Official MongoDB documentation gives several solutions for this issue. You can also try this solution, which worked for me: Note: Try official documentation directives if MongoDB version is greater than 3.0 Open /etc/init.d/mongod file. (if no such file you might check /etc/init.d/mongod, /etc/init/mongod.conf files – credit: the below comments) Add the lines below immediately after … Read more
Because… many programs don’t use floating point or don’t use it on any given time slice; and saving the FPU registers and other FPU state takes time; therefore …an OS kernel may simply turn the FPU off. Presto, no state to save and restore, and therefore faster context-switching. (This is what mode meant, it just … Read more
The solution to the bad thread wake up performance problem in recent kernels has to do with the switch to the intel_idle cpuidle driver from acpi_idle, the driver used in older kernels. Sadly, the intel_idle driver ignores the user’s BIOS configuration for the C-states and dances to its own tune. In other words, even if … Read more
What is the difference between them? Image: the generic Linux kernel binary image file. zImage: a compressed version of the Linux kernel image that is self-extracting. uImage: an image file that has a U-Boot wrapper (installed by the mkimage utility) that includes the OS type and loader information. A very common practice (e.g. the typical … Read more
Your usage example container_of(dev, struct wifi_device, dev); might be a bit misleading as you are mixing two namespaces there. While the first dev in your example refers to the name of pointer the second dev refers to the name of a structure member. Most probably this mix up is provoking all that headache. In fact … Read more
Instead of gdb, run gdbtui. Or run gdb with the -tui switch. Or press C-x C-a after entering gdb. Now you’re in GDB’s TUI mode. Enter layout asm to make the upper window display assembly — this will automatically follow your instruction pointer, although you can also change frames or scroll around while debugging. Press … Read more
The vsyscall and vDSO segments are two mechanisms used to accelerate certain system calls in Linux. For instance, gettimeofday is usually invoked through this mechanism. The first mechanism introduced was vsyscall, which was added as a way to execute specific system calls which do not need any real level of privilege to run in order … Read more
I used to maintain CryoPID, which is a program that does exactly what you are talking about. It writes the contents of a program’s address space, VDSO, file descriptor references and states to a file that can later be reconstructed. CryoPID started when there were no usable hooks in Linux itself and worked entirely from … Read more
The four threads will have the same PID but only when viewed from above. What you (as a user) calls a PID is not what the kernel (looking from below) calls a PID. In the kernel, each thread has its own ID, called a PID, although it would possibly make more sense to call this … Read more
You should be aware that you should avoid file I/O from within Linux kernel when possible. The main idea is to go “one level deeper” and call VFS level functions instead of the syscall handler directly: Includes: #include <linux/fs.h> #include <asm/segment.h> #include <asm/uaccess.h> #include <linux/buffer_head.h> Opening a file (similar to open): struct file *file_open(const char … Read more