Improve IVF index mmap performance by cache policy

[yah01]

/kind improvement
As we tested for HSNW index, MADV_RANDOM perform the best

[codecov]

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[PwzXxm]

Please provide some results from benchmarking :)

[alexanderguzhva]

two comments

1. It is an OS-specific change and it won't work in MSVC. Is it acceptable?
2. Are there any other locations where the same optimization can be applied?
   Thanks

[alexanderguzhva]

Please provide some results from benchmarking :)

And the way of running benchmarks, please :)

[yah01]

We evaluate this with an end-to-end benchmark, the dataset is 8M rows with 128 dim vectors.
search param: nq=10, topk=10, nprobe=16

Before this PR: https://argo-workflows.zilliz.cc/workflows/qa/fouramf-85grz?tab=workflow&nodeId=fouramf-85grz-3384434876&nodePanelView=summary&sidePanel=logs:fouramf-85grz-3384434876:main
QPS=0.81, avg_latency=24759.91

After this PR: https://argo-workflows.zilliz.cc/workflows/qa/fouramf-nlhgl?tab=workflow&nodeId=fouramf-nlhgl-2020693927&sidePanel=logs:fouramf-nlhgl-2020693927:main
QPS=2.18, avg_latency=9143.93

You could start the test by argo like the links mentioned above.

NOTE: the result is based on nq=10, maybe we need a result with nq=1?

[yah01]

two comments

1. It is an OS-specific change and it won't work in MSVC. Is it acceptable?
2. Are there any other locations where the same optimization can be applied?
   Thanks

1. As I know Milvus stopped windows support, and now Knowhere can't be compiled on Windows (due to HNSW impl), is Knowhere targeting on Winodws support? @liliu-z
2. For now we supports only IVF and HNSW index with mmap, HNSW has been optimized before this, so this is all

[PwzXxm]

/approve
/lgtm

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