[RFC PATCH 00/30] Kernel NET policy

From: kan . liang
Date: Mon Jul 18 2016 - 10:23:22 EST

From: Kan Liang <kan.liang@xxxxxxxxx>

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 implementation is
only for Intel NICs using i40e driver. But the concepts and generic code should
apply to other multiqueue NICs too.
Net policy is also a combination of generic policy manager code and some
ethtool callbacks (per queue coalesce setting, flow classification rules) to
configure the driver.
This series also supports CPU hotplug and device hotplug.

Here are some key Interfaces/APIs for NET policy.

User can set/get per device policy from /proc

User can set/get per task policy from /proc
An alternative way to set/get per task policy is from prctl.

User can set/get per socket policy by setsockopt

int (*ndo_netpolicy_init)(struct net_device *dev,
struct netpolicy_info *info);
Initialize device driver for NET policy

int (*ndo_get_irq_info)(struct net_device *dev,
struct netpolicy_dev_info *info);
Collect device irq information

int (*ndo_set_net_policy)(struct net_device *dev,
enum netpolicy_name name);
Configure device according to policy name

netpolicy_register(struct netpolicy_reg *reg);
netpolicy_unregister(struct netpolicy_reg *reg);
NET policy API to register/unregister per task/socket net policy.
For each task/socket, an record will be created and inserted into an RCU
hash table.

netpolicy_pick_queue(struct netpolicy_reg *reg, bool is_rx);
NET policy API to find the proper queue for packet receiving and

netpolicy_set_rules(struct netpolicy_reg *reg, u32 queue_index,
struct netpolicy_flow_spec *flow);
NET policy API to add flow director rules.

For using NET policy, the per-device policy must be set in advance. It will
automatically configure the system and re-organize the resource of the system
accordingly. For system configuration, in this series, it will disable irq
balance, set device queue irq affinity, and modify interrupt moderation. For
re-organizing the resource, current implementation forces that CPU and queue
irq are 1:1 mapping. An 1:1 mapping group is also called net policy object.
For each device policy, it maintains a policy list. Once the device policy is
applied, the objects will be insert and tracked in that device policy list. The
policy list only be updated when cpu/device hotplug, queue number changes or
device policy changes.
The user can use /proc, prctl and setsockopt to set per-task and per-socket
net policy. Once the policy is set, an related record will be inserted into RCU
hash table. The record includes ptr, policy and net policy object. The ptr is
the pointer address of task/socket. The object will not be assigned until the
first package receive/transmit. The object is picked by round-robin from object
list. Once the object is determined, the following packets will be set to
redirect to the queue(object).
The object can be shared. The per-task or per-socket policy can be inherited.

Now NET policy supports four per device policies and three per task/socket
- BULK policy: This policy is designed for high throughput. It can be
applied to either per device policy or per task/socket policy.
- CPU policy: This policy is designed for high throughput but lower CPU
utilization. It can be applied to either per device policy or
per task/socket policy.
- LATENCY policy: This policy is designed for low latency. It can be
applied to either per device policy or per task/socket policy.
- MIX policy: This policy can only be applied to per device policy. This
is designed for the case which miscellaneous types of workload running
on the device.

Lots of tests are done for net policy on platforms with Intel Xeon E5 V2
and XL710 40G NIC. The baseline test is with Linux 4.6.0 kernel.
Netperf is used to evaluate the throughput and latency performance.
- "netperf -f m -t TCP_RR -H server_IP -c -C -l 60 -- -r buffersize
-b burst -D" is used to evaluate throughput performance, which is
called throughput-first workload.
- "netperf -t TCP_RR -H server_IP -c -C -l 60 -- -r buffersize" is
used to evaluate latency performance, which is called latency-first
- Different loads are also evaluated by running 1, 12, 24, 48 or 96
throughput-first workloads/latency-first workload simultaneously.

For "BULK" policy, the throughput performance is on average ~1.26X than
For "CPU" policy, the throughput performance is on average ~1.20X than
baseline, and has lower CPU% (on average ~5% lower than "BULK" policy).
For "LATENCY" policy, the latency is on average 53.5% less than the baseline.
For "MIX" policy, mixed workloads performance is evaluated.
The mixed workloads are combination of throughput-first workload and
latency-first workload. Five different types of combinations are evaluated
(pure throughput-first workload, pure latency-first workloads,
2/3 throughput-first workload + 1/3 latency-first workloads,
1/3 throughput-first workload + 2/3 latency-first workloads and
1/2 throughput-first workload + 1/2 latency-first workloads).
For caculating the performance of mixed workloads, a weighted sum system
is introduced.
Score = normalized_latency * Weight + normalized_throughput * (1 - Weight).
If we assume that the user has an equal interest in latency and throughput
performance, the Score for "MIX" policy is on average ~1.52X than baseline.

Kan Liang (30):
net: introduce NET policy
net/netpolicy: init NET policy
i40e/netpolicy: Implement ndo_netpolicy_init
net/netpolicy: get driver information
i40e/netpolicy: implement ndo_get_irq_info
net/netpolicy: get CPU information
net/netpolicy: create CPU and queue mapping
net/netpolicy: set and remove irq affinity
net/netpolicy: enable and disable net policy
net/netpolicy: introduce netpolicy object
net/netpolicy: set net policy by policy name
i40e/netpolicy: implement ndo_set_net_policy
i40e/netpolicy: add three new net policies
net/netpolicy: add MIX policy
i40e/netpolicy: add MIX policy support
net/netpolicy: net device hotplug
net/netpolicy: support CPU hotplug
net/netpolicy: handle channel changes
net/netpolicy: implement netpolicy register
net/netpolicy: introduce per socket netpolicy
net/policy: introduce netpolicy_pick_queue
net/netpolicy: set tx queues according to policy
i40e/ethtool: support RX_CLS_LOC_ANY
net/netpolicy: set rx queues according to policy
net/netpolicy: introduce per task net policy
net/netpolicy: set per task policy by proc
net/netpolicy: fast path for finding the queues
net/netpolicy: optimize for queue pair
net/netpolicy: limit the total record number
Documentation/networking: Document net policy

Documentation/networking/netpolicy.txt | 158 +++
arch/alpha/include/uapi/asm/socket.h | 2 +
arch/avr32/include/uapi/asm/socket.h | 2 +
arch/frv/include/uapi/asm/socket.h | 2 +
arch/ia64/include/uapi/asm/socket.h | 2 +
arch/m32r/include/uapi/asm/socket.h | 2 +
arch/mips/include/uapi/asm/socket.h | 2 +
arch/mn10300/include/uapi/asm/socket.h | 2 +
arch/parisc/include/uapi/asm/socket.h | 2 +
arch/powerpc/include/uapi/asm/socket.h | 2 +
arch/s390/include/uapi/asm/socket.h | 2 +
arch/sparc/include/uapi/asm/socket.h | 2 +
arch/xtensa/include/uapi/asm/socket.h | 2 +
drivers/net/ethernet/intel/i40e/i40e.h | 3 +
drivers/net/ethernet/intel/i40e/i40e_ethtool.c | 44 +-
drivers/net/ethernet/intel/i40e/i40e_main.c | 174 +++
fs/proc/base.c | 64 ++
include/linux/init_task.h | 14 +
include/linux/netdevice.h | 31 +
include/linux/netpolicy.h | 160 +++
include/linux/sched.h | 5 +
include/net/net_namespace.h | 3 +
include/net/request_sock.h | 4 +-
include/net/sock.h | 10 +
include/uapi/asm-generic/socket.h | 2 +
include/uapi/linux/prctl.h | 4 +
kernel/exit.c | 4 +
kernel/fork.c | 11 +
kernel/sys.c | 31 +
net/Kconfig | 7 +
net/core/Makefile | 1 +
net/core/dev.c | 30 +-
net/core/ethtool.c | 8 +-
net/core/netpolicy.c | 1387 ++++++++++++++++++++++++
net/core/sock.c | 46 +
net/ipv4/af_inet.c | 75 ++
net/ipv4/udp.c | 4 +
37 files changed, 2294 insertions(+), 10 deletions(-)
create mode 100644 Documentation/networking/netpolicy.txt
create mode 100644 include/linux/netpolicy.h
create mode 100644 net/core/netpolicy.c