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=-2.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 0D5D4C31E49 for ; Thu, 13 Jun 2019 16:35:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E411320449 for ; Thu, 13 Jun 2019 16:35:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730695AbfFMQfy (ORCPT ); Thu, 13 Jun 2019 12:35:54 -0400 Received: from mga01.intel.com ([192.55.52.88]:5947 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730699AbfFMHhk (ORCPT ); Thu, 13 Jun 2019 03:37:40 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Jun 2019 00:37:39 -0700 X-ExtLoop1: 1 Received: from mkarlsso-mobl.ger.corp.intel.com (HELO VM.ger.corp.intel.com) ([10.103.211.41]) by orsmga004.jf.intel.com with ESMTP; 13 Jun 2019 00:37:34 -0700 From: Magnus Karlsson To: magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, brouer@redhat.com Cc: bpf@vger.kernel.org, bruce.richardson@intel.com, ciara.loftus@intel.com, jakub.kicinski@netronome.com, xiaolong.ye@intel.com, qi.z.zhang@intel.com, maximmi@mellanox.com, sridhar.samudrala@intel.com, kevin.laatz@intel.com, ilias.apalodimas@linaro.org, kiran.patil@intel.com, axboe@kernel.dk, maciej.fijalkowski@intel.com, maciejromanfijalkowski@gmail.com, intel-wired-lan@lists.osuosl.org Subject: [PATCH bpf-next 0/6] add need_wakeup flag to the AF_XDP rings Date: Thu, 13 Jun 2019 09:37:24 +0200 Message-Id: <1560411450-29121-1-git-send-email-magnus.karlsson@intel.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org This patch set adds support for a new flag called need_wakeup in the AF_XDP Tx and fill rings. When this flag is set by the driver, it means that the application has to explicitly wake up the kernel Rx (for the bit in the fill ring) or kernel Tx (for bit in the Tx ring) processing by issuing a syscall. Poll() can wake up both and sendto() will wake up Tx processing only. The main reason for introducing this new flag is to be able to efficiently support the case when application and driver is executing on the same core. Previously, the driver was just busy-spinning on the fill ring if it ran out of buffers in the HW and there were none to get from the fill ring. This approach works when the application and driver is running on different cores as the application can replenish the fill ring while the driver is busy-spinning. Though, this is a lousy approach if both of them are running on the same core as the probability of the fill ring getting more entries when the driver is busy-spinning is zero. With this new feature the driver now sets the need_wakeup flag and returns to the application. The application can then replenish the fill queue and then explicitly wake up the Rx processing in the kernel using the syscall poll(). For Tx, the flag is only set to one if the driver has no outstanding Tx completion interrupts. If it has some, the flag is zero as it will be woken up by a completion interrupt anyway. This flag can also be used in other situations where the driver needs to be woken up explicitly. As a nice side effect, this new flag also improves the Tx performance of the case where application and driver are running on two different cores as it reduces the number of syscalls to the kernel. The kernel tells user space if it needs to be woken up by a syscall, and this eliminates many of the syscalls. The Rx performance of the 2-core case is on the other hand slightly worse, since there is a need to use a syscall now to wake up the driver, instead of the driver busy-spinning. It does waste less CPU cycles though, which might lead to better overall system performance. This new flag needs some simple driver support. If the driver does not support it, the Rx flag is always zero and the Tx flag is always one. This makes any application relying on this feature default to the old behavior of not requiring any syscalls in the Rx path and always having to call sendto() in the Tx path. For backwards compatibility reasons, this feature has to be explicitly turned on using a new bind flag (XDP_USE_NEED_WAKEUP). I recommend that you always turn it on as it has a large positive performance impact for the one core case and does not degrade 2 core performance and actually improves it for Tx heavy workloads. Here are some performance numbers measured on my local, non-performance optimized development system. That is why you are seeing numbers lower than the ones from Björn and Jesper. 64 byte packets at 40Gbit/s line rate. All results in Mpps. Cores == 1 means that both application and driver is executing on the same core. Cores == 2 that they are on different cores. Applications need_wakeup cores txpush rxdrop l2fwd --------------------------------------------------------------- n 1 0.07 0.06 0.03 y 1 21.6 8.2 6.5 n 2 32.3 11.7 8.7 y 2 33.1 11.7 8.7 Overall, the need_wakeup flag provides the same or better performance in all the micro-benchmarks. The reduction of sendto() calls in txpush is large. Only a few per second is needed. For l2fwd, the drop is 50% for the 1 core case and more than 99.9% for the 2 core case. Do not know why I am not seeing the same drop for the 1 core case yet. The name and inspiration of the flag has been taken from io_uring by Jens Axboe. Details about this feature in io_uring can be found in http://kernel.dk/io_uring.pdf, section 8.3. It also addresses most of the denial of service and sendto() concerns raised by Maxim Mikityanskiy in https://www.spinics.net/lists/netdev/msg554657.html. The typical Tx part of an application will have to change from: ret = sendto(fd,....) to: if (xsk_ring_prod__needs_wakeup(&xsk->tx)) ret = sendto(fd,....) and th Rx part from: rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx); if (!rcvd) return; to: rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx); if (!rcvd) { if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq)) ret = poll(fd,.....); return; } This patch has been applied against commit aee450cbe482 ("bpf: silence warning messages in core") Structure of the patch set: Patch 1: Replaces the ndo_xsk_async_xmit with ndo_xsk_wakeup to support waking up both Rx and Tx processing Patch 2: Implements the need_wakeup functionality in common code Patch 3-4: Add need_wakeup support to the i40e and ixgbe drivers Patch 5: Add need_wakeup support to libbpf Patch 6: Add need_wakeup support to the xdpsock sample application Thanks: Magnus Magnus Karlsson (6): xsk: replace ndo_xsk_async_xmit with ndo_xsk_wakeup xsk: add support for need_wakeup flag in AF_XDP rings i40e: add support for AF_XDP need_wakup feature ixgbe: add support for AF_XDP need_wakup feature libbpf: add support for need_wakeup flag in AF_XDP part samples/bpf: add use of need_sleep flag in xdpsock drivers/net/ethernet/intel/i40e/i40e_main.c | 5 +- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 23 ++- drivers/net/ethernet/intel/i40e/i40e_xsk.h | 2 +- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 5 +- .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 2 +- drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 20 ++- include/linux/netdevice.h | 18 +- include/net/xdp_sock.h | 33 +++- include/uapi/linux/if_xdp.h | 13 ++ net/xdp/xdp_umem.c | 6 +- net/xdp/xsk.c | 93 +++++++++- net/xdp/xsk_queue.h | 1 + samples/bpf/xdpsock_user.c | 191 +++++++++++++-------- tools/include/uapi/linux/if_xdp.h | 13 ++ tools/lib/bpf/xsk.c | 4 + tools/lib/bpf/xsk.h | 6 + 16 files changed, 343 insertions(+), 92 deletions(-) -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Magnus Karlsson Date: Thu, 13 Jun 2019 09:37:24 +0200 Subject: [Intel-wired-lan] [PATCH bpf-next 0/6] add need_wakeup flag to the AF_XDP rings Message-ID: <1560411450-29121-1-git-send-email-magnus.karlsson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: This patch set adds support for a new flag called need_wakeup in the AF_XDP Tx and fill rings. When this flag is set by the driver, it means that the application has to explicitly wake up the kernel Rx (for the bit in the fill ring) or kernel Tx (for bit in the Tx ring) processing by issuing a syscall. Poll() can wake up both and sendto() will wake up Tx processing only. The main reason for introducing this new flag is to be able to efficiently support the case when application and driver is executing on the same core. Previously, the driver was just busy-spinning on the fill ring if it ran out of buffers in the HW and there were none to get from the fill ring. This approach works when the application and driver is running on different cores as the application can replenish the fill ring while the driver is busy-spinning. Though, this is a lousy approach if both of them are running on the same core as the probability of the fill ring getting more entries when the driver is busy-spinning is zero. With this new feature the driver now sets the need_wakeup flag and returns to the application. The application can then replenish the fill queue and then explicitly wake up the Rx processing in the kernel using the syscall poll(). For Tx, the flag is only set to one if the driver has no outstanding Tx completion interrupts. If it has some, the flag is zero as it will be woken up by a completion interrupt anyway. This flag can also be used in other situations where the driver needs to be woken up explicitly. As a nice side effect, this new flag also improves the Tx performance of the case where application and driver are running on two different cores as it reduces the number of syscalls to the kernel. The kernel tells user space if it needs to be woken up by a syscall, and this eliminates many of the syscalls. The Rx performance of the 2-core case is on the other hand slightly worse, since there is a need to use a syscall now to wake up the driver, instead of the driver busy-spinning. It does waste less CPU cycles though, which might lead to better overall system performance. This new flag needs some simple driver support. If the driver does not support it, the Rx flag is always zero and the Tx flag is always one. This makes any application relying on this feature default to the old behavior of not requiring any syscalls in the Rx path and always having to call sendto() in the Tx path. For backwards compatibility reasons, this feature has to be explicitly turned on using a new bind flag (XDP_USE_NEED_WAKEUP). I recommend that you always turn it on as it has a large positive performance impact for the one core case and does not degrade 2 core performance and actually improves it for Tx heavy workloads. Here are some performance numbers measured on my local, non-performance optimized development system. That is why you are seeing numbers lower than the ones from Bj?rn and Jesper. 64 byte packets at 40Gbit/s line rate. All results in Mpps. Cores == 1 means that both application and driver is executing on the same core. Cores == 2 that they are on different cores. Applications need_wakeup cores txpush rxdrop l2fwd --------------------------------------------------------------- n 1 0.07 0.06 0.03 y 1 21.6 8.2 6.5 n 2 32.3 11.7 8.7 y 2 33.1 11.7 8.7 Overall, the need_wakeup flag provides the same or better performance in all the micro-benchmarks. The reduction of sendto() calls in txpush is large. Only a few per second is needed. For l2fwd, the drop is 50% for the 1 core case and more than 99.9% for the 2 core case. Do not know why I am not seeing the same drop for the 1 core case yet. The name and inspiration of the flag has been taken from io_uring by Jens Axboe. Details about this feature in io_uring can be found in http://kernel.dk/io_uring.pdf, section 8.3. It also addresses most of the denial of service and sendto() concerns raised by Maxim Mikityanskiy in https://www.spinics.net/lists/netdev/msg554657.html. The typical Tx part of an application will have to change from: ret = sendto(fd,....) to: if (xsk_ring_prod__needs_wakeup(&xsk->tx)) ret = sendto(fd,....) and th Rx part from: rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx); if (!rcvd) return; to: rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx); if (!rcvd) { if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq)) ret = poll(fd,.....); return; } This patch has been applied against commit aee450cbe482 ("bpf: silence warning messages in core") Structure of the patch set: Patch 1: Replaces the ndo_xsk_async_xmit with ndo_xsk_wakeup to support waking up both Rx and Tx processing Patch 2: Implements the need_wakeup functionality in common code Patch 3-4: Add need_wakeup support to the i40e and ixgbe drivers Patch 5: Add need_wakeup support to libbpf Patch 6: Add need_wakeup support to the xdpsock sample application Thanks: Magnus Magnus Karlsson (6): xsk: replace ndo_xsk_async_xmit with ndo_xsk_wakeup xsk: add support for need_wakeup flag in AF_XDP rings i40e: add support for AF_XDP need_wakup feature ixgbe: add support for AF_XDP need_wakup feature libbpf: add support for need_wakeup flag in AF_XDP part samples/bpf: add use of need_sleep flag in xdpsock drivers/net/ethernet/intel/i40e/i40e_main.c | 5 +- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 23 ++- drivers/net/ethernet/intel/i40e/i40e_xsk.h | 2 +- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 5 +- .../net/ethernet/intel/ixgbe/ixgbe_txrx_common.h | 2 +- drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 20 ++- include/linux/netdevice.h | 18 +- include/net/xdp_sock.h | 33 +++- include/uapi/linux/if_xdp.h | 13 ++ net/xdp/xdp_umem.c | 6 +- net/xdp/xsk.c | 93 +++++++++- net/xdp/xsk_queue.h | 1 + samples/bpf/xdpsock_user.c | 191 +++++++++++++-------- tools/include/uapi/linux/if_xdp.h | 13 ++ tools/lib/bpf/xsk.c | 4 + tools/lib/bpf/xsk.h | 6 + 16 files changed, 343 insertions(+), 92 deletions(-) -- 2.7.4