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--- numbers-every-programmer-should-know [February 13, 2026 at 10:50] – yanevskiv
+++ numbers-every-programmer-should-know [August 22, 2026 at 15:22] (current) – external edit 127.0.0.1
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+# Numbers every programmer should know
+**[Numbers every programmer should know](https://colin-scott.github.io/personal_website/research/interactive_latency.html)** is a reference of hardware latencies: L1 cache (1ns), memory (100ns), SSD (1ms), network (10ms). These span orders of magnitude and shape every performance decision in systems design.
+Based on Jeff Dean's seminal analysis; values evolve as technology changes.
+## Example
+Typical latency hierarchy (approximate 2020s values):
+```
+L1 cache reference:           1 ns
+L2 cache reference:           7 ns
+Main memory reference:       100 ns
+Mutex lock/unlock:           100 ns
+Compress 1K with Zippy:     3,000 ns
+Network SSD read (4K):    150,000 ns
+Disk seek:             10,000,000 ns
+Network RTT CA↔NL:    150,000,000 ns
+```