随笔分类 -  Kernal Related

ftrace: tracing linux function calls
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

posted @ 2018-10-28 16:26 三叁 阅读(197) 评论(0) 推荐(0)

TCP: Nomenclatures
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

posted @ 2018-09-04 01:46 三叁 阅读(187) 评论(0) 推荐(0)

Reflection: Congestion Avoidance and Control
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

posted @ 2018-09-03 07:38 三叁 阅读(705) 评论(0) 推荐(0)

Linux Network: Receive side notes
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

posted @ 2018-08-31 05:54 三叁 阅读(244) 评论(0) 推荐(0)

TCP options: Intro
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

posted @ 2018-08-30 20:58 三叁 阅读(133) 评论(0) 推荐(0)

slab/slub/slob: Linux kernel memory mngmt
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

posted @ 2018-07-24 11:38 三叁 阅读(356) 评论(0) 推荐(0)

Systemtap: learning notes
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

posted @ 2018-07-15 18:48 三叁 阅读(283) 评论(0) 推荐(0)

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

posted @ 2018-05-03 17:56 三叁 阅读(530) 评论(0) 推荐(0)

TSC: Intro & Comments
摘要:From wiki quote: The Time Stamp Counter (TSC) is a 64-bit register present on all x86 processors since the Pentium. It counts the number of cycles sin 阅读全文

posted @ 2018-01-20 12:12 三叁 阅读(222) 评论(0) 推荐(0)

NIC Bonding: 2 nic port as 1 interface
摘要:The following is concluded from here. Consider we have 2 interfaces: eth0 & eth1 bond the two interface: in ifcfg-eth0/ifcfg-eth1: remove IP/MASK/GW/U 阅读全文

posted @ 2016-12-08 15:19 三叁 阅读(468) 评论(0) 推荐(0)

ramfs/tmpfs: Linux RAM filesystems
摘要:Previously in windows, I uses ramdisk, to accelerate chrome browsing. However, in linux, this is made possible by tmpfs/ramfs already by default. Also 阅读全文

posted @ 2016-11-19 17:02 三叁 阅读(299) 评论(0) 推荐(0)

Learning BSD.sys/queue.h
摘要:This file includes 4 data-structures.. Insteresting because they are written in 1994.. to make it easier using the structures.. LIST: the common usage 阅读全文

posted @ 2016-09-09 17:29 三叁 阅读(984) 评论(0) 推荐(0)

ABI & API
摘要:API defines the programning language and function entry point, arguments type, order. ABI defines the programming compiled version to be according to 阅读全文

posted @ 2016-08-05 17:49 三叁 阅读(178) 评论(0) 推荐(0)

Setting DPDK+OVS+QEMU on CentOS
摘要:Environment Build Step: these packages are needed for building dpdk+ovs: First download latest dpdk & ovs :http://dpdk.org/download git clone https:// 阅读全文

posted @ 2016-07-10 13:22 三叁 阅读(1804) 评论(0) 推荐(1)

Newly Setting up a CentOS-7 system
摘要:yum install -y epel-release glibc.i686 libtools vim clang git autoconf automake w3m glibc screen the most import sentence I learned in meeting compili 阅读全文

posted @ 2016-07-10 11:19 三叁 阅读(265) 评论(0) 推荐(0)

Converting between IEEE 754 and Float (Format related
摘要:The float can be converted to well known single-precision IEEE 754 number, why 754? It's the standard representation of single-precision numbers, used 阅读全文

posted @ 2016-04-22 15:58 三叁 阅读(324) 评论(0) 推荐(0)

Java Concurrent Topics
摘要:To prevent Memory Consistency Errors(MCEs), it is good practice to specify synchronized class specifier, and mark all the related methods as synchroni 阅读全文

posted @ 2016-04-15 15:23 三叁 阅读(166) 评论(0) 推荐(0)

Java BigDecimal Class
摘要:Using BigDecimal to perform precise calculations with floats. BigDecimal is a class type. So declare/construct one BigDecimal is in the form like: Do 阅读全文

posted @ 2016-04-12 16:24 三叁 阅读(290) 评论(0) 推荐(0)

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