Kernel - Page Frame 回收
· ☕ 4 分钟
From [Understanding The Linux Kernel] Page Frame 回收 之前我们了解到，Linux 倾向用最多的内存做 Page Cache。这使我们不得不考虑如何在内存不足前回收内存。问题是，回收内存的程
寫點東西吧，懒人。
Kernel - Pagecache
· ☕ 1 分钟
简介 page cache 存放的数据的类型 普通的文件 目录数据 直接读取自 block device file 的数据 已经被swap out的用户进程内存的数据（可以强制内核在page cahce中
Kernel - Pagecache - Core
· ☕ 3 分钟
address_space 数据结构 Page cahce 的核心数据结构是 addrees_space。一般来说，每个 inode （Kernel 用来存放文件元信息的内存中的数据结构，可以视为一个文
· ☕ 4 分钟
https://tenzir.com/blog/production-debugging-bpftrace-uprobes/
https://shaharmike.com/cpp/vtable-part1/
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 #include <iostream> class Parent { public: virtual void Foo() {} virtual void FooNotOverridden() {} }; class Derived : public Parent { public: void Foo() override {} }; int main() { Parent p1, p2; Derived d1, d2; std::cout << "done" << std::endl; } $ # compile our code with debug symbols and start debugging using gdb $ clang++ -std=c++14 -stdlib=libc++ -g main.
· ☕ 5 分钟
Terminology Cluster: a logical service with a set of endpoints that Envoy forwards requests to.
Downstream: an entity connecting to Envoy. This may be a local application (in a sidecar model) or a network node. In non-sidecar models, this is a remote client.
Endpoints: network nodes that implement a logical service. They are grouped into clusters. Endpoints in a cluster are upstream of an Envoy proxy.
Filter: a module in the connection or request processing pipeline providing some aspect of request handling.
· ☕ 1 分钟
https://istio.cn/t/topic/299
Envoy源码分析之Dispatcher：https://developer.aliyun.com/article/659277
线程相关 Misc：
Envoy进程由一个Main Thread和多个Worker Thread 组成 每个Main和Worker包含一个eventloop，所有的处理都是由eventloop触发开始 Main负责xDS等功能，Worker负责处理连接和请求 当一个client向Envoy建立连接的时候，因为所有Worker的EventLoop都注册了listening fd(启用SO_PORTREUSE除外)，会由内核决定分配给哪个Worker 当一个下游client连接到了Envoy，在保持连接不断的情况下，会和同一个Worker进行通讯
· ☕ 2 分钟
HTTP/1.1 Header Casing https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_conn_man/header_casing#config-http-conn-man-header-casing
When handling HTTP/1.1, Envoy will normalize the header keys to be all lowercase. While this is compliant with the HTTP/1.1 spec, in practice this can result in issues when migrating existing systems that might rely on specific header casing.
To support these use cases, Envoy allows configuring a formatting scheme for the headers, which will have Envoy transform the header keys during serialization.
To configure this formatting on response headers, specify the format in the http_protocol_options.