Deep dive into Kernel

iptables 를 활용한 port forwarding iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to-destination 192.0.2.2 iptables -t nat -A PREROUTING -i em1 -p tcp --dport 8082 -j DNAT --to 192.168.0.83:80

Intel NVMe 의 Product 번호를 보면3x00 시리즈와 750 시리즈가 있는데, 3x00 시리즈는 서버향 NVMe 이며 750 시리즈는 클라이언트향이다. PCI 정보08:00.0 Non-Volatile memory controller: Intel Corporation Device 0953 (rev 01) (prog-if 02) Subsystem: Intel Corporation Device 3702 Flags: bus master, fast devsel, latency 0, IRQ 16 Memory at ef110000 (64-bit, non-prefetchable) [size=16K] Expansion ROM at ef100000 [disabled] [size=64K] Capabilities..

jemalloc Constructor jemalloc_constructor->malloc_init:note right of malloc_init: unlikely(!malloc_initialized())malloc_init->malloc_init_hard:malloc_init->malloc_thread_init:

Constructor 와 Destructor 는 main 함수가 실행되기 전에 호출되는 special function 이다.main function 이 load 되기 전에 __libc_csu_init 함수에서 constructor 들이 호출된다. 포멧:__attribute__((constructor))__attribute__((destructor))__attribute__(constructor (PRIORITY)))__attribute__(destructor (PRIORITY))) 예제:#include void begin (void) __attribute__((constructor));void end (void) __attribute__((destructor)); int main(){ printf("\n..

build git clone https://github.com/jemalloc/jemalloc.git cd jemalloc(사전 준비) apt-get install docbook-xsl(빌드)./autogen.shmake distmakemake install testg++ test.c -I/usr/local/include -ljemalloc test.c#include #include voiddo_something(){ // Leak some memory. malloc(sizeof(int)); malloc(512);} intmain(int argc, char **argv){ malloc_stats_print(NULL, NULL, NULL); for (int i = 0; i < 500; ++i) { do_s..

ReferenceAnatomy of a Program in Memoryhttp://duartes.org/gustavo/blog/post/anatomy-of-a-program-in-memory/ Linux x86 Program Start Uphttp://dbp-consulting.com/tutorials/debugging/linuxProgramStartup.html [glibc] CSU (C start up) routineshttp://egloos.zum.com/studyfoss/v/5283161

In a program or code, it is necessary to identify kernel version.For example, vlan_tx_tag_get is changed to skb_vlan_tag_get in kernel 4.0.0.We can do by using LINUX_VERSION_CODE and KERNEL_VERSION(a,b,c). In these case, we need to switch to new API. #include #if ( LINUX_VERSION_CODE >= KERNEL_VERSION(4,0,0) ) /* vlan_tx_xx functions got renamed to skb_vlan */ #define vlan_tx_tag_get skb_vlan_ta..

http://forum.xda-developers.com/galaxy-s3/general/ubuntu-backtrack-i9300-samsung-galaxy-s3-t1700228

Making B+-Trees Cache Conscious in Main Memory: https://www.cs.duke.edu/courses/spring03/cps216/papers/rao-ross-2000.pdf Cache-Conscious Data Structureshttp://research.microsoft.com/en-us/um/people/trishulc/papers/cache-conscious.pdf [ACM SIGPLAN 1999] Cache-Conscious Structure Layerhttp://research.microsoft.com/en-us/um/people/trishulc/papers/layout_distr.pdf Cache-Oblivious Dynamic Search Tree..

TX Ring Desc Architecture Xmit Frame - device driver receive sk_buff from kernel - find tx_buffer_info which can be used - fill tx_buffer_info based on skb's info - update next_to_use (cf. may be used more than 1 index, if the size of skb is larger than 1 page) - notify tx_ring to H/W 추가 설명- 전송할 패킷이 존재할 때, device driver는 ximt 을 하며, 이는 descriptor 의 tail에 쓰고, tail의 값을 업데이트 한다. (아래 TDT register)- H..