--- tags: Linux2020 高效能網頁伺服器 tiles: 高效能網頁伺服器 - lwan's clock --- contributed by < `YLowy` > # lwan's clock ## 這個會一直動的時間怎麼做到的? ![](https://i.imgur.com/wWARLpO.png) https://www.jwz.org/xdaliclock/ lwan 利用 keep alive 的 chunked-encoding 製作一個 never-ending GIF。 :::info 不要嘗試下載他這個 gif，下載不完的。 ::: 這邊我們會拆成兩塊分析 : >**1. keep alive 的 connection 在 lwan server 中的運做?** >**2. lwan 如何回應此 never-ending GIF 給 Client ?** ## 1. keep alive 的 connection 在 lwan server 中的運做? //todo ## 2. lwan 如何回應此 never-ending GIF 給 Client ? //todo
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eBPF

Debug always make developer sad, especially in a big system. How to debug in Linux Kernel? Tracing In early kernel patch, we have some tracing tools, e.g. strace, gdb. They are all based on the old tracing system call: ptrace. GDB gdb -q test.o strace

7/8/2022
How io_uring and eBPF Will Revolutionize Programming in Linux

refer: https://thenewstack.io/how-io_uring-and-ebpf-will-revolutionize-programming-in-linux/ io_uring Classic IO system call For UDP's receive system call, it can be divided into two stages, wait for data and copy data to user space. Kernel offered the following blocking system calls to deal with file descriptors, be they storage files or sockets: size_t read(int fd, void *buf, size_t count); size_t write(int fd, const void *buf, size_t count);

6/15/2022
Optimed Strlen (cont.)

1. uclib vs glib uclib ->https://git.uclibc-ng.org/git/uclibc-ng.git uClibc-ng is a small C library for developing embedded Linux systems. It is much smaller than the GNU C Library, but nearly all applications supported by glibc also work perfectly with uClibc-ng. In strlen() function, the "finding zero in long size string" is different between glib and uclib. See Here //uclib

6/6/2022
Optimed Strlen

We often use the strlen(str) function to get the length of the string. This is broad-use, and simply implemented. In C, we cannot consider a string as an object. We need to find the '\0'(NULL) character to determine the end of the string. C11 6.4.5 6. a byte or code of value zero is appended to each multibyte character sequence that results from a string literal or literals. C11 7.1.1 A string is a contiguous sequence of characters terminated by and including the first null character. The term multibyte string is sometimes used instead to emphasize special processing given to multibyte characters contained in the string or to avoid confusion with a wide string. A pointer to a string is a pointer to its initial (lowest addressed)

5/22/2022
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