userkernelcommunication's Introduction

UserKernelCommunication

About the code

This repository provides test environment to test various mechanism for communications between userland and kernelland. Mechanisms were choosen regardless of how 'dirty' they are considered to be. (ex : /pipe).

The following test environments are provided:

Netlink with pre-allocated buffer of fixed size for reception and no resynchronisation (/netlink_simple)
Generic Netlink for pseudo-synchronous I/O (transactions), and asynchronous I/O (/genetlink)
A character device module with read/write callback (/rwdev)
A character device module with mmap callback (/mmapdev)
Relay API with debugfs files (/relay)
POSIX pipe IPC (/pipe)

Some mechanism provide two implementations:

An implementation for user to kernel communication;
An implementation for kernel to user communication.

Each implementation has:

a kern directory containing the module to be added to the kernel;
a user directory containing a binary to communicate with the module.

How to run the different test yourself ?

In user land, output can be read in stdout. In kernel land, output can be read with 'dmesg'.

netlink_simple:

KernToUser : First launch user/nlreader then load nlkern module.

netlink_synchro:

KernToUser : First launch user/nlreader then load nlkern module.

genetlink:

First, load genlbench module, then genlbench_test. Finally, user/benchclient will run tests.

rwdev:

mmapdev:

relay:

pipe:

Some results

Tests were run on an Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz with 2 core and 2 threads per core. Results are provided in clock cycles/messages. Messages are all 1000 to 1024 bytes long.

User to Kernel :

	User Sending	Kernel receiving
netlink_simple	15 000	NO DATA
netlink_synchro	NOT IMPLEMENTED	NOT IMPLEMENTED
rwdev	52 405	182
mmapdev
relay	NOT POSSIBLE	NOT POSSIBLE
pipe	NOT IMPLEMENTED	NOT IMPLEMENTED

Kernel to User:

	Kernel Sending	User receiving
netlink_simple	3 498	3 724
netlink_synchro	1 502	5 601
rwdev	NOT IMPLEMENTED	NOT IMPLEMENTED
mmapdev	NOT IMPLEMENTED	NOT IMPLEMENTED
relay	158	6078
pipe	4 620	4 622

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