From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751743AbcGROXs (ORCPT ); Mon, 18 Jul 2016 10:23:48 -0400 Received: from mga14.intel.com ([192.55.52.115]:9005 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752100AbcGROXh (ORCPT ); Mon, 18 Jul 2016 10:23:37 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,384,1464678000"; d="scan'208";a="1009027711" From: kan.liang@intel.com To: davem@davemloft.net, linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org Cc: jeffrey.t.kirsher@intel.com, mingo@redhat.com, peterz@infradead.org, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, akpm@linux-foundation.org, keescook@chromium.org, viro@zeniv.linux.org.uk, gorcunov@openvz.org, john.stultz@linaro.org, aduyck@mirantis.com, ben@decadent.org.uk, decot@googlers.com, jesse.brandeburg@intel.com, andi@firstfloor.org, Kan Liang Subject: [RFC PATCH 30/30] Documentation/networking: Document net policy Date: Sun, 17 Jul 2016 23:56:24 -0700 Message-Id: <1468824984-65318-31-git-send-email-kan.liang@intel.com> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1468824984-65318-1-git-send-email-kan.liang@intel.com> References: <1468824984-65318-1-git-send-email-kan.liang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kan Liang Signed-off-by: Kan Liang --- Documentation/networking/netpolicy.txt | 158 +++++++++++++++++++++++++++++++++ 1 file changed, 158 insertions(+) create mode 100644 Documentation/networking/netpolicy.txt diff --git a/Documentation/networking/netpolicy.txt b/Documentation/networking/netpolicy.txt new file mode 100644 index 0000000..2ce938e --- /dev/null +++ b/Documentation/networking/netpolicy.txt @@ -0,0 +1,158 @@ +What is Linux Net Policy? + +It is a big challenge to get good network performance. First, the network +performance is not good with default system settings. Second, it is too +difficult to do automatic tuning for all possible workloads, since workloads +have different requirements. Some workloads may want high throughput. Some may +need low latency. Last but not least, there are lots of manual configurations. +Fine grained configuration is too difficult for users. + +"NET policy" intends to simplify the network configuration and get a +good network performance according to the hints(policy) which is applied by +user. It provides some typical "policies" for user which can be set +per-socket, per-task or per-device. The kernel will automatically figures out +how to merge different requests to get good network performance. + +"Net policy" is designed for multiqueue network devices. This document +describes the concepts and APIs of "net policy" support. + +NET POLICY CONCEPTS + +Scope of Net Policies + + Device net policy: this policy applies to the whole device. Once the + device net policy is set, it automatically configures the system + according to the applied policy. The configuration usually includes irq + affinity, irq balance disable, interrupt moderation, and so on. But the + device net policy does not change the packet direction. + + Task net policy: this is a per-task policy. When it is applied to specific + task, all packets transmissions of the task will be redirect to the + assigned queues accordingly. If a task does not define a task policy, + it "falls back" to the system default way to direct the packets. The + per-task policy must be compatible with device net policy. + + Socket net policy: this is a per-socket policy. When it is applied to + specific socket, all packets transmissions of the socket will be redirect + to the assigned queues accordingly. If a socket does not define a socket + policy, it "falls back" to the system default way to direct the packets. + The per-socket policy must be compatible with both device net policy and + per-task policy. + +Components of Net Policies + + Net policy object: it is a combination of cpu and queue. The queue irq has + to set affinity with the cpu. It can be shared between sockets and tasks. + A reference counter is used to track the sharing number. + + Net policy object list: each device policy has an object list. Once the + device policy is determined, the net policy object will be inserted into + the net policy object list. The net policy object list does not change + unless the cpu/queue number is changed, the netpolicy is disabled or + the device policy is changed. + The network performance for objects could be different because of the + queue/cpu topology and dev location. The objects which can bring high + performance are in the front of the list. + + RCU hash table: a RCU hash table to maintain the relationship between + the task/socket and the assigned object. The task/socket can get the + assigned object by searching the table. + If it is the first time, there is no assigned object in the table. It will + go through the object list to find the available object based on position + and reference number. + If the net policy object list changes, all the assigned object will become + invalid. + +NET POLICY APIs + +Interfaces between net policy and device driver + + int (*ndo_netpolicy_init)(struct net_device *dev, + struct netpolicy_info *info); + + The device driver who has NET policy support must implement this interface. + In this interface, the device driver do necessory initialization, and fill + the info for net policy module. The information could inlcude supported + policy, MIX policy support, queue pair support and so on. + + int (*ndo_get_irq_info)(struct net_device *dev, + struct netpolicy_dev_info *info); + + This interface is used to get more accurate device irq information. + + int (*ndo_set_net_policy)(struct net_device *dev, + enum netpolicy_name name); + + This interface is used to set device net policy by name + +Interfaces between net policy and kernel + + int netpolicy_register(struct netpolicy_reg *reg); + void netpolicy_unregister(struct netpolicy_reg *reg); + + This interface is used to register per task/socket net policy. + If it's the first time to register, an record will be created and inserted + into RCU hash table. The record includes ptr, policy and object + information. There is only one user for each record. The record cannot be + share. + + + int netpolicy_pick_queue(struct netpolicy_reg *reg, bool is_rx); + + This interface is used to find the proper queue(object) for packet + receiving and transmitting. The proper queue is picked from object list + according to policy, reference, location and so on. + + + int netpolicy_set_rules(struct netpolicy_reg *reg, + u32 queue_index, + struct netpolicy_flow_spec *flow); + + This interface is used to add device specific rules. Once the rule is + applied, the packet from specific IP and port will be redirect to the + given queue. This interface usually be used in receive side. + +NET POLICY INTERFACE + +Device net policy setting + + /proc/net/netpolicy/$DEV/policy + + Concatenating(cat) the "policy" file can show the available device + policies, if there is no device policy applied. Otherwise, the device + policy name will be print out. If it is MIX policy, the policy for each + queue will also be print out. + User can set device net policy by writing policy name. + +Task policy setting + + /proc/$PID/net_policy + + Concatenating(cat) the "net_policy" file can show the applied per task + policy. + User can set per task net policy by writing policy name. + + OR + + prctl(PR_SET_NETPOLICY, POLICY_NAME, NULL, NULL, NULL) + + "prctl" is an alternative way to set/get per task policy. + +Socket policy setting + + setsockopt(sockfd,SOL_SOCKET,SO_NETPOLICY,&policy,sizeof(int)) + + The socket net policy can be set by option SO_NETPOLICY of setsockopt + +AVAILABLE NET POLICIES + + The available net policies are defined as below: + - CPU: intends to get higher throughput and lower CPU%. This policy can be + applied as either device net policy or task/socket net policy. + - BULK: intends to get highest throughput. This policy can be applied as + either device net policy or task/socket net policy. + - LATENCY: intends to get lowest latency. This policy can be applied as + either device net policy or task/socket net policy. + - MIX: combination of other policies, which allows each queue has + different policy. This policy can only be set as device net policy. + -- 2.5.5