Bug 24151 – /dev/random is too slow on Sun Blade-100 with linux-2.4.21-sparc-r0 kernel

• Product: Gentoo Linux
• Status: VERIFIED INVALID

[Description Alexey Bazhin 2003-07-09 02:15:29 UTC]

I installed Gentoo on Sun Blade-100. I'm using linux-2.4.21-sparc-r0 kernel and
my /dev/random is too slow. For example cat /dev/urandom gives many pages in
about 5 sec, and cat /dev/random gives 1-2 symbols per minute.

Reproducible: Always
Steps to Reproduce:
cat /dev/random

Actual Results:  
only 1-2 symbols per minute

Expected Results:  
many pages in short time

[Comment 1 Christian Birchinger (RETIRED) 2003-07-09 02:31:08 UTC]

The /dev/urandom device does not deliver a perfect random stream. It guaranies
a constant output only. /dev/urandom outputs week randomness when the random pool is empty while /dev/random stops outputing anything once it has no random data left in the pool. This makes /dev/random output alot less data but with
a guaranteed quallity.

On Suns there is far less data for the random pool. On badly designed archs like x86 the random pool is always able to deliver more because it's filled by various stuff like IRQ data etc. (for some things archs with lots of overhead on I/O and ugly design like x86 are better :)

There is a controversal netdev-random patch which adds various network traffic data to the randompool. You need alot of traffic to see a visible gain of it though.

However, this random vs. urandom behaviour is the same on any arch but should
alot more on SUN than on x86. But that's not a bug and cannot be fixed.

[Comment 2 Christian Birchinger (RETIRED) 2003-07-10 02:03:49 UTC]

As explained above, this urandom vs random behavore is normal and no bug.

[Comment 3 Jason Wever (RETIRED) 2003-08-17 07:41:06 UTC]

Closing