Preamble
Looks like speeds to main memory are getting faster….
Main article from StackOverflow has a lot more detail.
Core i7 Xeon 5500 Series
Core i7 Xeon 5500 Series Data Source Latency (approximate) [Pg. 22]
local L1 CACHE hit, ~4 cycles ( 2.1 – 1.2 ns )
local L2 CACHE hit, ~10 cycles ( 5.3 – 3.0 ns )
local L3 CACHE hit, line unshared ~40 cycles ( 21.4 – 12.0 ns )
local L3 CACHE hit, shared line in another core ~65 cycles ( 34.8 – 19.5 ns )
local L3 CACHE hit, modified in another core ~75 cycles ( 40.2 – 22.5 ns )
remote L3 CACHE (Ref: Fig.1 [Pg. 5]) ~100-300 cycles ( 160.7 – 30.0 ns )
local DRAM ~60 ns
remote DRAM ~100 ns
General
0.5 ns - CPU L1 dCACHE reference
1 ns - speed-of-light (a photon) travel a 1 ft (30.5cm) distance
5 ns - CPU L1 iCACHE Branch mispredict
7 ns - CPU L2 CACHE reference
71 ns - CPU cross-QPI/NUMA best case on XEON E5-46*
100 ns - MUTEX lock/unlock
100 ns - own DDR MEMORY reference
135 ns - CPU cross-QPI/NUMA best case on XEON E7-*
202 ns - CPU cross-QPI/NUMA worst case on XEON E7-*
325 ns - CPU cross-QPI/NUMA worst case on XEON E5-46*
10,000 ns - Compress 1K bytes with Zippy PROCESS
20,000 ns - Send 2K bytes over 1 Gbps NETWORK
250,000 ns - Read 1 MB sequentially from MEMORY
500,000 ns - Round trip within a same DataCenter
10,000,000 ns - DISK seek
10,000,000 ns - Read 1 MB sequentially from NETWORK
30,000,000 ns - Read 1 MB sequentially from DISK
150,000,000 ns - Send a NETWORK packet CA -> Netherlands
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Source
https://gist.github.com/jboner/2841832