


In the Linux environment, what operations may cause thread switching?
Linux uses a one-to-one thread model, and the difference between user thread switching and kernel thread switching is very small. At the same time, if you ignore the overhead caused by the user voluntarily giving up the execution rights (yield) of the user thread, you only need to consider the overhead of kernel thread switching. (Recommended learning: linux tutorial )
## 注意 Note that it is just to help the simplification of understanding. In fact, the user thread library does a lot of work in the scheduling and synchronization of user threads, and this cost cannot be ignored. For example, the JVM explains Thread#yield(): If the underlying OS does not support the semantics of yield, the JVM will let the user thread spin until the end of the time slice, and the thread will be passively switched to achieve a similar effect.What causes thread switching
Time slice rotationThread blockingThread actively gives up time sliceDirect overhead
Direct overhead is caused by the thread switching itself, which is inevitable and inevitable.Switching between user mode and kernel mode
Thread switching can only be completed in kernel mode. If the current user is in user mode, it will inevitably cause a conflict between user mode and kernel mode. switch. (What are the specific costs of "switching between user mode and kernel mode"???)Context switching
As mentioned earlier, thread (or process) information needs to be saved with a task_struct. When switching threads, it is necessary to cut out the task_struct of the old thread from the kernel and cut in the new thread to bring about context switching. In addition, it is also necessary to switch registers, program counters, thread stacks (including operation stacks, data stacks), etc.Thread Scheduling Algorithm
Thread scheduling algorithm needs to manage the status of threads, waiting conditions, etc. If it is scheduled according to priority, it also needs to maintain a priority queue. If thread switching is frequent, this cost cannot be underestimated.Indirect overhead
Indirect overhead is a side effect of direct overhead and depends on system implementation and user code implementation.Cache Missing
Switching process requires the execution of new logic. If the address spaces accessed by the two are not similar, cache misses will occur. The specific impact depends on the system implementation and user code implementation. If the system's cache is larger, the impact of cache misses can be reduced; if the address spaces where user threads access data are close to each other, the cache miss rate itself will also be relatively low.The above is the detailed content of In the Linux environment, what operations may cause thread switching?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

To enable PHP containers to support automatic construction, the core lies in configuring the continuous integration (CI) process. 1. Use Dockerfile to define the PHP environment, including basic image, extension installation, dependency management and permission settings; 2. Configure CI/CD tools such as GitLabCI, and define the build, test and deployment stages through the .gitlab-ci.yml file to achieve automatic construction, testing and deployment; 3. Integrate test frameworks such as PHPUnit to ensure that tests are automatically run after code changes; 4. Use automated deployment strategies such as Kubernetes to define deployment configuration through the deployment.yaml file; 5. Optimize Dockerfile and adopt multi-stage construction

Building an independent PHP task container environment can be implemented through Docker. The specific steps are as follows: 1. Install Docker and DockerCompose as the basis; 2. Create an independent directory to store Dockerfile and crontab files; 3. Write Dockerfile to define the PHPCLI environment and install cron and necessary extensions; 4. Write a crontab file to define timing tasks; 5. Write a docker-compose.yml mount script directory and configure environment variables; 6. Start the container and verify the log. Compared with performing timing tasks in web containers, independent containers have the advantages of resource isolation, pure environment, strong stability, and easy expansion. To ensure logging and error capture

Windowsisbetterforbeginnersduetoeaseofuse,seamlesshardwarecompatibility,andsupportformainstreamsoftwarelikeMicrosoftOfficeandAdobeapps.2.LinuxoutperformsWindowsonolderorlow-resourcehardwarewithfasterboottimes,lowersystemrequirements,andlessbloat.3.Li

Confirm the target hard disk device name (such as /dev/sda) to avoid accidentally deleting the system disk; 2. Use sudoddif=/dev/zeroof=/dev/sdXbs=1Mstatus=progress to overwrite the zero value in full disk, which is suitable for most scenarios; 3. Use sudoshred-v-n3/dev/sdX for three random data overwrites to ensure that it cannot be restored; 4. Optionally execute sudobadblocks-wsv/dev/sdX for destructive write tests; finally use sudohexdump-C/dev/sdX|head to verify whether it is all zero and complete safe erasing.

cronisusedforpreciseschedulingonalways-onsystems,whileanacronensuresperiodictasksrunonsystemsthataren'tcontinuouslypowered,suchaslaptops;1.Usecronforexacttiming(e.g.,3AMdaily)viacrontab-ewithsyntaxMINHOURDOMMONDOWCOMMAND;2.Useanacronfordaily,weekly,o

There are three main ways to install software on Linux: 1. Use a package manager, such as apt, dnf or pacman, and then execute the install command after updating the source, such as sudoaptininstallcurl; 2. For .deb or .rpm files, use dpkg or rpm commands to install, and repair dependencies when needed; 3. Use snap or flatpak to install applications across platforms, such as sudosnapinstall software name, which is suitable for users who are pursuing version updates. It is recommended to use the system's own package manager for better compatibility and performance.

ChoosePop!_OS,Ubuntu,NobaraLinux,orArchLinuxforoptimalgamingperformancewithminimaloverhead.2.InstallofficialNVIDIAproprietarydriversforNVIDIAGPUs,ensureup-to-dateMesaandkernelversionsforAMDandIntelGPUs.3.EnabletheperformanceCPUgovernor,usealow-latenc

AfterinstallingLinux,thefirststepsincludeupdatingyoursystem,installingessentialsoftware,settingupbackupandsecuritymeasures,andcustomizingtheinterfacetosuityourpreferences.1)Updateyoursystemusingtheappropriatecommandforyourdistro(e.g.,sudoaptupdate&am
