refactor: 문서 개선 중

2026-09-21 14:30:55 +09:00
parent c93cdea150
commit 805a18f486
1497 changed files with 525837 additions and 59152 deletions
@@ -0,0 +1,27 @@
+# Host memory pressure가 storage와 OOM으로 갈라지는 경로
+
+## Alternative text
+
+Host memory pressure가 reclaim에서 clean page 재읽기, anonymous page의 Host swap과 storage contention, 메모리 확보 실패에 따른 Host OOM으로 갈라지는 흐름도. QEMU가 OOM victim이 될 때 VM 전체가 중단될 수 있다는 결과는 본문에서 설명한다.
+
+## Long description
+
+왼쪽에서 Host memory pressure가 reclaim으로 들어간다. reclaim 이후 clean file-backed page는 버렸다가 필요할 때 storage에서 다시 읽는 경로, anonymous page는 Host swap I/O를 통해 physical storage와 경쟁하는 경로, 필요한 메모리를 확보하지 못하면 Host OOM으로 가는 경로로 갈린다. storage contention이 application latency로 이어지는 결과와 Host OOM이 QEMU를 victim으로 고를 때 VM 전체가 중단될 수 있다는 결과는 본문에서 이어 설명한다.
+
+## Elements and evidence
+
+- **Host memory pressure** (resource): 실제 Host RAM 수요가 available physical memory에 접근한 상태. Evidence: L2818–L2831.
+- **Reclaim** (component): Linux가 회수 가능한 page/cache를 처리하는 첫 대응. Evidence: L2818–L2831.
+- **clean file-backed page** (data): 원본이 storage에 있어 RAM에서 제거하고 나중에 다시 읽을 수 있다. Evidence: L2834–L2848.
+- **Host swap I/O** (storage): anonymous page의 backing이 필요할 때 host swap I/O가 생길 수 있다. Evidence: L2850–L2852, L2856–L2886.
+- **Storage contention** (storage): 여러 I/O가 한 physical device에 몰려 contention을 만든다. Evidence: L2938–L2965.
+- **Host OOM** (result): reclaim 등으로도 필요한 memory 확보에 실패했을 때 Host kernel에서 발생할 수 있다. Evidence: L3213–L3231, L3249–L3265.
+
+## Relationships
+
+- **clean file-backed page → Storage contention:** reread. Evidence: L2834–L2848.
+- **Host memory pressure → Reclaim:** pressure. Evidence: L2818–L2831.
+- **Reclaim → clean file-backed page:** file-backed. Evidence: L2834–L2848.
+- **Reclaim → Host OOM:** 확보 실패. Evidence: L3213–L3231.
+- **Reclaim → Host swap I/O:** anonymous. Evidence: L2850–L2852.
+- **Host swap I/O → Storage contention:** swap. Evidence: L2871–L2886, L2940–L2946.
@@ -0,0 +1,27 @@
+# Host memory pressure가 storage와 OOM으로 갈라지는 경로
+# Question: Host memory pressure가 생겼을 때 reclaim 이후 어떤 경로가 swap I/O와 storage contention으로 이어지고, 확보 실패는 어디서 OOM으로 이어지는가
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+n2 -> n4: "reread"
+n1 -> n3: "anonymous"
+n3 -> n4: "swap"
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+%% Host memory pressure가 storage와 OOM으로 갈라지는 경로
+%% question: Host memory pressure가 생겼을 때 reclaim 이후 어떤 경로가 swap I/O와 storage contention으로 이어지고, 확보 실패는 어디서 OOM으로 이어지는가
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+    n1["Reclaim"]
+    n2["clean file-backed page"]
+    n3[("Host swap I/O")]
+    n4[("Storage contention")]
+    n5["Host OOM"]
+    n0 -->|"pressure"| n1
+    n1 -->|"file-backed"| n2
+    n2 -->|"reread"| n4
+    n1 -->|"anonymous"| n3
+    n3 -->|"swap"| n4
+    n1 -->|"확보 실패"| n5
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+<title id="diagram-title">Host memory pressure가 storage와 OOM으로 갈라지는 경로</title>
+<desc id="diagram-description">왼쪽에서 Host memory pressure가 reclaim으로 들어간다. reclaim 이후 clean file-backed page는 버렸다가 필요할 때 storage에서 다시 읽는 경로, anonymous page는 Host swap I/O를 통해 physical storage와 경쟁하는 경로, 필요한 메모리를 확보하지 못하면 Host OOM으로 가는 경로로 갈린다. storage contention이 application latency로 이어지는 결과와 Host OOM이 QEMU를 victim으로 고를 때 VM 전체가 중단될 수 있다는 결과는 본문에서 이어 설명한다.</desc>
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