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Signed-off-by: arpitkh101 <arpit5khandelwal@gmail.com>
Co-authored-by: Luka Govedič <ProExpertProg@users.noreply.github.com>
(cherry picked from commit d7284a26)

Signed-off-by: Lucas Wilkinson <lwilkins@redhat.com>
(cherry picked from commit 5cdd6645)

Signed-off-by: Isotr0py <mozf@mail2.sysu.edu.cn>
Signed-off-by: Isotr0py <2037008807@qq.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
(cherry picked from commit 0ec84221)

Signed-off-by: juliendenize <julien.denize@mistral.ai>
(cherry picked from commit 1b1e35aa)

Signed-off-by: juliendenize <julien.denize@mistral.ai>
(cherry picked from commit 5e5646e2)

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>
Signed-off-by: Nick Hill <nhill@redhat.com>
Co-authored-by: Nick Hill <nhill@redhat.com>
(cherry picked from commit 0a9caca9)

Signed-off-by: Sage Moore <sage@neuralmagic.com>
(cherry picked from commit e6f114ac)

Signed-off-by: jthomson04 <jwillthomson19@gmail.com>
(cherry picked from commit 1528e079)

Signed-off-by: bbartels <benjamin@bartels.dev>
(cherry picked from commit 2d613de9)

Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
Co-authored-by: Benjamin Chislett <bchislett@nvidia.com>
(cherry picked from commit 51c57b51)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>
(cherry picked from commit 68ffbca7)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>
(cherry picked from commit 951445a5)

Signed-off-by: Julien Denize <julien.denize@mistral.ai>
Signed-off-by: Julien Denize <40604584+juliendenize@users.noreply.github.com>
Signed-off-by: Mickael Seznec <mickael@mistral.ai>
Signed-off-by: Roger Wang <hey@rogerw.io>
Co-authored-by: Roger Wang <hey@rogerw.io>
Co-authored-by: Mickael Seznec <mickael@mistral.ai>

Signed-off-by: Tsai, Louie <louie.tsai@intel.com>
Signed-off-by: Louie Tsai <louie.tsai@intel.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Li, Jiang <bigpyj64@gmail.com>

Signed-off-by: Boyuan Feng <boyuan@meta.com>

Signed-off-by: zhyajie <yajizhan@amd.com>
Co-authored-by: zhyajie <yajizhan@amd.com>

Signed-off-by: Boyuan Feng <boyuan@meta.com>

Signed-off-by: Wushi Dong <dongws@meta.com>

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

Signed-off-by: Zhang Xiangze <Xiangze.Zhang@arm.com>

Signed-off-by: Shengqi Chen <harry-chen@outlook.com>

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

Signed-off-by: Divakar Verma <divakar.verma@amd.com>

Signed-off-by: Divakar Verma <divakar.verma@amd.com>
Co-authored-by: Cyrus Leung <tlleungac@connect.ust.hk>

Signed-off-by: Bradley <bradley.b.pitt@gmail.com>

Signed-off-by: Zuyi Zhao <zhaozuy@amazon.com>

Signed-off-by: Johnny Yang <johnnyyang@google.com>

Signed-off-by: Seiji Eicher <seiji@anyscale.com>
Co-authored-by: rongfu.leng <1275177125@qq.com>

Signed-off-by: Wei Wei <wwei6@meta.com>

Signed-off-by: Zhuohan Li <zhuohan123@gmail.com>
Signed-off-by: Nick Hill <nhill@redhat.com>
Co-authored-by: Nick Hill <nhill@redhat.com>

Signed-off-by: Andrew Xia <axia@fb.com>
Co-authored-by: Andrew Xia <axia@fb.com>

Signed-off-by: Divakar Verma <divakar.verma@amd.com>
Signed-off-by: Divakar Verma <137818590+divakar-amd@users.noreply.github.com>
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Signed-off-by: mgoin <mgoin64@gmail.com>
Co-authored-by: mgoin <mgoin64@gmail.com>

Signed-off-by: Nick Hill <nhill@redhat.com>

Signed-off-by: Alexei V. Ivanov <alexei.ivanov@amd.com>
Signed-off-by: Alexei-V-Ivanov-AMD <156011006+Alexei-V-Ivanov-AMD@users.noreply.github.com>
Co-authored-by: Kevin H. Luu <khluu000@gmail.com>

Signed-off-by: leo-pony <nengjunma@outlook.com>

Signed-off-by: Finbarr Timbers <finbarrtimbers@gmail.com>

Introduces three new Prometheus histograms for fine-grained observability of KV cache residency behavior:

vllm:kv_block_lifetime_seconds — total lifetime from allocation to free
vllm:kv_block_idle_before_evict_seconds — idle duration before eviction
vllm:kv_block_reuse_gap_seconds — time between consecutive reuses of the same block

These metrics help operators analyze KV cache efficiency, reuse patterns, and eviction timing beyond simple utilization rates.

Implementation uses monotonic timestamps for accuracy, 1% sampling for minimal overhead (~48 bytes/block), and is fully thread-safe with zero runtime cost when disabled.

Two new runtime flags are introduced:

--kv-cache-metrics – enable KV cache residency metrics
--kv-cache-metrics-sample – control sampling ratio (default: 0.01)
Signed-off-by: Shivam <shivamprasad91@gmail.com>