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Re: dm-crypt/LUKS performance



David Fuchs wrote:
> In short, the write speed plummets to around 160 MB/s, as opposed to 270
> MB/s on the naked partition; read speed is at 115 MB/s (slower than writing
> - no idea why), as opposed to 465 MB/s on the bare partition. (I've pasted
> the results below.)

I don't have an immediate answer but I do have a comment.  You are
comparing raw partition I/O of /dev/sdd6 and talking about encryption
but I think you are actually using encryption + lvm.  Is lvm in there?
You didn't quite describe your configuration fully.  What is your
/dev/mapper/test attached to?  

If lvm then it would be a useful data point to compare an lvm only
benchmark as well.  Then you would see how much of a hit is imposed by
each of encryption and lvm separately.  It is possible that your hit
is only due to lvm.

And if you are not using encryption + lvm then that is another
suggestion.  I normally use encryption with lvm.  

When I previously benchmarked this on a ThinkPad T42 laptop way back
in the day I didn't get anywhere near the performance hit you are
reporting now.  I was using encryption + lvm.  Of course then the top
end high speed was only a fraction of your bottom end slow speed so
maybe times have simply changed.

Bob

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