linux-kernel - Re: [PATCH,RFC] random: collect cpu randomness

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140203033548.GC9499@logfs.org>
Date:	Sun, 2 Feb 2014 22:35:48 -0500
From:	Jörn Engel <joern@...fs.org>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Stephan Mueller <smueller@...onox.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linux Kernel Developers List <linux-kernel@...r.kernel.org>,
	macro@...ux-mips.org, ralf@...ux-mips.org, dave.taht@...il.com,
	blogic@...nwrt.org, andrewmcgr@...il.com, geert@...ux-m68k.org,
	tg@...bsd.de
Subject: Re: [PATCH,RFC] random: collect cpu randomness

On Sun, 2 February 2014 20:39:22 -0500, Theodore Ts'o wrote:
> 
> The real question is how much overhead does it add, and is it worth
> it.  Jörn, I take it that was the reason for creating an even faster,
> but weaker mixing function?  Was the existing "fast mix" causing a
> measurable overhead, or was this your just being really paranoid about
> not adding anything to the various kernel fastpaths?

It was paranoia.  And I am still somewhat paranoid and don't trust my
benchmark results yet.  Maybe on an 1024-CPU Altix with a 100k-thread
workload the overhead is too much.  Just because I couldn't measure a
difference on my wimpy notebook does not mean much.

Jörn

--
One of the painful things about our time is that those who feel certainty
are stupid, and those with any imagination and understanding are filled
with doubt and indecision.
-- Bertrand Russell
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/