tx_bytes; @@ -106,6 +112,7 @@ static const char *valid_arguments[] = { ETH_AF_PACKET_FRAMECOUNT_ARG, ETH_AF_PACKET_QDISC_BYPASS_ARG, ETH_AF_PACKET_FANOUT_MODE_ARG, + ETH_AF_PACKET_TX_POLL_NOT_READY_ARG, NULL }; @@ -265,10 +272,12 @@ eth_af_packet_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) uint32_t num_tx_bytes = 0; uint16_t i; - memset(&pfd, 0, sizeof(pfd)); - pfd.fd = pkt_q->sockfd; - pfd.events = POLLOUT; - pfd.revents = 0; + if (pkt_q->txpollnotrdy) { + memset(&pfd, 0, sizeof(pfd)); + pfd.fd = pkt_q->sockfd; + pfd.events = POLLOUT; + pfd.revents = 0; + } framecount = pkt_q->framecount; framenum = pkt_q->framenum; @@ -308,8 +317,9 @@ eth_af_packet_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) * This results in poll() returning POLLOUT. */ if (unlikely(!tx_ring_status_available(tpacket_read_status(&ppd->tp_status)) && - (poll(&pfd, 1, -1) < 0 || (pfd.revents & POLLERR) != 0 || - !tx_ring_status_available(tpacket_read_status(&ppd->tp_status))))) { + (!pkt_q->txpollnotrdy || poll(&pfd, 1, -1) < 0 || + (pfd.revents & POLLERR) != 0 || + !tx_ring_status_available(tpacket_read_status(&ppd->tp_status))))) { /* Ring is full, stop here. Don't process bufs[i]. */ break; } @@ -820,6 +830,7 @@ rte_pmd_init_internals(struct rte_vdev_device *dev, unsigned int framecnt, unsigned int qdisc_bypass, const char *fanout_mode, + bool txpollnotrdy, struct pmd_internals **internals, struct rte_eth_dev **eth_dev, struct rte_kvargs *kvlist) @@ -1038,6 +1049,7 @@ rte_pmd_init_internals(struct rte_vdev_device *dev, tx_queue->rd[i].iov_len = req->tp_frame_size; } tx_queue->sockfd = qsockfd; + tx_queue->txpollnotrdy = txpollnotrdy; rc = bind(qsockfd, (const struct sockaddr*)&sockaddr, sizeof(sockaddr)); if (rc == -1) { @@ -1126,6 +1138,7 @@ rte_eth_from_packet(struct rte_vdev_device *dev, unsigned int qpairs = 1; unsigned int qdisc_bypass = 1; const char *fanout_mode = NULL; + bool txpollnotrdy = DFLT_TX_POLL_NOT_RDY; /* do some parameter checking */ if (*sockfd < 0) @@ -1193,6 +1206,10 @@ rte_eth_from_packet(struct rte_vdev_device *dev, fanout_mode = pair->value; continue; } + if (strstr(pair->key, ETH_AF_PACKET_TX_POLL_NOT_READY_ARG) != NULL) { + txpollnotrdy = atoi(pair->value) != 0; + continue; + } } if (framesize > blocksize) { @@ -1261,12 +1278,14 @@ rte_eth_from_packet(struct rte_vdev_device *dev, PMD_LOG(DEBUG, "%s:\tfanout mode %s", name, fanout_mode); else PMD_LOG(DEBUG, "%s:\tfanout mode %s", name, "default PACKET_FANOUT_HASH"); + PMD_LOG(INFO, "%s:\ttxpollnotrdy %d", name, txpollnotrdy ? 1 : 0); if (rte_pmd_init_internals(dev, *sockfd, qpairs, blocksize, blockcount, framesize, framecount, qdisc_bypass, fanout_mode, + txpollnotrdy, &internals, ð_dev, kvlist) < 0) return -1; @@ -1364,4 +1383,5 @@ RTE_PMD_REGISTER_PARAM_STRING(net_af_packet, "framesz= " "framecnt= " "qdisc_bypass=<0|1> " - "fanout_mode="); + "fanout_mode= " + "txpollnotrdy=<0|1>"); -- 2.39.5 (Apple Git-154)