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Latency numbers every programmer should know
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L1 cache reference 0.5 ns | |
Branch mispredict 5 ns | |
L2 cache reference 7 ns 14x L1 cache | |
Mutex lock/unlock 25 ns | |
Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
Compress 1K bytes with Zippy 3,000 ns | |
Send 1K bytes over 1 Gbps network 10,000 ns 0.01 ms | |
Read 1 MB sequentially from memory 250,000 ns 0.25 ms | |
Round trip within same datacenter 500,000 ns 0.5 ms | |
Read 1 MB sequentially from SSD 1,000,000 ns 1 ms 4X memory | |
Disk seek 10,000,000 ns 10 ms 20x datacenter roundtrip | |
Read 1 MB sequentially from disk 20,000,000 ns 20 ms 80x memory, 20X SSD | |
Send packet CA->Netherlands->CA 150,000,000 ns 150 ms | |
By Jeff Dean (http://research.google.com/people/jeff/) | |
With some updates from Brendan: http://brenocon.com/dean_perf.html | |
Comparisons from https://gist.github.com/2844130 | |
Assuming ~1GB/sec SSD | |
1 ns = 10-9 seconds | |
1 ms = 10-3 seconds |
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