# core-to-core-latency **Repository Path**: MouseZhang/core-to-core-latency ## Basic Information - **Project Name**: core-to-core-latency - **Description**: No description available - **Primary Language**: Unknown - **License**: MIT - **Default Branch**: main - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2026-01-27 - **Last Updated**: 2026-01-27 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README Measuring CPU core-to-core latency ================================== ![License](https://img.shields.io/badge/license-MIT-green.svg) [![Cargo](https://img.shields.io/crates/v/core-to-core-latency.svg)](https://crates.io/crates/core-to-core-latency) [![Rust 1.57+](https://img.shields.io/badge/rust-1.57+-lightgray.svg)](https://www.rust-lang.org/tools/install) We measure the latency it takes for a CPU to send a message to another CPU via its cache coherence protocol. By pinning two threads on two different CPU cores, we can get them to do a bunch of compare-exchange operation, and measure the latency. How to run: ``` $ cargo install core-to-core-latency $ core-to-core-latency ``` Single socket results ---------------------- CPU | Median Latency -------------------------------------------------------------------------------| ------------------ AMD Ryzen 9 7950X, 16 Cores, zen4, 2022-Q3 | 68ns AMD EPYC 7773X, 64 Cores, Milan-X, 2022-Q1 | 115ns Intel Xeon Gold 6242, 16 Cores, Cascade Lake, 2019-Q2 | 48ns Intel Xeon Phi 7210, 64 Cores, Knights Landing, 2016-Q2 | 91ns HiSilicon Kunpeng 920-6426, 64 cores, ARMv8.2-A, 2019-Q1 | 72ns Intel Core i9-12900K, 8P+8E Cores, Alder Lake, 12th gen, 2021-Q4 | 35ns, 44ns, 50ns Intel Core i9-9900K, 3.60GHz, 8 Cores, Coffee Lake, 9th gen, 2018-Q4 | 21ns Intel Core i7-1165G7, 2.80GHz, 4 Cores, Tiger Lake, 11th gen, 2020-Q3 | 27ns Intel Core i7-6700K, 4.00GHz, 4 Cores, Skylake, 6th gen, 2015-Q3 | 20ns Intel Core i5-10310U, 4 Cores, Comet Lake, 10th gen, 2020-Q2 | 21ns Intel Core i5-4590, 3.30GHz 4 Cores, Haswell, 4th gen, 2014-Q2 | 21ns Apple M1 Pro, 6P+2E Cores, 2021-Q4 | 40ns, 53ns, 145ns Intel Xeon Platinum 8375C, 2.90GHz, 32 Cores, Ice Lake, 3rd gen, 2021-Q2 | 51ns Intel Xeon Platinum 8275CL, 3.00GHz, 24 Cores, Cascade Lake, 2nd gen, 2019-Q2 | 47ns Intel Xeon E5-2695 v4, 2.10GHz, 18 Cores, Broadwell, 5th gen, 2016-Q1 | 44ns AMD EPYC 7R13, 48 Cores, Milan, 3rd gen, 2021-Q1 | 23ns, 107ns AMD Ryzen Threadripper 3960X, 3.80GHz, 24 Cores, Zen 2, 3rd Gen, 2019-Q4 | 24ns, 94ns AMD Ryzen Threadripper 1950X, 3.40GHz, 16 Cores, Zen, 1st Gen, 2017-Q3 | 25ns, 154ns AMD Ryzen 9 5950X, 3.40GHz, 16 Cores, Zen3, 4th gen, 2020-Q4 | 17ns, 85ns AMD Ryzen 9 5900X, 3.40GHz, 12 Cores, Zen3, 4th gen, 2020-Q4 | 16ns, 84ns AMD Ryzen 7 5800U, 1.9GHz up to 4.4GHz, 8 Cores, Zen3, 4th gen, 2021-Q4 | 19ns AMD Ryzen 7 5700X, 3.40GHz, 8 Cores, Zen3, 4th gen, 2022-Q2 | 18ns AMD Ryzen 7 2700X, 3.70GHz, 8 Cores, Zen+, 2nd gen, 2018-Q3 | 24ns, 92ns AMD Ryzen 9 5900HX, 3.3GHz, 8 Cores, Zen3, 4th gen, 2021-Q1 | 8ns, 17ns, 18ns AWS Graviton3, 64 Cores, Arm Neoverse, 3rd gen, 2021-Q4 | 46ns AWS Graviton2, 64 Cores, Arm Neoverse, 2rd gen, 2020-Q1 | 47ns Sun/Oracle SPARC T4, 2.85GHz, 8 cores, 2011-Q3 | 98ns IBM Power7, 3.3GHz, 8 Cores, 2010-Q1 | 173ns IBM PowerPC 970, 1.8GHz, 2 Cores, 2003-Q2 | 576ns ## Intel Xeon Phi 7210, 64 Cores, Knights Landing, 2016-Q2 Data provided by [Concyclics](https://github.com/Concyclics). ![image](https://user-images.githubusercontent.com/33325023/212899823-9c9513c9-33a9-49a6-8e8a-b881811e4c2b.png) ## HiSilicon Kunpeng 920-6426, 64 cores, ARMv8.2-A, 2019-Q1 Data provided by [Concyclics](https://github.com/Concyclics). ![image](https://user-images.githubusercontent.com/33325023/212899952-fb6cee52-ba0d-4add-8896-4278d57d04db.png) ## Intel Xeon Gold 6242, 16 Cores, Cascade Lake, 2019-Q2 Data provided by [Concyclics](https://github.com/Concyclics). ![image](https://user-images.githubusercontent.com/33325023/212899588-5ca08d1a-24bf-401b-8955-5052a6244aaf.png) ## AMD Ryzen 9 7950X, 16 Cores, zen4, 2022-Q3 Data provided by [zamadatix](https://github.com/zamadatix). ![image](https://user-images.githubusercontent.com/33325023/212899457-2126ad0b-f38f-4b56-b723-05bc1bb18172.png) Data provided by [zamadatix](https://github.com/zamadatix). ## AMD EPYC 7773X, 64 Cores, Milan-X, 2022-Q1 Data provided by [SchrodingerZhu](https://github.com/SchrodingerZhu). ![image](https://user-images.githubusercontent.com/33325023/212899131-5599bdcc-e2f7-4c33-9f42-cabd34e15251.png) ## Loongson 3A5000HV, 2.5GHz, 4 Cores, 2021-Q3 Data provided by [Glavo](https://github.com/Glavo). ![image](https://user-images.githubusercontent.com/33325023/212898113-8605327a-ff34-4f57-a46a-ee488c3437c8.png) ## Intel Core i9-12900K, 8P+8E Cores, Alder Lake, 12th gen, 2021-Q4 Data provided by [bizude](https://github.com/bizude). This CPU has 8 performance cores, and 2 groups of 4 efficient cores. We see CPU=8 with fast access to all other cores. ## Intel Core i9-9900K, 3.60GHz, 8 Cores, Coffee Lake, 8th gen, 2018-Q4 Data provided by [nviennot](https://github.com/nviennot). ## Intel Core i7-1165G7, 2.80GHz, 4 Cores, Tiger Lake, 11th gen, 2020-Q3 Data provided by [Jonas Wunderlich](https://github.com/jonas-w). ## Intel Core i7-6700K, 4.00GHz, 4 Cores, Skylake, 6th gen, 2015-Q3 Data provided by [CanIGetaPR](https://github.com/CanIGetaPR). ## Intel Core i5-10310U, 4 Cores, Comet Lake, 10th gen, 2020-Q2 Data provided by [Ashley Sommer](https://github.com/ashleysommer). ## Intel Core i5-4590, 3.30GHz, 4 Cores, Haswell, 4th gen, 2014-Q2 Data provided by [Felipe Lube de Bragança](https://github.com/felubra). ## Apple M1 Pro, 6P+2E Cores, 2021-Q4 Data provided by [Aditya Sharma](https://github.com/epk). We see the two efficent cores clustered together with a latency of 53ns, then two groups of 3 performance cores, with a latency of 40ns. Cross-group communication is slow at ~145ns, which is a latency typically seen in multi-socket configurations. ## Intel Xeon Platinum 8375C, 2.90GHz 32 Cores, Ice Lake, 3rd gen, 2021-Q2 From an AWS `c6i.metal` machine. ## Intel Xeon Platinum 8275CL, 3.00GHz 24 Cores, Cascade Lake, 2nd gen, 2019-Q2 From an AWS `c5.metal` machine. ## Intel Xeon E5-2695 v4, 2.10GHz 18 Cores, Broadwell, 5th gen, 2016-Q1 From a machine provided by GTHost ## AMD EPYC 7R13, 48 Cores, Milan, 3rd gen, 2021-Q1 From an AWS `c6a.metal` machine. We can see cores arranged in 6 groups of 8 in which latency is excellent within (23ns). When data crosses groups, the latency jumps to around 110ns. Note, that the last 3 groups have a better cross-group latency than the first 3 (~90ns). ## AMD Ryzen Threadripper 3960X, 3.80GHz, 24 Cores, Zen 2, 3rd Gen, 2019-Q4 Data provided by [Mathias Siegel](https://github.com/ToolsDevler). We see the CPUs in 8 groups of 3, and better performance for CPUS in the group [13,24]. ## AMD Ryzen Threadripper 1950X, 3.40GHz, 16 Cores, Zen, 1st Gen, 2017-Q3 Data provided by [Jakub Okoński](https://github.com/farnoy) We see the CPUs in 4 groups of 4, and better performance for CPUS in the group [9,16]. ## AMD Ryzen 9 5950X, 3.40GHz 16 Cores, Zen3, 4th gen, 2020-Q1 Data provided by [John Schoenick](https://github.com/Nephyrin). We can see two groups of 8 cores with latencies of 17ns intra-group, and 85ns inter-group. ## AMD Ryzen 9 5900X, 3.40GHz, 12 Cores, Zen3, 4th gen, 2020-Q4 Data provided by [Scott Markwell](https://github.com/smarkwell). We see two groups of 6 cores with latencies of 16ns intra-group and 84ns inter-group. ## AMD Ryzen 7 5800U, 1.9GHz up to 4.4GHz, 8 Cores, Zen3, 4th gen, 2021-Q4 Data provided by [George Melikov](https://github.com/gmelikov). ## AMD Ryzen 7 5700X, 3.40GHz, 8 Cores, Zen3, 4th gen, 2022-Q2 Data provided by [Ashley Sommer](https://github.com/ashleysommer). ## AMD Ryzen 7 2700X, 3.70GHz, 8 Cores, Zen+, 2nd gen, 2018-Q3 Data provided by [David Hoppenbrouwers](https://github.com/Demindiro). We can see 2 groups of 4 cores with latencies of 24ns intra-group, and 92ns inter-group. ## AMD Ryzen 9 5900HX, 3.3GHz, 8 Cores, Zen3, 4th gen, 2021-Q1 Data provided by [r4nd0m1z3r](https://github.com/r4nd0m1z3r). ## AWS Graviton3, 64 Cores, Arm Neoverse, 3rd gen, 2021-Q4 From an AWS `c7g.16xlarge` machine. ## AWS Graviton2, 64 Cores, Arm Neoverse, 2nd gen, 2020-Q1 From an AWS `c6gd.metal` machine. ## Sun/Oracle SPARC T4, 2.85GHz, 8 cores, 2011-Q3 Data provided by [Kokoa van Houten](https://github.com/koachan). ## IBM Power7, 3.3GHz, 8 Cores, 2010-Q1 Data provided by [Kokoa van Houten](https://github.com/koachan). Dual sockets results --------------------- The following shows dual-socket configuration latency where one CPU on the first socket sends a message to another CPU on the second socket. The number in parenthesis next to the latency denotes the slowdown compared to single socket. CPU | Median Latency -------------------------------------------------------------------------------| ------------------ Intel Xeon Gold 6242, 16 Cores, Cascade Lake, 2019-Q2 | 136ns (2.8x) Intel Xeon Platinum 8375C, 2.90GHz, 32 Cores, Ice Lake, 3rd gen, 2021-Q2 | 108ns (2.1x) Intel Xeon Platinum 8275CL, 3.00GHz, 24 Cores, Cascade Lake, 2nd gen, 2019-Q2 | 134ns (2.8x) Intel Xeon E5-2695 v4, 2.10GHz, 18 Cores, Broadwell, 5th gen, 2016-Q1 | 118ns (2.7x) AMD EPYC 7R13, 48 Cores, Milan, 3rd gen, 2021-Q1 | 197ns Sun/Oracle SPARC T4, 2.85GHz, 8 cores, 2011-Q3 | 356ns (3.6x) IBM Power7, 3.3GHz, 8 Cores, 2010-Q1 | 443ns (2.5x) ## Dual Intel Xeon Gold 6242, 16 Cores, Cascade Lake, 2019-Q2 Data provided by [Concyclics](https://github.com/Concyclics). ![image](https://user-images.githubusercontent.com/33325023/212899689-4761dd65-5973-4a1a-8a39-5ebb1bf205a1.png) ## Dual Intel Xeon Platinum 8375C, 2.90GHz 32 Cores, Ice Lake, 3rd gen, 2021-Q2 From an AWS `c6i.metal` machine. ## Dual Intel Xeon Platinum 8275CL, 3.00GHz 24 Cores, Cascade Lake, 2nd gen, 2019-Q2 From an AWS `c5.metal` machine. ## Dual Intel Xeon E5-2695 v4, 2.10GHz 18 Cores, Broadwell, 5th gen, 2016-Q1 From a machine provided by GTHost ## Dual AMD EPYC 7R13, 48 Cores, Milan, 3rd gen, 2021-Q1 From an AWS `c6a.metal` machine. This one is a bit odd. The single socket test for Socket 1 shows median latencies of 107ns cross-groups, but Socket 2 shows 200ns. It's 2x slower, very odd. The other platforms don't behave this way. In fact, the socket-to-socket latencies are than the core-to-core within Socket 2. Anandtech have measured [similar results on a Dual-Socket AMD EPYC 7763 and 7742](https://www.anandtech.com/show/16529/amd-epyc-milan-review/4). **Socket 2 does not behave similarly than Socket 1, it's twice as slow**. ## Sun/Oracle SPARC T4, 2.85GHz, 8 cores, 2011-Q3 Data provided by [Kokoa van Houten](https://github.com/koachan). ## Dual IBM Power7, 3.3GHz, 8 Cores, 2010-Q1 Data provided by [Kokoa van Houten](https://github.com/koachan). Hyper-threads ------------- We measure the latency between two hyper-threads of the same core CPU | Median Latency -------------------------------------------------------------------------------| ------------------ AMD Ryzen 9 7950X, 16 Cores, zne4, 2022-Q3 | 5.3ns AMD EPYC 7773X, 64 Cores, Milan-X, 2022-Q1 | 10ns Intel Xeon Gold 6242, 16 Cores, Cascade Lake, 2019-Q2 | 7.4ns Intel Core i9-12900K, 8+8 Cores, Alder Lake, 12th gen, 2021-Q4 | 4.3ns Intel Core i9-9900K, 3.60GHz, 8 Cores, Coffee Lake, 9th gen, 2018-Q4 | 6.2ns Intel Core i7-1165G7, 2.80GHz, 4 Cores, Tiger Lake, 11th gen, 2020-Q3 | 5.9ns Intel Core i7-6700K, 4.00GHz, 4 Cores, Skylake, 6th gen, 2015-Q3 | 6.9ns Intel Core i5-10310U, 4 Cores, Comet Lake, 10th gen, 2020-Q2 | 7.3ns Intel Xeon Platinum 8375C, 2.90GHz, 32 Cores, Ice Lake, 3rd gen, 2021-Q2 | 8.1ns Intel Xeon Platinum 8275CL, 3.00GHz, 24 Cores, Cascade Lake, 2nd gen, 2019-Q2 | 7.6ns Intel Xeon E5-2695 v4, 2.10GHz, 18 Cores, Broadwell, 5th gen, 2016-Q1 | 7.6ns AMD EPYC 7R13, 48 Cores, Milan, 3rd gen, 2021-Q1 | 9.8ns AMD Ryzen Threadripper 3960X, 3.80GHz, 24 Cores, Zen 2, 3rd Gen, 2019-Q4 | 6.5ns AMD Ryzen Threadripper 1950X, 3.40GHz, 16 Cores, Zen, 1st Gen, 2017-Q3 | 10ns AMD Ryzen 9 5950X, 3.40GHz, 16 Cores, Zen3, 4th gen, 2020-Q4 | 7.8ns AMD Ryzen 9 5900X, 3.40GHz, 12 Cores, Zen3, 4th gen, 2020-Q4 | 7.6ns AMD Ryzen 7 5700X, 3.40GHz, 8 Cores, Zen3, 4th gen, 2022-Q2 | 7.8ns AMD Ryzen 7 2700X, 3.70GHz, 8 Cores, Zen+, 2nd gen, 2018-Q3 | 9.7ns Sun/Oracle SPARC T4, 2.85GHz, 8 cores, 2011-Q3 | 24ns IBM Power7, 3.3GHz, 8 Cores, 2010-Q1 | 70ns --- **The notebook [results/results.ipynb](results/results.ipynb) contains the code to generate these graphs** How to use ---------- First [install Rust](https://www.rust-lang.org/tools/install) and `gcc` on linux, then: ``` $ cargo install core-to-core-latency $ core-to-core-latency Num cores: 10 Using RDTSC to measure time: false Num round trips per samples: 1000 Num samples: 300 Showing latency=round-trip-time/2 in nanoseconds: 0 1 2 3 4 5 6 7 8 9 0 1 52±6 2 38±6 39±4 3 39±5 39±6 38±6 4 34±6 38±4 37±6 36±5 5 38±5 38±6 38±6 38±6 37±6 6 38±5 37±6 39±6 36±4 49±6 38±6 7 36±6 39±5 39±6 37±6 35±6 36±6 38±6 8 37±5 38±6 35±5 39±5 38±6 38±5 37±6 37±6 9 48±6 39±6 36±6 39±6 38±6 36±6 41±6 38±6 39±6 Min latency: 34.5ns ±6.1 cores: (4,0) Max latency: 52.1ns ±9.4 cores: (1,0) Mean latency: 38.4ns ``` Contribute ----------- Use `core-to-core-latency 5000 --csv > output.csv` to instruct the program to use 5000 iterations per sample to reduce the noise, and save the results. It can be used in the jupter notebook [results/results.ipynb](results/results.ipynb) for rendering graphs. Create a GitHub issue with the generated `output.csv` file and I'll add your results. License ------- This software is licensed under the MIT license