摘要：本文测试时间时2020.12.06 测试的mysql版本是community版本8.0.22 首先指出一个select ...for update的一个大家很容易产生的错误理解："for update可以锁存在的和不存在的记录，同一个索引字段的同样的值一定会block住。" 这句话对也不对。对是指它 阅读全文

摘要：mutex( x lock): when a mutex lock is obtained, others cannot obtain the same mutex while the lock is not freed. shared lock( s lock): when a shared lo 阅读全文

摘要：libev First let's talk about libev, it is a lib used in ss. The coding style of libev is ugly. To see man page of libev by: man ./ev.3 3 files need to 阅读全文

摘要：SACK: (selective ack), it is an option added to normal ack packets. Normally sack can specify at most 4 groups of seq_start, seq_end. Meaning bytes at 阅读全文

摘要：According to RedHat accessories, TCP_NODELAY: each call to write(fd, buf...) will be sent out as packet. This leads to poor overall performance when m 阅读全文

摘要：Before using stap, the kernel-debuginfo-$(uname -r), kernel-debuginfo-common-$(uname -m)-$(uname -r) and kernel-devel-$(uname -r) should be installed. 阅读全文

摘要：However till now golang's debug functionality seems far from okay. During debug you cannot print map objects. And also from debugging related aspects, 阅读全文

摘要：Before preceding, several things need to be checked: There are too many tutorials on how to build with ct-ng, I only list several useful steps for fut 阅读全文

摘要：1. malloc memory should always use the following form: 2. memset memory to 0 should use the form: 3. malloc(0) might also return address which is non- 阅读全文

摘要：My summary after reading this. Before doing large memory writes: _mm*_stream_s[i,s,d]*: non-temporal memory store: When data is produced and not (imme 阅读全文

摘要：ioctl is used in communication with modules of Linux. Module: User space In case of Makefile is needed: 阅读全文

摘要：some frequently used AC macros: AC_INIT :must AC_OUTPUT :must AC_PREREQ :determine ac version so that needed features are included AC_CONFIG_SRCDIR :d 阅读全文

摘要：Sometimes we build a program as release and when debugging, some variables cannot be printed out, and displayed as optimized out. That is because the 阅读全文

摘要：from here. php basics in PHP, variables are defined as $_alphanum variables should always prefixed a $ variables defined/assigned outside of a functio 阅读全文

摘要：To use composer, first system must satisfy php environment: To install composer, try either: enable packagist repo globally: [its speed seems not fast 阅读全文

摘要：SNMP is a protocol that enables server remote-info-exchange. Which according to wikipedia: it [collecting and organizing information about managed dev 阅读全文

摘要：Maven, is actually a java project manager.. Installing maven in windows need to set system environment vars like JAVA_HOME and PATH.. And it is rather 阅读全文

摘要：again 阅读全文

摘要：if using dpdk, then OvS' datapath folder is ignored. Only OvS' userspace code are in use. According to manpages of ovs-vsctl/ovs-dpctl, it says that t 阅读全文

摘要：before anything.. sizeof is an operand! sizeof is an operand! sizeof is an operand! 重要なことは三回にしませんね！ int *ptr; sizeof *ptr; = sizeof (int); the followi 阅读全文