[rdiff-backup-users] Various benchmark results

[Ben Escoto]

Here are some benchmark results I compiled for the recent version.
Below, machine A is a 233Mhz K6 w 64MB RAM, and machine B is an Athlon
XP 2000 w 512MB RAM.  Both have an IDE disk (5400 or 7200 rpm).  For
the remote test they were connected by a high latency 56k
modem/PPP/internet link.  All times are in seconds.  The directory
backed up or restored had 10000 1-byte files is in.  Skip to the end
for conclusions.

===== Local tests on machine A =====================================

Initial back up:   rdiff-backup v0.11.0:  238
                   rdiff-backup v0.11.1:  188
                   rsync -aH --delete  :  70
                   cp -a               :  77

Update, no change: rdiff-backup v0.11.0:  126
                   rdiff-backup v0.11.1:  75
                   rsync -aH --delete  :  26

All changed:       rdiff-backup v0.11.0:  742
                   rdiff-backup v0.11.1:  590
                   rsync -aH --delete  :  116

Restoring to       rdiff-backup v0.11.0:  232
empty dir:         rdiff-backup v0.11.1:  261

Restore no change: rdiff-backup v0.11.1:  62


===== Remote test machine A -> machine B ===========================

Initial back up:   rdiff-backup v0.11.0:  257
                   rdiff-backup v0.11.1:  235
                   rsync -aH --delete  :  215
                   scp -r              :  8300 (estimated)

Update no change:  rdiff-backup v0.11.0:  121
                   rdiff-backup v0.11.1:  98
                   rsync -aH --delete  :  64

All changed:       rdiff-backup v0.11.0:  443
                   rdiff-backup v0.11.1:  420
                   rsync -aH --delete  :  216

Restoring to       rdiff-backup v0.11.0:  36000 (estimated)
empty dir:         rdiff-backup v0.11.1:  181

===================================================================

Comments: Version 0.11.1 is significantly faster than 0.11.0, but I
was hoping writing the metadata out would make more of a difference.
Restores over high latency links used to be embarrassingly slow, but
are now decent (about 200x speed increase!).

I was surprised how fast rsync was doing local copies.  It was faster
than cp in my test, and about 3x faster than rdiff-backup.  However,
over the slow modem link, rdiff-backup did a little better and was
only 10-50% slower than rdiff-backup.  For the 'all changed' cases,
rdiff-backup slows down compared to rsync, and is 2 (remote case) to 5
(local) times slower.  This makes sense, since rdiff-backup must write
an increment (reverse) diff for each file, and rsync doesn't.

So my guess is that rdiff-backup will be 10%-500% slower than rsync in
most situations, assuming the system has enough memory to run rsync
(which can use a lot) without swapping.


-- 
Ben Escoto

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