https://forums.anandtech.com/threads/official-amd-ryzen-benchmarks-reviews-prices-and-discussion.2499879/page-128#post-38774366
현재 발생하는 문제들 중에서도 꽤나 황당한 문제인데 현재 윈도우즈는 라이젠의 16개 쓰레드 전부를 개별적인 캐시를 갖는 논리프로세서로 인식하고 있습니다.
Logical Processor to Cache Map:
*--------------- Data Cache 0, Level 1, 32 KB, Assoc 8, LineSize 64
*--------------- Instruction Cache 0, Level 1, 64 KB, Assoc 4, LineSize 64
*--------------- Unified Cache 0, Level 2, 512 KB, Assoc 8, LineSize 64
*--------------- Unified Cache 1, Level 3, 16 MB, Assoc 16, LineSize 64
-*-------------- Data Cache 1, Level 1, 32 KB, Assoc 8, LineSize 64
-*-------------- Instruction Cache 1, Level 1, 64 KB, Assoc 4, LineSize 64
-*-------------- Unified Cache 2, Level 2, 512 KB, Assoc 8, LineSize 64
-*-------------- Unified Cache 3, Level 3, 16 MB, Assoc 16, LineSize 64
--*------------- Data Cache 2, Level 1, 32 KB, Assoc 8, LineSize 64
--*------------- Instruction Cache 2, Level 1, 64 KB, Assoc 4, LineSize 64
--*------------- Unified Cache 4, Level 2, 512 KB, Assoc 8, LineSize 64
--*------------- Unified Cache 5, Level 3, 16 MB, Assoc 16, LineSize 64
---*------------ Data Cache 3, Level 1, 32 KB, Assoc 8, LineSize 64
---*------------ Instruction Cache 3, Level 1, 64 KB, Assoc 4, LineSize 64
---*------------ Unified Cache 6, Level 2, 512 KB, Assoc 8, LineSize 64
---*------------ Unified Cache 7, Level 3, 16 MB, Assoc 16, LineSize 64
----*----------- Data Cache 4, Level 1, 32 KB, Assoc 8, LineSize 64
----*----------- Instruction Cache 4, Level 1, 64 KB, Assoc 4, LineSize 64
----*----------- Unified Cache 8, Level 2, 512 KB, Assoc 8, LineSize 64
----*----------- Unified Cache 9, Level 3, 16 MB, Assoc 16, LineSize 64
-----*---------- Data Cache 5, Level 1, 32 KB, Assoc 8, LineSize 64
-----*---------- Instruction Cache 5, Level 1, 64 KB, Assoc 4, LineSize 64
-----*---------- Unified Cache 10, Level 2, 512 KB, Assoc 8, LineSize 64
-----*---------- Unified Cache 11, Level 3, 16 MB, Assoc 16, LineSize 64
------*--------- Data Cache 6, Level 1, 32 KB, Assoc 8, LineSize 64
------*--------- Instruction Cache 6, Level 1, 64 KB, Assoc 4, LineSize 64
------*--------- Unified Cache 12, Level 2, 512 KB, Assoc 8, LineSize 64
------*--------- Unified Cache 13, Level 3, 16 MB, Assoc 16, LineSize 64
-------*-------- Data Cache 7, Level 1, 32 KB, Assoc 8, LineSize 64
-------*-------- Instruction Cache 7, Level 1, 64 KB, Assoc 4, LineSize 64
-------*-------- Unified Cache 14, Level 2, 512 KB, Assoc 8, LineSize 64
-------*-------- Unified Cache 15, Level 3, 16 MB, Assoc 16, LineSize 64
--------*------- Data Cache 8, Level 1, 32 KB, Assoc 8, LineSize 64
--------*------- Instruction Cache 8, Level 1, 64 KB, Assoc 4, LineSize 64
--------*------- Unified Cache 16, Level 2, 512 KB, Assoc 8, LineSize 64
--------*------- Unified Cache 17, Level 3, 16 MB, Assoc 16, LineSize 64
---------*------ Data Cache 9, Level 1, 32 KB, Assoc 8, LineSize 64
---------*------ Instruction Cache 9, Level 1, 64 KB, Assoc 4, LineSize 64
---------*------ Unified Cache 18, Level 2, 512 KB, Assoc 8, LineSize 64
---------*------ Unified Cache 19, Level 3, 16 MB, Assoc 16, LineSize 64
----------*----- Data Cache 10, Level 1, 32 KB, Assoc 8, LineSize 64
----------*----- Instruction Cache 10, Level 1, 64 KB, Assoc 4, LineSize 64
----------*----- Unified Cache 20, Level 2, 512 KB, Assoc 8, LineSize 64
----------*----- Unified Cache 21, Level 3, 16 MB, Assoc 16, LineSize 64
-----------*---- Data Cache 11, Level 1, 32 KB, Assoc 8, LineSize 64
-----------*---- Instruction Cache 11, Level 1, 64 KB, Assoc 4, LineSize 64
-----------*---- Unified Cache 22, Level 2, 512 KB, Assoc 8, LineSize 64
-----------*---- Unified Cache 23, Level 3, 16 MB, Assoc 16, LineSize 64
------------*--- Data Cache 12, Level 1, 32 KB, Assoc 8, LineSize 64
------------*--- Instruction Cache 12, Level 1, 64 KB, Assoc 4, LineSize 64
------------*--- Unified Cache 24, Level 2, 512 KB, Assoc 8, LineSize 64
------------*--- Unified Cache 25, Level 3, 16 MB, Assoc 16, LineSize 64
-------------*-- Data Cache 13, Level 1, 32 KB, Assoc 8, LineSize 64
-------------*-- Instruction Cache 13, Level 1, 64 KB, Assoc 4, LineSize 64
-------------*-- Unified Cache 26, Level 2, 512 KB, Assoc 8, LineSize 64
-------------*-- Unified Cache 27, Level 3, 16 MB, Assoc 16, LineSize 64
--------------*- Data Cache 14, Level 1, 32 KB, Assoc 8, LineSize 64
--------------*- Instruction Cache 14, Level 1, 64 KB, Assoc 4, LineSize 64
--------------*- Unified Cache 28, Level 2, 512 KB, Assoc 8, LineSize 64
--------------*- Unified Cache 29, Level 3, 16 MB, Assoc 16, LineSize 64
---------------* Data Cache 15, Level 1, 32 KB, Assoc 8, LineSize 64
---------------* Instruction Cache 15, Level 1, 64 KB, Assoc 4, LineSize 64
---------------* Unified Cache 30, Level 2, 512 KB, Assoc 8, LineSize 64
---------------* Unified Cache 31, Level 3, 16 MB, Assoc 16, LineSize 64
본래대로면 L1 명령/데이터 캐시와 L2 캐시는 두개의 쓰레드가 공유하는 캐시로, L3 캐시는 16개의 쓰레드 전부가 공유하는 통합 캐시로 인식되어야 합니다.(왼쪽 바에서 별표 하나하나가 n번 쓰레드가 해당 캐시를 소유하고 있다는 겁니다.)
하지만 현재 라이젠은 개별 스레드가 L1 명령/데이터 캐시와 L2, L3을 전부 공유하지 않고 독자적으로 갖는 프로세서로 인식하고 있습니다. 16개의 쓰레드가 전부 독립된 논리프로세서라고 인식하는 것만 아니라 무려 16MB 짜리 L3 캐시를 코어마다 달고 있는 16 코어짜리 프로세서로 인식하고 있는겁니다.
자연히 스케쥴링 문제도 있고 이런 잘못된 정보를 받은 어플리케이션이 거기에 맞춰서 동작하면 자연히 성능저하가 발생합니다.
이게 M$의 잘못인지 AMD의 잘못인지는 모르겠습니다만 좀 많이 황당한 버그라 이런 버그가 생길수도 있구나 싶어서 놀랍습니다.
Moria
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