<div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">연구를 위해서 프로그램 개발 중인데, 멀티 프로세서를 이용해서 여러 실험을 동시에 돌려야 합니다.</div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">처음엔 자바에서 멀티 스레드로 처리 했는데, 좀 더 실험 속도를 올리려고 C++로 다시 만들었어요</div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">C++는 OpenMP를 이용하면 멀티코어를 쓸 수 있다고 해서 OpenMP 루프 병렬화로 개발을 완료 했습니다.</div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">그런데 스레드 수를 늘리면 늘릴수록 각 루프가 배로 느려지네요 ㅠㅠ CPU 사용량 보면 코어 배분도 잘 되는거 같은데</div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">스레드 수 1개<br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><img width="800" height="592" class="chimg_photo" style="border:medium;" alt="1.png" src="http://thimg.todayhumor.co.kr/upfile/201801/15150432901ea873ec37ef4f9d93f39df78ea13d42__mn271740__w999__h739__f152878__Ym201801.png" filesize="152878"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">스레드 수 2개</div></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><img width="800" height="579" class="chimg_photo" style="border:medium;" alt="2.png" src="http://thimg.todayhumor.co.kr/upfile/201801/15150432910654d9c7e4224e98b0755cbd1a4d5d82__mn271740__w998__h722__f155470__Ym201801.png" filesize="155470"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">스레드 수 4개</div></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><img width="800" height="613" class="chimg_photo" style="border:medium;" alt="4.png" src="http://thimg.todayhumor.co.kr/upfile/201801/1515043293ba81bac68f07463f86b992297b65a3f0__mn271740__w961__h736__f157179__Ym201801.png" filesize="157179"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">스레드 수 8개</div></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><img width="800" height="559" class="chimg_photo" style="border:medium;" alt="8.png" src="http://thimg.todayhumor.co.kr/upfile/201801/1515043294f73a4e14af34451ab356c612ad2ada88__mn271740__w962__h672__f150070__Ym201801.png" filesize="150070"></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><br></div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;">16개</div> <div style="font:400 12px/18px '굴림';margin:0px;text-align:left;color:#000000;text-transform:none;text-indent:0px;letter-spacing:normal;text-decoration:none;word-spacing:0px;white-space:normal;background-color:transparent;"><img width="800" height="536" class="chimg_photo" style="border:medium;" alt="16.png" src="http://thimg.todayhumor.co.kr/upfile/201801/1515043295b43ee223b82a4ed492fa9da5ea31c026__mn271740__w959__h643__f149651__Ym201801.png" filesize="149651"></div> <div><br></div> <div><br></div> <div>각 쓰레드 끼리 읽기 위해 공유되는 리소스는 있지만 공유 자원을 업데이트 하진 않아요. 그래서 세마포어같은것도 사용하지 않았습니다.</div> <div><br></div> <div>병렬 처리 성능을 떨어뜨리는 요인이 공유 자원 말고 또 뭐가 있을까요??</div> <div><br></div> <div>자바로 만들었을 땐 스레드 수에 따라서 느려지는 일은 없었는데 C++ 정말 머리 아프네요<br 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