jerrykan

#!/usr/bin/env python3

BACKUP_FILE = 'backup.ab'

# Constants
# ref: https://github.com/omnirom/android_bootable_recovery/blob/android-7.1/adbbu/twadbstream.h
TWRP = b'TWRP' + b'\x00\x00\x00\x00'

TWSTREAMHDR = b'twstreamheader'
TWFN = b'twfilename'

Artefact2

Considerations

• Tests were run in single-user mode, one at a time.
• Data was read from and written to tmpfs.
• borg-1.1rc2 seems about 10% slower than borg-1.0.11 (many possible reasons, borg-1.1rc2 binary comes from GitHub but 1.0.11 from the Arch repos)
• Still making sense of the auto,X,Y compression modes

milkey-mouse

Moved

This script has been moved to a full GitHub repository: milkey-mouse/backup-vm

hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs