Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756120Ab3IKRCm (ORCPT ); Wed, 11 Sep 2013 13:02:42 -0400 Received: from mail-vb0-f51.google.com ([209.85.212.51]:41316 "EHLO mail-vb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752810Ab3IKRCl (ORCPT ); Wed, 11 Sep 2013 13:02:41 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Wed, 11 Sep 2013 10:02:40 -0700 Message-ID: Subject: Re: [GIT PULL] Device tree updates for v3.12 From: Tony Luck To: Linus Torvalds Cc: Tim Bird , Grant Likely , Rob Herring , Linux Kernel Mailing List , "devicetree@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1269 Lines: 33 On Tue, Sep 10, 2013 at 1:50 PM, Linus Torvalds wrote: > Of course, maybe even the stupid add_device_randomness() is fast > enough. I just wanted to point out that it definitely isn't some > optimized thing. When I posted the patch that mixes in the whole SMBIOS table: commit d114a33387472555188f142ed8e98acdb8181c6d Author: Tony Luck Date: Fri Jul 20 13:15:20 2012 -0700 dmi: Feed DMI table to /dev/random driver I asked whether there was any size issue - as it tends to be a few kilobytes on laptops and desktops, and tens of kilobytes on servers. The answer I got back then was not to worry - digesting a few kilobytes wouldn't be a problem. I just threw in a debug message to check and saw: dmi_walk_early: added 10342 bytes in 339968 cycles So a couple of hundred microseconds for me. There are plenty of machine specific values buried in there (e.g. serial numbers for all the DIMMs) ... so this looks like a good use of this much boot time. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/