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Date:      Fri, 6 Aug 2004 13:35:38 +0200
From:      "Daniel Eriksson" <daniel_k_eriksson@telia.com>
To:        <freebsd-current@freebsd.org>
Subject:   Simple BDE disc encryption benchmark
Message-ID:  <!~!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAA0VcX9IoJqUaXPS8MjT1PdsKAAAAQAAAApKSdNgL8EkaHhtB/cG3DrwEAAAAA@telia.com>

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Hi! I just ran a very simple benchmark on the GBDE disc encryption in
CURRENT. The benchmark setup looked like this:

* Slow machine (Celeron 366, 128MB mem)
* 5-CURRENT from yesterday, running off of some old ATA disc
* 2 x 9GB 10k rpm SCSI discs hooked up to an Adaptec 2940

The benchmark was to copy the /usr directory (copied from the ATA disc,
1.7GB) or a directory containing big files (/bigfiles, 1.7GB in 16 files
created by 'dd if=3D/dev/random ...') from scsi disc 1 to scsi disc 2. I =
ran
each benchmark twice and took a simple average of the results.

unencrypted to unencrypted:
/usr     :  697 real        10.6 user       235 sys  (~50% idle)
/bigfiles:  123 real         0.4 user        84 sys  (~25% idle)

unencrypted to encrypted:
/usr     : 1778 real        10.7 user       236 sys  (~35% idle)
/bigfiles:  379 real         0.4 user        82 sys  (~10% idle)

encrypted to encrypted:
/usr     : 1978 real        11.6 user       242 sys  (~25% idle)
/bigfiles:  615 real         0.4 user        80 sys  (0% idle)

The only time the CPU was completely busy was when copying /bigfiles =
from
encrypted to encrypted.

My question is: Why does the it take so much longer when encryption is
involved even though 'top' seems to think there are CPU cycles left to =
burn?

/Daniel Eriksson




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