Skip to content

Instantly share code, notes, and snippets.

View freepaddler's full-sized avatar

Victor Chu freepaddler

2 followers · 0 following
View GitHub Profile
@f-steff
f-steff / excel formulas.md
Last active November 25, 2025 13:12
Excel formulas to calculate IP values such as Netmask, IP range start, IP range end, Broadcast IP, Number of hosts.

Excel formulas to calculate IP values - Works in Excel and Google Sheet.

Updated 2023-12-11: Hosts calculation updated to support CIDR or 31 and 32.

Prerequisites:

  • A1 contains an IP address, such as 10.0.0.2
  • B1 contains the number of bits in the netmask (CIDR) such as 24

The below formulas then go into C1, D1 etc. to perform the various calculations. Some calculations depends on other calculations.

@jboner
jboner / latency.txt
Last active March 19, 2026 16:42
Latency Numbers Every Programmer Should Know
Latency Comparison Numbers (~2012)
----------------------------------
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 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD