2020.09.05.Meeting Sync

[iamrootbug]

다음주 진도계획

p114 ~ p163

time schedule

한시간씩 진행 (50분 진행 / 10분 휴식)
15:00 - 18:00
18:00 - 19:00 휴식
19:00 - 21:30
21:30 - 22:00 정리 & 다음주 진도 계획
이번주 진도 p70~p114

ch3. 테스크 관리 :: 6.상태 전이

task_uninterruptible vs task_killable : signal
https://stackoverflow.com/questions/767551/how-to-stop-uninterruptible-process-on-linux

current task level ?
cs register 의 최하위 비트 2개 = 권한, ring CPL DPL
https://en.wikipedia.org/wiki/X86_memory_segmentation
user level = 0b11
kernel level = 0b00

interrupt vs trap vs signal
https://en.wikipedia.org/wiki/Trap_(computing)
https://stackoverflow.com/questions/13341870/signals-and-interrupts-a-comparison
trap = syscall, breakpoint, cpu에 의도된 멈춤? 전달?
interrupt = exception, divide by zero, page fault. cpu 에 의도되지 않은 멈춤?
signal = OS kernel <-> process 하나의 통신. ipc일종
https://en.wikipedia.org/wiki/Signal_(IPC)

union keyword in c
멤버 변수간 메모리 공간 공유

https://m.blog.naver.com/PostView.nhn?blogId=imbin_&logNo=221330417695&proxyReferer=https:%2F%2Fwww.google.com%2F

x86 calling convention :: system call
eax에 시스템콜 번호를 넣고
int $0x80을 호출한다.
https://stackoverflow.com/questions/47692516/what-is-the-use-of-eax-register-in-the-context-of-system-calls-in-linux

sched_domain
sched_group 을 하드웨어적 특성에 따라 분류.
https://www.kernel.org/doc/html/latest/scheduler/sched-domains.html
https://stackoverflow.com/questions/14229793/what-does-struct-sched-domain-stands-for-in-include-linux-sched-h-scheduling-do
http://jake.dothome.co.kr/sched-domain/

RT 스케줄러
SCHED_FIFO, SCHED_RR
http://jake.dothome.co.kr/rt-scheduler/

일반 스케줄러
CFS (completely fair scheduler) vruntime Time Slice
http://jake.dothome.co.kr/cfs/

Context, 문맥
registers pc ebx ..

SMP vs AMP
SMP = 요즘 일반적인 cpu
AMP = arm bit.LITTLE cpu
https://blogs.sw.siemens.com/embedded-software/2010/06/07/amp-vs-smp/

ch4. 메모리 관리

32bit -> 2^32 = 2^2 * (2^10)^3 = 4 * 1e9 => 4GB

물리 메모리
노드 > 존 > 페이지.
NUMA = 복수의 노드 존재.
존 종류 : ZONE_DMA, ZONE_NORMAL ...
http://jake.dothome.co.kr/zone-types/
Buddy 큰 사이즈
Slab 작은사이즈 cache
http://jake.dothome.co.kr/buddy-alloc/
http://jake.dothome.co.kr/slub/

가상메모리
task_struct > mm_struct > vm_area_struct
cat /proc/self/maps
MMAP(2) MAP_ANONYMOUS MAP_SHARED MAP_PRIVATE
https://man7.org/linux/man-pages/man2/mmap.2.html