perf(filemeta): phase-1~3 rename_data metadata optimization (#3011)

* chore(perf): harden amd64 profiling benchmark flow

* fix(profiling): isolate bench buckets and map protobuf conflict

* perf: avoid blocking owned local writes

* style: format profile admin handler

* docs: clarify observability trace validation

* perf: reduce mkdir overhead on local writes

* perf: add rename_data meta microbenchmark

* perf(filemeta): fast-path data_dir decode in version meta

* perf(filemeta): collapse data-dir lookup into one scan

* perf(filemeta): reduce scan allocs and refresh meta bench

* perf(ecstore): skip mkdir path on read-only open

* perf(filemeta): single-pass unshared data-dir scan

* perf(filemeta): add two-key inline remove fast path

* perf(filemeta): compare remove-two keys by bytes first

* bench(ecstore): add remove_two-only micro benchmark

* bench(ecstore): stabilize rename_data meta benchmark timing

* bench(ecstore): align rename_data path with remove_two

* perf(filemeta): avoid uuid string alloc in remove_two

* perf(filemeta): add fast-path for empty inline data

* perf(filemeta): streamline add_version match branch

* perf(filemeta): fast-return remove_key on miss

* perf(filemeta): speed up add_version insertion lookup

* style(ecstore): normalize formatting in perf-tuning files

* refactor(filemeta): unify inline data removal paths

.docker/observability/README.md

@@ -90,6 +90,54 @@ docker compose down -v
 - **Grafana**: Dashboards and datasources are provisioned from the `grafana/` directory.
 - **Collector**: Edit `otel-collector-config.yaml` to modify pipelines, processors, or exporters.
 
+### Verifying RustFS Traces
+
+When RustFS points `RUSTFS_OBS_ENDPOINT` at this stack, treat the value as the
+OTLP/HTTP base URL, for example:
+
+```bash
+export RUSTFS_OBS_ENDPOINT=http://host.docker.internal:4318
+```
+
+RustFS automatically expands that base URL to:
+
+- `/v1/traces`
+- `/v1/metrics`
+- `/v1/logs`
+
+Important behavior notes:
+
+- Logs and metrics usually appear during startup, so seeing those two signals
+  first is expected.
+- Visible trace data usually requires real HTTP/S3/gRPC request traffic after
+  startup, because request-path spans are created on demand.
+- `RUSTFS_OBS_LOGGER_LEVEL=info` keeps the top-level request span but filters
+  many nested `debug` spans. If Tempo or Jaeger looks sparse, retry with
+  `RUSTFS_OBS_LOGGER_LEVEL=debug` before suspecting collector or Tempo issues.
+
+Minimal validation flow:
+
+```bash
+# 1. Start this observability stack.
+docker compose up -d
+
+# 2. Start RustFS with OTLP/HTTP export and richer span visibility.
+export RUSTFS_OBS_ENDPOINT=http://host.docker.internal:4318
+export RUSTFS_OBS_LOGGER_LEVEL=debug
+
+# 3. Generate real request traffic.
+curl -I http://127.0.0.1:9000/health
+curl -I http://127.0.0.1:9000/health/ready
+
+# 4. Inspect Grafana or Jaeger.
+# Grafana: http://localhost:3000
+# Jaeger:  http://localhost:16686
+```
+
+If logs and metrics are present but traces are sparse, the most common cause is
+"no real request traffic yet" or "`info` level filtered nested spans", not an
+OTLP routing failure.
+
 ## Troubleshooting
 
 - **Service Health**: Check the health of services using `docker compose ps`.

.docker/observability/README_ZH.md

@@ -90,6 +90,50 @@ docker compose down -v
 -   **Grafana**: 仪表盘和数据源从 `grafana/` 目录预置。
 -   **Collector**: 编辑 `otel-collector-config.yaml` 以修改管道、处理器或导出器。
 
+### 验证 RustFS Trace
+
+当 RustFS 将 `RUSTFS_OBS_ENDPOINT` 指向这套技术栈时，应将该值视为
+OTLP/HTTP 的基础 URL，例如：
+
+```bash
+export RUSTFS_OBS_ENDPOINT=http://host.docker.internal:4318
+```
+
+RustFS 会自动在该基础 URL 后补全：
+
+- `/v1/traces`
+- `/v1/metrics`
+- `/v1/logs`
+
+需要注意：
+
+- 启动阶段通常会先看到日志和指标，因此“先有日志/指标、后有 trace”是正常现象。
+- 可见的 trace 数据通常依赖启动后的真实 HTTP/S3/gRPC 请求流量，因为请求路径上的 span 是按需创建的。
+- `RUSTFS_OBS_LOGGER_LEVEL=info` 会保留顶层请求 span，但会过滤掉很多 `debug` 级别的嵌套 span。
+  如果 Tempo 或 Jaeger 中的 trace 看起来很稀疏，建议先改成 `RUSTFS_OBS_LOGGER_LEVEL=debug`，再判断是否是 collector 或 Tempo 问题。
+
+最小验证流程：
+
+```bash
+# 1. 启动本目录下的可观测性技术栈。
+docker compose up -d
+
+# 2. 以 OTLP/HTTP 导出方式启动 RustFS，并提高 span 可见性。
+export RUSTFS_OBS_ENDPOINT=http://host.docker.internal:4318
+export RUSTFS_OBS_LOGGER_LEVEL=debug
+
+# 3. 产生真实请求流量。
+curl -I http://127.0.0.1:9000/health
+curl -I http://127.0.0.1:9000/health/ready
+
+# 4. 到 Grafana 或 Jaeger 中检查。
+# Grafana: http://localhost:3000
+# Jaeger:  http://localhost:16686
+```
+
+如果日志和指标已经正常，但 trace 仍然稀疏，最常见的原因通常是
+“还没有真实请求流量”或“`info` 级别过滤了嵌套 span”，而不是 OTLP 路由失败。
+
 ## 故障排除
 
 -   **服务健康**: 使用 `docker compose ps` 检查服务健康状况。