possible regression?

Greg Freemyer greg.freemyer at gmail.com
Sun Jan 23 22:31:52 EST 2011

On Wed, Jan 19, 2011 at 10:36 PM, Mag Gam <magawake at gmail.com> wrote:
> Running on Redhat 5.1 if I do,
> dd bs=1024 count=1000000 if=/dev/zero of=/dev/null
> I get around 30Gb/sec
> However, when I do this with 2.6.37 I get close to 5GB/sec
> Is there anything new in the kernel?


assuming you really meant 30 GB/sec vs. 5 GB/sec and there are no
errors in your test, why do you care?

ie. There is no comm or storage device I use that can run 5 GB/sec.
In fact 1 GB/sec is pretty fast for most storage.

Or is this more a curiosity thing?

The performance loss could be /dev/zero, dd, or /dev/null.  I would
guess /dev/zero which is why I wonder what you need to track this
down.  A performance limited /dev/zero at 5 GB/sec is not a big issue
for most uses.

Greg Freemyer
Head of EDD Tape Extraction and Processing team
Litigation Triage Solutions Specialist
CNN/TruTV Aired Forensic Imaging Demo -

The Norcross Group
The Intersection of Evidence & Technology

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