三叁

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： 上级给派了个实习生给我，这个实习生首先能力是怎样还不知道。 1. 如果我想带他，那他必须得会console吧，如果他跟其他同事一样用vs，那我就不太好带了； 2. 我帮他装vim及配件以及帮他装plugin教他快捷键？我别的活别干了。其实说实话，之前在智明星通，就是因为导师对我爱答不理，啥都要自学就 阅读全文

摘要： First confirm that you have root privilege. Second check the config of kernel that you have the configs on: Last you confirm you have your debugfs/tra 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： How the algorithm and formula are implemented seem trivial, the most important of the passage's idea is the definition of 'conservation of packets'. F 阅读全文

摘要： At kernel init, each logical core has a thread called ksoftirq/%d running. These threads are brought up by the initial function net_dev_init(). While 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： In linux mm folder, there are 3 files that about kmalloc/kmem, slab/slub/slob, where slab.c defines general memory usage, slub.c defines modern memory 阅读全文