s.-ms.-us.-ns|-Ġ.5 ns - CPU L1 dCACHE reference (1st introduced in late 80-ies )ġ ns - speed-of-light (a photon) travel a 1 ft (30.5cm) distance - will stay, throughout any foreseeable future :o) | | us| reminding us what Richard FEYNMAN told us: ( Credits go to Leonardo Suriano & Karl Rupp ) 2022: Still some improvements, prediction for 2025+Ġ.001 ns light transfer in Gemmatimonas phototrophica bacteriae Single Thread Perf may grow, having direct benefits from large cache-footprints and faster and wider memory-I/O & indirect benefits from less often system forced context-switching as we can have more cores to split other threads/processes among Power can grow, yet problems with power distribution & heat dissipation will increase Transistor Count can and may grow, yet less than O(n^2~3) ( power, noise, "clock") Number of logical cores can and may grow, yet not more than O(n^2~3)įrequency has hard if not impossible to circumvent physics-based ceiling already hit The last decade has evidenced, the classical process has got close to some hurdles, that do not have an achievable physical path forward. The last about 44 years of the integrated circuit technology, the classical (non-quantum) processors evolved, literally and physically "Per Aspera ad Astra". Just for a sake of 2020's review of the predictions for 2025: Haswell i7-4770 has L1=1ns, L2=3ns, 元=10ns, RAM=67ns, BranchMisprediction=4ns)įor further understanding, I recommend the excellent presentation of modern cache architectures (June 2014) from Gerhard Wellein, Hannes Hofmann and Dietmar Fey at University Erlangen-Nürnberg.įrench speaking people may appreciate an article by SpaceFox comparing a processor with a developer both waiting for information required to continue to work. Click to each processor listed on to see the L1/L2/元/RAM/.Post The Infinite Space Between Words in based on book Systems Performance: Enterprise and the Cloud.Part 6 - More things programmers can do.Old but still an excellent deep explanation about memory hardware and software interaction. What every programmer should know about memory from Ulrich Drepper (2007).Still some improvements, prediction for 2020 16 000 ns (16µs) SSD random read (olibre's note: should be less)ĥ00 000 ns (½ms) Round trip in datacenterĢ 000 000 ns (2ms) HDD random read (seek) Values having decreased but are stabilized since 2005 1 ns L1 cache See this page presenting the memory latency decrease from 1990 to 2020.YOUR MILEAGE MAY VARY."ĮDIT: I should highlight that, as well as timing/cycle information, the above intel document addresses much more (extremely) useful details of the i7 and Xeon range of processors (from a performance point of view).Ĭost to access various memories in a pretty page THEY DEPEND ONĬORE AND UNCORE FREQUENCIES, MEMORY SPEEDS, BIOS SETTINGS, "NOTE: THESE VALUES ARE ROUGH APPROXIMATIONS. The most important is the notice under the cited table, saying: Local 元 CACHE hit, modified in another core ~75 cycles ( 40.2 - 22.5 ns ) Local 元 CACHE hit, shared line in another core ~65 cycles ( 34.8 - 19.5 ns ) Local 元 CACHE hit, line unshared ~40 cycles ( 21.4 - 12.0 ns ) Local L2 CACHE hit, ~10 cycles ( 5.3 - 3.0 ns ) Local L1 CACHE hit, ~4 cycles ( 2.1 - 1.2 ns ) The second link served the following numbers: Core i7 Xeon 5500 Series Data Source Latency (approximate) I should stress, this has what you need and more (for example, check page 22 for some timings & cycles for example).Īdditionally, this page has some details on clock cycles etc. Here is a Performance Analysis Guide for the i7 and Xeon range of processors. Numbers everyone should know 0.5 ns - CPU L1 dCACHE referenceġ ns - speed-of-light (a photon) travel a 1 ft (30.5cm) distanceħ1 ns - CPU cross-QPI/NUMA best case on XEON E5-46*ġ35 ns - CPU cross-QPI/NUMA best case on XEON E7-*Ģ02 ns - CPU cross-QPI/NUMA worst case on XEON E7-*ģ25 ns - CPU cross-QPI/NUMA worst case on XEON E5-46*ġ0,000 ns - Compress 1K bytes with Zippy PROCESSĢ0,000 ns - Send 2K bytes over 1 Gbps NETWORKĢ50,000 ns - Read 1 MB sequentially from MEMORYĥ00,000 ns - Round trip within a same DataCenterġ0,000,000 ns - Read 1 MB sequentially from NETWORKģ0,000,000 ns - Read 1 MB sequentially from DISKġ50,000,000 ns - Send a NETWORK packet CA -> Netherlands
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