Jaeho Kim

* My paper(FAST'15) was mentioned at some articles as below. - Whs SSDs don't perform (http://www.zdnet.com/article/why-ssds-dont-perform/) - Why it's hard to meet SLAs with SSDs (https://storagemojo.com/2015/06/03/why-its-hard-to-meet-slas-with-ssds/)  - SSDs struggle in VMs thanks to garbage collection (https://www.extremetech.com/computing/206638-researchers-ssds-struggle-in-virtual-machines-thanks-to-garbage-collection)  - Research finds SSDs struggle in VM environment! (https://storageservers.wordpress.com/2015/05/29/research-finds-ssds-struggle-in-virtual-servers-environment/)

- set cscope editor ~root/.bashrc  export CSCOPE_EDITOR=/usr/bin/vim * 부팅 순서 변경 - grub2-editenv list ;  - grub2-set-default 2 ;  * Start Dropbox on Starup Follow these steps to make Dropbox start up each time. Click on the Ubuntu "Dash" icon Type  Startup Applications  in the Dash search area Click on the "Startup Applications" ico Click "Add" button For "Name:", type  Dropbox For "Command:", type  /home/{your-username}/.dropbox-dist/dropboxd For "Comment:", this can be left blank Click "Add" button Click "Close" button Restart your computer * Some commands for network and security  - ifdown enp2s0  - ifup enp2s0  - yum install fail2ban  - systemctl enable fail2ban  - service fail2ban status  - service fail2ban start  - service fail2ban status

* Ftrace 1 https://lwn.net/Articles/365835/ * Choosing a Linux Tracer http://www.brendangregg.com/blog/2015-07-08/choosing-a-linux-tracer.html * Monitoring dmesg in real time  #watch "dmesg | tail -f -n 40"  ; show 40 line

There are lots of monitoring utilities for Linux performance. Here is link for useful tools. https://blog.serverdensity.com/80-linux-monitoring-tools-know/  - System Monitoring Tools: top, htop, atop, apachetop,  ftptop, mytop, powertop, iotop  - Network related monitoring: ntopng, iftop, etc.

I received the Best Paper Award at the 2016 Korean Conference on Semiconductors from the SK Hynix. Best paper award

How to Write Technical Articles Collected Advice on Research and Writing How to Get Your Systems Paper Accepted How to read Computer Science papers The links are from https://sites.google.com/site/youkim/

* 파일 크기순으로 정렬하여 리스팅 (현재 디렉터리 이하) #du -ah . | grep -v "/$" | sort -rh

1. Quick sanity test  - hdparm -tT --direct /dev/sdc       ;; -t: perform device read timings, -T: perform cache read timings ;; --direct: use O_DIRECT to bypass page cache for timings

* Useful command on Linux = iostat = iostat 명령어를 통한 storage statistics 알아보기 #iostat -x -c 1  ;1초마다 extended statistics와 CPU utilization 보여줌 #man iostat = dmesg = $watch "dmesg | tail -f -n 30" ;dmesg 실시간 출력 30 lines

Event type of blktrace  - A : remap  - Q: IO is queued  - G: a request struct allocated (get request)  - P: the queue is plugged  - I: the IO is scheduled  - U: the queue is unplugged  - D: the IO is dispatched to the device  - C: the IO is completed (C) Source code in Linux kernel  - location: kernel/trace/blktrace.c  - blk_fill_rwbs ( ) : set F, W, D, R, N, A, S, M, E flag  - blktrace.c 파일에 register_block_xx(blk_add_trace_xx, NULL) 함수로 등록하고 외부에서 사용할때는 block/blk-core.c 파일에서 trace_block_xx(q, rq) 함수로 block layer를 tracing한다. Link for explaining blktrace  -  http://brooker.co.za/blog/2013/07/14/io-performance.html  -  http://studyfoss.egloos.com/tag/blktrace/page/1  -

http://cseweb.ucsd.edu/classes/wi11/cse141/  - Computer Architecture class by Steven Swanson at UCSD http://cseweb.ucsd.edu/classes/fa11/cse240A-a/ - Computer Architecture class for graduate by Steven Swanson at UCSD