LFQueue

Lock-free ring queue implementation inspired by DPDK rte_ring.

Focused mainly on understanding synchronization, cache coherency, batching, and compiler/codegen behavior in low-latency systems.

Current status:

• optimized SPSC paths
• experimental/tunable MPMC paths

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Queue Types

Queue	Purpose
SPSCQueue<T>	single producer single consumer
SPSCQueueBatch<T>	batched SPSC
MPMCQueue<T>	multi producer multi consumer
MPMCQueueBatch<T>	batched MPMC

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Optimizations

• cacheline separation
• power-of-two masking
• cached remote indices
• AVX2 payload copies
• batching
• reduced publication frequency
• branch prediction hints
• always_inline hot paths
• bulk enqueue/dequeue
• warmup-aware benchmarking

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Benchmarks

Benchmarks were run on physically separate cores (2 -> 4) with thread pinning enabled.

Throughput

Median throughput across 10 runs:

Payload	LFQueue	Drogalis	Rigtorp	BoostSPSC
Pointer	121.0	106.2	69.5	61.6
2B	120.6	106.7	66.6	62.0
4B	115.9	92.9	68.4	73.8
8B	110.1	91.9	76.3	58.6
16B	70.3	70.1	65.9	50.3
32B	72.6	50.5	50.8	32.7
64B	45.3	36.0	35.6	16.1

Units: M ops/sec

Latency

Measured using rdtscp ping-pong benchmarks on pinned physical cores (2 -> 4). (avg of 10 runs)

Median latency (cycles):

Payload	LFQueue	Drogalis	Rigtorp
2B	528	512	508
4B	520	501	504
8B	527	503	506
16B	525	518	516
32B	368	368	367
64B	390	388	389

Batch Throughput (for lfqueue)

Benchmark	Result
Batch Throughput	412.6 M ops/sec
Best Burst Sweep	582.3 M ops/sec
Best Publish Interval	681.2 M ops/sec

Benchmark Environment

Setting	Value
CPU	Ryzen 5
RAM	16GB
Queue Capacity	65536
Operations	50M
Compiler Flags	-O3 -march=native -mavx2 -ftree-vectorize -fno-tree-slp-vectorize -flto
Thread Pinning	enabled
Warmup	enabled

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Running

Build + run GCC benchmarks:

make run

Build + run Clang benchmarks:

make run-clang

Custom core placement:

make run PRODUCER_CORE=2 CONSUMER_CORE=4

make run-clang PRODUCER_CORE=2 CONSUMER_CORE=4

Avoid SMT sibling pairs like:

0 -> 1

Use physically separate cores instead:

2 -> 4

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Sanitizer Check

make check-sanity

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perf / Assembly

LFQueue:

make lf-run
make perf-lf
make lf-asm

Drogalis:

make dro-run
make perf-dro
make dro-asm

Rigtorp:

make rigtorp-run
make perf-rigtorp
make rigtorp-asm