Main differences between Linux kernel and regular C project (from developer’s point of view) are next: kernel is very big project (so you should choose which code to index) it has architecture dependent code (and you are only interested in one specific architecture at a time; other architectures shouldn’t be indexed) it has very specific … Read more
I’m actually working on exactly the same thing right now and I’m going the ioctl() route. The general idea is for user space to allocate the buffer which will be used for the DMA transfer and an ioctl() will be used to pass the size and address of this buffer to the device driver. The … Read more
This is prefaced by the top comments. The documentation you’re reading is generic [not linux specific] and a bit outdated. And, more to the point, it is using different terminology. That is, I believe, the source of the confusion. So, read on … What it calls a “user-level” thread is what I’m calling an [outdated] … Read more
A kernel thread is a task_struct with no userspace components. Besides the lack of userspace, it has different ancestors (kthreadd kernel thread instead of the init process) and is created by a kernel-only API instead of sequences of clone from fork/exec system calls. Two kernel threads have kthreadd as a parent. Apart from that, kernel … Read more
Inotify itself is a kernel module accesible via calls from e.g. a C program. https://linux.die.net/man/7/inotify There is an application suite called inotify-tools, which contains: inotifywait – wait for changes to files using inotify http://linux.die.net/man/1/inotifywait and inotifywatch – gather filesystem access statistics using inotify http://linux.die.net/man/1/inotifywatch You can use inotify directly from command line, e.g. like this … Read more
The first thing I want to point out is that you might want to double-check which cores are on each node. I don’t recall cores and nodes being interleaved like that. Also, you should have 16 threads due to HT. (unless you disabled it) Another thing: The socket 1366 Xeon machines are only slightly NUMA. … Read more
Prior to Linux kernel version 2.5.4, Linux Kernel was not preemptive which means a process running in kernel mode cannot be moved out of processor until it itself leaves the processor or it starts waiting for some input output operation to get complete. Generally a process in user mode can enter into kernel mode using … Read more
Certainly in ethtool you can just print the address: -P –show-permaddr Queries the specified network device for permanent hardware address. e.g. ethtool -P eth0 produces Permanent address: 94:de:80:6a:21:25
The neighbor cache in the Linux kernel isn’t as simple as one would think. I’ll try to explain some of the quirks with it. There are subtle differences between an neighbor cache entry actually falling out of the cache entirely or just being marked as stale/invalid. At some point between base_reachable_time/2 and 3*base_reachable_time/2, the entry … Read more
GCC attributes are a general mechanism to give instructions to the compiler that are outside the specification of the language itself. The common facility that the macros you list is the use of the __section__ attribute which is described as: The section attribute specifies that a function lives in a particular section. For example, the … Read more