linux-kernel - Re: [PATCH 1/3] Make /dev/urandom scalable

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Date:	Fri, 25 Sep 2015 16:24:25 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Austin S Hemmelgarn <ahferroin7@...il.com>
Cc:	Jeff Epler <jepler@...ythonic.net>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	kirill.shutemov@...ux.intel.com, herbert@...dor.apana.org.au,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/3] Make /dev/urandom scalable

On Fri, Sep 25, 2015 at 03:07:54PM -0400, Austin S Hemmelgarn wrote:
> 
> Interestingly, based on what dieharder is already saying about performance,
> /dev/urandom is slower than AES_OFB (at least, on this particular system,
> happy to provide hardware specs if someone wants).

Yeah, not surprised by that.  We're currently using a crypto hash
instead of AES, which means we're not doing any kind of hardware
acceleration.

Crazy applications that want to spend 100% of the CPU generating
random numbers instead of you know, doing _useful_ work
notwithstanding, /dev/urandom never had high performance as one of its
design goals.  The assumption was that if you needed that kind of
performance, you would use a user-space cryptographic random number
generator.

					- Ted
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