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Linux kernel

348 articles · Page 4 of 4
OPPO Kernel Craftsman
OPPO Kernel Craftsman
Apr 24, 2020 · Fundamentals

Evolution from Radix Tree to XArray in the Linux Kernel

The Linux kernel’s page‑cache indexing migrated from the classic radix‑tree structure—using shift‑based multi‑way nodes, RCU‑protected insert, lookup, and delete operations—to the newer XArray API introduced in 4.20, which retains the radix layout while offering automatic resizing, built‑in locking, richer marking, and a cleaner, safer interface.

Data StructuresLinux kernelRCU
0 likes · 17 min read
Evolution from Radix Tree to XArray in the Linux Kernel
OPPO Kernel Craftsman
OPPO Kernel Craftsman
Apr 17, 2020 · Fundamentals

Linux Kernel devfreq Framework: Architecture, Interfaces, and Workflow

Linux’s devfreq framework provides a generic DVFS subsystem for non‑CPU devices, defining standardized kernel‑space structures (devfreq_profile, devfreq_governor, devfreq_device) and sysfs user‑space interfaces, and managing device initialization, frequency scaling via governors, and clean removal, enabling flexible power‑performance optimization across heterogeneous SoC components.

Linux kernelOPPdevfreq
0 likes · 10 min read
Linux Kernel devfreq Framework: Architecture, Interfaces, and Workflow
UCloud Tech
UCloud Tech
Apr 2, 2020 · Operations

How Flowtable Hardware Offload Boosted Linux Netfilter Performance by Up to 8×

This article details the development, testing, and patch contributions for Netfilter and Mellanox flowtable hardware offload, showing how offloading conntrack and NAT functions dramatically improves bandwidth and packet‑per‑second metrics while exposing remaining challenges such as neighbor handling and port mangling.

Linux kernelNATNetwork Performance
0 likes · 15 min read
How Flowtable Hardware Offload Boosted Linux Netfilter Performance by Up to 8×
Xiaokun's Architecture Exploration Notes
Xiaokun's Architecture Exploration Notes
Mar 18, 2020 · Backend Development

Mastering epoll: Deep Dive into Linux I/O Multiplexing

This article thoroughly examines Linux's epoll mechanism, detailing its SLAB memory management, middle‑layer design, edge and level triggering, comparison with select/poll, and related advanced polling technologies such as /dev/poll and kqueue, while also discussing C10K/C10M challenges and practical solutions.

C10KI/O multiplexingLinux kernel
0 likes · 19 min read
Mastering epoll: Deep Dive into Linux I/O Multiplexing
Meituan Technology Team
Meituan Technology Team
Mar 12, 2020 · Information Security

Cloud Native Security: Container Escape and Mitigation Strategies

Meituan's security team explains cloud‑native architecture, outlines container‑escape threats from kernel bugs, vulnerable runtimes and misconfigurations, and recommends mitigation through hardened kernels, secure‑container runtimes like gVisor or Kata, rigorous patch management, and collaborative feature development to strengthen runtime protection.

DockerKata ContainersKubernetes
0 likes · 20 min read
Cloud Native Security: Container Escape and Mitigation Strategies
Refining Core Development Skills
Refining Core Development Skills
Dec 30, 2019 · Fundamentals

Unlocking Memory Secrets: Why Random IO Slows Down and How to Optimize It

This article explores the physical structure of RAM, compares random and sequential memory I/O performance, examines real‑world bandwidth versus advertised specs, delves into NUMA latency differences, and shows practical optimization techniques for PHP7 and Redis based on deep hardware and kernel knowledge.

IO performanceLinux kernelhardware fundamentals
0 likes · 8 min read
Unlocking Memory Secrets: Why Random IO Slows Down and How to Optimize It
ITPUB
ITPUB
Dec 3, 2019 · Fundamentals

How to Identify and Control Module Clock Sources in the Exynos4 Linux Kernel

This article explains how embedded Linux on Exynos4 determines which peripheral clocks are enabled or disabled, describes the struct clk representation, shows the registration process in Clock‑exynos4.c, and provides the APIs (clk_get, clk_enable, clk_disable, etc.) for querying and managing module clocks such as the LCD controller.

Clock ManagementDevice DriversExynos4
0 likes · 8 min read
How to Identify and Control Module Clock Sources in the Exynos4 Linux Kernel
Programmer DD
Programmer DD
Dec 3, 2019 · Operations

Why SSH Login Stalls on New UCloud Hosts: Entropy Delays and Kernel Bugs

A user reported extremely slow first SSH login on a UCloud “High‑Kernel Ubuntu 18.04” instance, which was traced to slow entropy‑pool initialization in the Linux kernel, a libssl 1.1.1 bug, and a kernel configuration issue, leading to a fix involving disabling MOTD or enabling CONFIG_RANDOM_TRUST_CPU.

Linux kernelSSHSystem Performance
0 likes · 11 min read
Why SSH Login Stalls on New UCloud Hosts: Entropy Delays and Kernel Bugs
ITPUB
ITPUB
Oct 8, 2019 · Fundamentals

What’s New in Linux Kernel 5.4? Key Features, Security Lockdown & exFAT Support

Linux Kernel 5.4, the final major stable release of 2019, introduces a kernel lockdown feature enhancing security, native exFAT filesystem support, and a host of hardware and driver updates including Snapdragon 855, newer AMD/Intel GPUs, Icelake Thunderbolt, VirtIO‑FS, and various filesystem and UAV improvements.

Kernel LockdownLinux kernelexFAT
0 likes · 4 min read
What’s New in Linux Kernel 5.4? Key Features, Security Lockdown & exFAT Support
Node Underground
Node Underground
Jul 20, 2019 · Cloud Native

How to Use Docker Checkpoint & CRIU for Live Container Migration

This guide walks you through enabling Docker's experimental mode, installing CRIU, building a simple Node container, creating checkpoints, and restoring containers both on the same host and on a different host, highlighting the prerequisites and limitations of live migration.

CRIUCheckpointContainer Migration
0 likes · 5 min read
How to Use Docker Checkpoint & CRIU for Live Container Migration
UCloud Tech
UCloud Tech
Mar 21, 2019 · Cloud Native

How Kernel Innovations Enable Scalable Multi‑Tenant Cloud Gateways

UCloud’s external gateway redesign leverages Linux kernel 5.0 features—lightweight tunneling, VRF, and flow offload—to replace OVS/GRE tunnels, addressing IP tunnel complexity, tenant isolation overhead, and netns performance penalties, while contributing patches back to the open‑source community.

Linux kernelMulti‑tenantVRF
0 likes · 15 min read
How Kernel Innovations Enable Scalable Multi‑Tenant Cloud Gateways
MaGe Linux Operations
MaGe Linux Operations
Mar 9, 2019 · Fundamentals

How to Master the Linux Kernel: A Practical Study Blueprint

This article shares a comprehensive, experience‑based approach to learning the Linux kernel, emphasizing building a high‑level framework first, using key textbooks strategically, balancing theory with hands‑on coding, and understanding API design and hardware interactions to accelerate mastery.

Learning MethodologyLinux kernelkernel development
0 likes · 18 min read
How to Master the Linux Kernel: A Practical Study Blueprint
21CTO
21CTO
Jan 12, 2019 · Backend Development

Remembering Li Shaohua: Insights from a Linux Kernel Pioneer

This tribute honors the late Linux kernel developer Li Shaohua, highlighting his pivotal contributions to MD RAID, block I/O, NVMe, and storage performance, while sharing personal anecdotes and technical lessons that continue to inspire kernel engineers worldwide.

Linux kernelMD RAIDNVMe
0 likes · 8 min read
Remembering Li Shaohua: Insights from a Linux Kernel Pioneer
MaGe Linux Operations
MaGe Linux Operations
Dec 2, 2018 · Fundamentals

Unlocking Linux: Deep Dive into the 2.2.5 Kernel Boot Process

This article explores the motivations for analyzing Linux kernel source code and provides a comprehensive guide to navigating the 2.2.5 i386 kernel tree, detailing the boot sequence—from BIOS to real mode initialization, bootsect loader, setup, and protected‑mode startup—while highlighting key files, structures, and parameters.

Linux kerneli386operating system
0 likes · 22 min read
Unlocking Linux: Deep Dive into the 2.2.5 Kernel Boot Process
UCloud Tech
UCloud Tech
Nov 15, 2018 · Cloud Computing

How 25G SmartNICs Boost Cloud VM Networking Tenfold with Open vSwitch

This article examines the rapid adoption of 25G SmartNICs for cloud workloads, compares major vendor solutions, explains why an Open vSwitch‑based TC Flower offload design was chosen, and details the practical challenges and performance gains achieved when deploying the solution in a public‑cloud environment.

25G networkingLinux kernelOpen vSwitch
0 likes · 13 min read
How 25G SmartNICs Boost Cloud VM Networking Tenfold with Open vSwitch
JD Tech
JD Tech
Sep 20, 2018 · Big Data

Optimizing Local Storage Systems for Large‑Scale Hadoop HDFS Clusters

This article explains the architecture of Hadoop HDFS, identifies performance bottlenecks in page cache and metadata handling on DataNodes, and presents four practical optimization techniques—including cache‑buffer separation, barrier disabling, directory restructuring, and real‑time monitoring—demonstrating significant throughput and latency improvements in large‑scale clusters.

HDFSHadoopLinux kernel
0 likes · 14 min read
Optimizing Local Storage Systems for Large‑Scale Hadoop HDFS Clusters
360 Tech Engineering
360 Tech Engineering
Sep 14, 2018 · Fundamentals

Understanding the Linux Kernel list.h Linked List Implementation

This article explains the classic Linux kernel list linked‑list data structure, covering its definition, file locations, core operations such as initialization, insertion, deletion, replacement, moving, splitting and merging, the list_entry macro, usage examples, and important multithreading considerations.

C ProgrammingData StructuresLinux kernel
0 likes · 5 min read
Understanding the Linux Kernel list.h Linked List Implementation
MaGe Linux Operations
MaGe Linux Operations
Aug 11, 2018 · Fundamentals

Mastering Linux Kernel Learning: Proven Strategies and Essential Resources

This article shares a personal yet systematic approach to learning the Linux kernel, emphasizing the importance of building a high‑level framework before diving into code, recommending key textbooks, discussing language considerations, API insights, and encouraging hands‑on experimentation to deepen understanding.

BooksLearning StrategiesLinux kernel
0 likes · 18 min read
Mastering Linux Kernel Learning: Proven Strategies and Essential Resources
360 Zhihui Cloud Developer
360 Zhihui Cloud Developer
May 22, 2018 · Backend Development

Why Short TCP Connections Fail: Decoding Errors 110 & 99 and Fixes

When clients frequently use short TCP connections they often encounter error 110 (connection timeout) and error 99 (cannot assign requested address), which stem from TIME‑WAIT port exhaustion and server listen‑queue overflow, and this article explains the causes and practical solutions.

EADDRNOTAVAILLinux kernelTCP
0 likes · 9 min read
Why Short TCP Connections Fail: Decoding Errors 110 & 99 and Fixes
Didi Tech
Didi Tech
May 18, 2018 · Backend Development

Understanding the Thundering Herd Problem in Linux and Nginx

The article explains the thundering herd problem where many processes wake for a single event, describes Linux’s kernel fixes for accept() and partial epoll solutions, and details how Nginx avoids the issue using a custom inter‑process accept mutex and lock design.

Linux kernelLockingNGINX
0 likes · 14 min read
Understanding the Thundering Herd Problem in Linux and Nginx
Tencent Database Technology
Tencent Database Technology
May 17, 2018 · Operations

Analysis of ext4 Soft Lockup Caused by Extent Status LRU Lock Contention in Linux 3.10

This article examines a Linux 3.10 kernel soft‑lockup bug where the ext4 extent‑status LRU spin‑lock is held for over 20 seconds under memory pressure, explains the ext4 delayed‑allocation mechanism, block lookup process, extent‑status cache shrinkage, and presents the community's mitigation approach.

LRU spin lockLinux kernelext4
0 likes · 12 min read
Analysis of ext4 Soft Lockup Caused by Extent Status LRU Lock Contention in Linux 3.10
ITFLY8 Architecture Home
ITFLY8 Architecture Home
Apr 25, 2018 · Operations

Mastering C10K: Modern Techniques to Scale Server Concurrency

This article reviews the historical C10K challenge, explains IO model improvements like epoll, kqueue and IOCP, and details practical Linux performance optimizations such as CPU and memory affinity, RSS/RPS/RFS/XPS, IRQ handling, kernel tuning, and hardware utilization for high‑concurrency servers.

C10KCPU affinityHigh concurrency
0 likes · 21 min read
Mastering C10K: Modern Techniques to Scale Server Concurrency
Qunar Tech Salon
Qunar Tech Salon
Mar 21, 2018 · Operations

Root Cause Analysis and Optimization of Network Packet Loss in High‑Traffic Redis Services

The article investigates why massive Redis deployments experience network packet loss despite using 10 Gbps NICs, explains how Linux kernel counters such as net.if.in.dropped are derived from /proc/net/dev, walks through the driver‑to‑kernel processing path, and proposes CPU‑affinity, interrupt‑affinity and NUMA‑aware tuning to eliminate the drops.

CPU affinityLinux kernelPacket loss
0 likes · 28 min read
Root Cause Analysis and Optimization of Network Packet Loss in High‑Traffic Redis Services
Meituan Technology Team
Meituan Technology Team
Mar 15, 2018 · Operations

Root Cause Analysis and Optimization of Network Packet Loss in High‑Traffic Redis Services

Through kernel‑level analysis we discovered that Redis packet loss stemmed from rx_dropped buffer exhaustion caused by interrupt‑handling backlogs, and resolved it by assigning NIC interrupts to specific cores on one NUMA node while binding Redis processes to the other, eliminating loss under dual‑10 GbE load.

Linux kernelNAPINetwork
0 likes · 33 min read
Root Cause Analysis and Optimization of Network Packet Loss in High‑Traffic Redis Services
ITPUB
ITPUB
Oct 22, 2017 · Fundamentals

Why Can't Interrupt Handlers Sleep? Understanding Linux Kernel Sleep and Wakeup Mechanisms

This article explains the purpose and mechanics of process sleep in the Linux kernel, detailing how wait queues and wake‑up functions operate, why sleeping in atomic contexts such as interrupt handlers or while holding spinlocks is unsafe, and demonstrates the resulting deadlock with a sample driver.

Linux kernelSpinlockinterrupt context
0 likes · 16 min read
Why Can't Interrupt Handlers Sleep? Understanding Linux Kernel Sleep and Wakeup Mechanisms
dbaplus Community
dbaplus Community
May 31, 2017 · Operations

Why Docker Hosts Crashed: Tracing Kernel Null‑Pointer Bugs and the Fix

The article recounts a half‑year investigation of a high‑performance proxy cluster whose Docker hosts repeatedly crashed due to kernel null‑pointer dereferences, detailing log analysis, three faulty hypotheses, extensive web research, kernel and Docker upgrades, and the final operational lessons learned.

DockerLinux kernelNull pointer dereference
0 likes · 14 min read
Why Docker Hosts Crashed: Tracing Kernel Null‑Pointer Bugs and the Fix
MaGe Linux Operations
MaGe Linux Operations
May 15, 2017 · Information Security

Critical Linux Kernel UDP Bug (CVE-2016-10229) Enables Remote Code Execution

An unauthenticated remote attacker can exploit a flaw in Linux kernel versions prior to 4.5’s udp.c, using crafted UDP packets with MSG_PEEK to trigger an unsafe checksum calculation, achieving arbitrary code execution and potential privilege escalation, though the vulnerability’s impact is limited due to rare MSG_PEEK usage.

CVE-2016-10229Linux kernelRemote Code Execution
0 likes · 4 min read
Critical Linux Kernel UDP Bug (CVE-2016-10229) Enables Remote Code Execution
ITPUB
ITPUB
Feb 16, 2017 · R&D Management

Linus Torvalds on Project Management: Why Users Matter More Than Code

In this interview, Linus Torvalds shares hard‑earned lessons on software project management, emphasizing personal responsibility, the primacy of users over code quality, the limited role of tools, and how the Linux kernel mailing list keeps contributors aligned, offering timeless advice for developers and teams.

Linus TorvaldsLinux kernelOpen-source
0 likes · 9 min read
Linus Torvalds on Project Management: Why Users Matter More Than Code
ITPUB
ITPUB
Sep 28, 2016 · Backend Development

Why Enabling Multipath Routing Shrinks the FIB Table: Uncovering a Hidden Linux Kernel Bug

A long‑standing Linux kernel bug causes the FIB routing hash table to shrink from 256 to 2 entries when multipath routing is enabled, leading to performance degradation; the article explains the faulty macros, traces the communication with the original authors, and advises applying the upstream fix or patching locally.

FIBLinux kernelPATCH
0 likes · 3 min read
Why Enabling Multipath Routing Shrinks the FIB Table: Uncovering a Hidden Linux Kernel Bug
MaGe Linux Operations
MaGe Linux Operations
Aug 26, 2016 · Fundamentals

Unlocking Linux Kernel Magic: How container_of Retrieves Struct Addresses

This article explains the Linux kernel’s widely used container_of macro, showing how it converts a member’s address into the containing structure’s base address through examples, typeof and offsetof usage, and demonstrates the underlying calculations with clear code snippets and illustrations.

C macroLinux kernelSystems Programming
0 likes · 5 min read
Unlocking Linux Kernel Magic: How container_of Retrieves Struct Addresses
ITPUB
ITPUB
Aug 12, 2016 · Fundamentals

Why Do Spinlocks Behave Differently on UP vs SMP Linux Kernels?

The article explains how Linux spinlocks, originally designed for SMP systems, operate in UP kernels, why CONFIG_DEBUG_SPINLOCK changes their behavior, and which spinlock variants should be used in different interrupt and preemption contexts.

CONFIG_DEBUG_SPINLOCKLinux kernelSpinlock
0 likes · 14 min read
Why Do Spinlocks Behave Differently on UP vs SMP Linux Kernels?
ITPUB
ITPUB
May 31, 2016 · Fundamentals

Can the 2038 Unix Bug Threaten Linux? A Deep Dive into the Time Overflow

The article revisits the historic Y2K panic and explains how the same kind of overflow, known as the 2038 Unix bug, threatens Linux systems as their 32‑bit time counters will roll over on January 19, 2038, potentially causing widespread date‑related failures.

2038 bugLinux kernelUnix
0 likes · 4 min read
Can the 2038 Unix Bug Threaten Linux? A Deep Dive into the Time Overflow
Tencent Music Tech Team
Tencent Music Tech Team
May 20, 2016 · Fundamentals

In‑Depth Analysis of TCP Connection Timeout, TIME_WAIT, Nagle Algorithm and Kernel Parameters

This article examines three common TCP issues—missing client‑side socket timeouts leading to monitor‑killed processes, excessive TIME_WAIT sockets after service failures and their kernel tunables, and 40 ms keep‑alive latency caused by Nagle and delayed ACK—explaining kernel behavior and offering practical configuration fixes.

Linux kernelNagle algorithmTCP
0 likes · 19 min read
In‑Depth Analysis of TCP Connection Timeout, TIME_WAIT, Nagle Algorithm and Kernel Parameters
ITPUB
ITPUB
Dec 8, 2015 · Fundamentals

Why the Linux Kernel Thrives: Architecture, Modularity, and Core Subsystems Explained

This article explains how the Linux kernel’s layered architecture, modular design, and well‑defined subsystems such as the process scheduler, memory manager, virtual file system, and network interface enable massive volunteer collaboration, extensibility, and continuous evolution of the operating system.

Linux kernelMemory managerOS Architecture
0 likes · 19 min read
Why the Linux Kernel Thrives: Architecture, Modularity, and Core Subsystems Explained
Meituan Technology Team
Meituan Technology Team
Apr 1, 2015 · Cloud Native

Understanding Linux cgroups: Concepts, Hierarchy, and Usage

Linux cgroups are a kernel feature that organizes processes into hierarchical control groups, allowing fine‑grained limits, accounting, and isolation of CPU, memory, I/O, network and devices via subsystems such as cpu, memory, cpuset, blkio, and others, and are accessed through a virtual filesystem for configuring and managing resource constraints, underpinning containers and cloud platforms.

Cloud NativeContainersLinux kernel
0 likes · 15 min read
Understanding Linux cgroups: Concepts, Hierarchy, and Usage