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Low-Latency Checklist Audit

Status legend:

Status	Meaning
SHIPPED	Code + test and/or runnable example in this repo
OPTIONAL	Built when dependency is installed (auto-detect)
DOC	Documented with operator guidance; limited runtime API
PARTIAL	Touched via demo or third-party lib only
GAP	Not implemented here (reference / future module)

Industry map: 07-industry-libraries.md ·
Tutorials: ../tutorials/.

1. Hardware & OS tuning

Item	Status	Evidence
CPU isolation (`isolcpus`, `nohz_full`)	DOC	`01-hardware-os.md`
Thread pinning	SHIPPED / macOS QoS DOC	`ll/affinity.hpp`
hwloc topology	OPTIONAL	`[industry][hwloc]`
libnuma bind / alloc_onnode	SHIPPED API + Linux OPTIONAL link	`ll/linux_numa.hpp`, `[roadmap][numa]`, Linux CI
C-states / P-states / governor	DOC	`01-hardware-os.md`
Hugepages / TLB	DOC	`01-hardware-os.md`, kernel-bypass lab

2. Kernel bypass & network ingress

Item	Status	Evidence
IPollModeRx contract + stub	SHIPPED	`ll/kernel_bypass.hpp`, `[industry][bypass]`
DPDK	OPTIONAL detect + lab runbook	`STACK_WITH_DPDK`; stub when absent
OpenOnload / EF_VI	OPTIONAL detect + lab runbook	`STACK_WITH_ONLOAD`
liburing	SHIPPED API + Linux OPTIONAL	`ll/linux_uring.hpp`, Linux CI
Real Logic SBE codegen	SHIPPED	`schemas/sbe-*.xml`, `generated/sbe/`, `ll/sbe_codec.hpp`
SBE-style POD teaching aid	SHIPPED	`ll/sbe_style.hpp`
FlatBuffers	OPTIONAL	`schemas/tick.fbs`
struct_pack	SHIPPED	yalantinglibs + `ll/struct_pack_tick.hpp`
Asio / Beast / gRPC / simdjson	SHIPPED	library mesh

3. Memory architecture & cache locality

Item	Status	Evidence
Arena / object pool	SHIPPED	`ll/arena.hpp`
std::pmr	SHIPPED	`ll/pmr_arena.hpp`
mimalloc off-path	OPTIONAL	industry tests
jemalloc off-path	OPTIONAL	`ll/jemalloc_util.hpp`
False sharing / cache lines	SHIPPED	`ll/cache_line.hpp`, SPSC

4. Concurrency & lock-free

Item	Status	Evidence
`ll::SpscQueue`	SHIPPED	tests + examples
Boost.Lockfree / moodycamel	SHIPPED / OPTIONAL	industry suite
folly::ProducerConsumerQueue	OPTIONAL	auto if Folly present; `make folly`
Memory order tutorial	SHIPPED	`examples/memory_order`

5. Compiler & language

Item	Status	Evidence
C++26 project	SHIPPED	CMake
CRTP / likely	SHIPPED	`ll/branch.hpp`
LTO/PGO guidance	DOC	`05-compiler.md`

6. Benchmarking & telemetry

Item	Status	Evidence
TSC / steady_ns	SHIPPED	`ll/tsc_clock.hpp`
Portable HDR histogram	SHIPPED	`ll/HdrLatencyHistogram`
HdrHistogram_c	SHIPPED (FetchContent)	`ll/hdr_c.hpp`, `[roadmap][hdr_c]`
Google Benchmark	OPTIONAL	`bench_queues`

Focus summary

Rank	Layer	Why
1	§4 + §3	Queues, arenas, pmr
2	Library mesh + industry optional	Asio… + hwloc/FB/mimalloc/moodycamel
3	§6 Telemetry	Portable HDR + HdrHistogram_c
4	§2 Serde + §1 NUMA	SBE codegen, numa/uring APIs
5	§2 Bypass drivers	Contract + lab; DPDK/Onload not linked

Roadmap status (this release)

#	Item	Status
1	Real Logic SBE codegen	DONE — schema, generator script, committed headers, tests, tutorial
2	Linux numa + uring + CI	DONE — APIs, tests, `linux-roadmap` CI job
3	HdrHistogram_c wrapper	DONE — FetchContent + `ll::HdrHistogramC`
4	DPDK / Onload lab	DONE as contract+stub+runbook (driver GAP by design)

This audit is the checklist for PRs: new work should move a row from DOC/GAP → SHIPPED/OPTIONAL with tests.