From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E3BD21A457; Sat, 7 Feb 2026 00:35:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770424521; cv=none; b=dA3urr2B98F4mBDGO6/BF2e4LLMA8jA/TidQVo/xBnDLs5RsAv7KoLRIH0irx8cNSVvLAwkVR/D+re+mE+sfDxJmDNRQFrNk0QL//wdI+U2PCK8Dec8Z2PDt8eO0FdHUHE+nv802/at41soP5abWnCgBKEuK/n8I57L9lg2+Kks= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770424521; c=relaxed/simple; bh=ebNhDFuwOCgh31SMzIMBvy0cHokX8Sm6bFlQoyAQI8w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=d2Txs3xNjC1e2HHLVuZHJux+VRFvlxWuDzG1RzyF62VuNKfkThw4LUv6MKfDGlOv4W9X9E/lHccnj+wim9LxQgGyf4D8YRoOxZFmQ+qqLq7Vnn74bmBBlG1CjQB6wUDazFzDjJWojdZuB4K3jsCDE/9KkunAL1da0SvpH58AyF4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JgwCVovX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JgwCVovX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11D0BC16AAE; Sat, 7 Feb 2026 00:35:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770424520; bh=ebNhDFuwOCgh31SMzIMBvy0cHokX8Sm6bFlQoyAQI8w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JgwCVovXmQofe3858fELa1NkaG+5/PvL/GbyKcFP7B8517aYNYXmGL3GJco6QInqP OdUJQW2EzdcKqjp0Pec3Una++UX2L0ixHPZf8gUhhzUpmcg+buYHa4oHzOci2ThjEN KdGq4dQ/TC+OQsAsrkZpkcKavHfzUUGAD2ns8al9ebGYAHJQ8OJxjjqcS7M3T6Ut/q q+jtyMkD0A3nAJ+vSP1L+hu7tb68x8t72/IkT5FjD3cFdMhLLLfJ3NwNJ//Sji6Dir +TIt8MVA5b/qX964B64VFE++ZUodN0g28Rv10C5VST1tAtR1Gi+SnPVUwCV4RvfN67 ZBcTnifYG65ug== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, shuah@kernel.org, willemb@google.com, petrm@nvidia.com, donald.hunter@gmail.com, michael.chan@broadcom.com, pavan.chebbi@broadcom.com, linux-kselftest@vger.kernel.org, Jakub Kicinski Subject: [PATCH net-next v2 6/9] selftests: drv-net: gro: use SO_TXTIME to schedule packets together Date: Fri, 6 Feb 2026 16:35:06 -0800 Message-ID: <20260207003509.3927744-7-kuba@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260207003509.3927744-1-kuba@kernel.org> References: <20260207003509.3927744-1-kuba@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Longer packet sequence tests are quite flaky when the test is run over a real network. Try to avoid at least the jitter on the sender side by scheduling all the packets to be sent at once using SO_TXTIME. Use hardcoded tx time of 5msec in the future. In my test increasing this time past 2msec makes no difference so 5msec is plenty of margin. Since we now expect more output buffering make sure to raise SNDBUF. Experimenting with long sequences I see frequent failures when sending 200 packets, only 50-100 packets get coalesced. With this change up to 1000 packets get coalesced relatively reliably. Reviewed-by: Petr Machata Signed-off-by: Jakub Kicinski --- v2: - only enable TXTIME when we are sending a single flow v1: https://lore.kernel.org/20260205220541.2992807-7-kuba@kernel.org --- tools/testing/selftests/net/lib/gro.c | 57 +++++++++++++++++++++++++-- 1 file changed, 54 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/net/lib/gro.c b/tools/testing/selftests/net/lib/gro.c index 02e29509fbea..5b3f8fca08e6 100644 --- a/tools/testing/selftests/net/lib/gro.c +++ b/tools/testing/selftests/net/lib/gro.c @@ -63,6 +63,7 @@ #include #include #include +#include #include #include #include @@ -74,6 +75,7 @@ #include #include #include +#include #include #include "kselftest.h" @@ -123,6 +125,9 @@ static int tcp_offset = -1; static int total_hdr_len = -1; static int ethhdr_proto = -1; static bool ipip; +static uint64_t txtime_ns; + +#define TXTIME_DELAY_MS 5 static void vlog(const char *fmt, ...) { @@ -330,13 +335,37 @@ static void fill_transportlayer(void *buf, int seq_offset, int ack_offset, static void write_packet(int fd, char *buf, int len, struct sockaddr_ll *daddr) { + char control[CMSG_SPACE(sizeof(uint64_t))]; + struct msghdr msg = {}; + struct iovec iov = {}; + struct cmsghdr *cm; int ret = -1; - ret = sendto(fd, buf, len, 0, (struct sockaddr *)daddr, sizeof(*daddr)); + iov.iov_base = buf; + iov.iov_len = len; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_name = daddr; + msg.msg_namelen = sizeof(*daddr); + + if (txtime_ns) { + memset(control, 0, sizeof(control)); + msg.msg_control = control; + msg.msg_controllen = sizeof(control); + + cm = CMSG_FIRSTHDR(&msg); + cm->cmsg_level = SOL_SOCKET; + cm->cmsg_type = SCM_TXTIME; + cm->cmsg_len = CMSG_LEN(sizeof(uint64_t)); + memcpy(CMSG_DATA(cm), &txtime_ns, sizeof(txtime_ns)); + } + + ret = sendmsg(fd, &msg, 0); if (ret == -1) - error(1, errno, "sendto failure"); + error(1, errno, "sendmsg failure"); if (ret != len) - error(1, errno, "sendto wrong length"); + error(1, 0, "sendmsg wrong length: %d vs %d", ret, len); } static void create_packet(void *buf, int seq_offset, int ack_offset, @@ -1058,6 +1087,7 @@ static void check_recv_pkts(int fd, int *correct_payload, static void gro_sender(void) { + int bufsize = 4 * 1024 * 1024; /* 4 MB */ const int fin_delay_us = 100 * 1000; static char fin_pkt[MAX_HDR_LEN]; struct sockaddr_ll daddr = {}; @@ -1067,6 +1097,27 @@ static void gro_sender(void) if (txfd < 0) error(1, errno, "socket creation"); + if (setsockopt(txfd, SOL_SOCKET, SO_SNDBUF, &bufsize, sizeof(bufsize))) + error(1, errno, "cannot set sndbuf size, setsockopt failed"); + + /* Enable SO_TXTIME unless test case generates more than one flow + * SO_TXTIME could result in qdisc layer sorting the packets at sender. + */ + if (true) { + struct sock_txtime so_txtime = { .clockid = CLOCK_MONOTONIC, }; + struct timespec ts; + + if (setsockopt(txfd, SOL_SOCKET, SO_TXTIME, + &so_txtime, sizeof(so_txtime))) + error(1, errno, "setsockopt SO_TXTIME"); + + if (clock_gettime(CLOCK_MONOTONIC, &ts)) + error(1, errno, "clock_gettime"); + + txtime_ns = ts.tv_sec * 1000000000ULL + ts.tv_nsec; + txtime_ns += TXTIME_DELAY_MS * 1000000ULL; + } + memset(&daddr, 0, sizeof(daddr)); daddr.sll_ifindex = if_nametoindex(ifname); if (daddr.sll_ifindex == 0) -- 2.53.0