linux-kernel - Re: [PATCH] /dev/random: Insufficient of entropy on many architectures

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Message-ID: <20130910211009.GI29237@thunk.org>
Date:	Tue, 10 Sep 2013 17:10:09 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	John Stultz <john.stultz@...aro.org>
Cc:	Stephan Mueller <smueller@...onox.de>,
	LKML <linux-kernel@...r.kernel.org>, dave.taht@...ferbloat.net
Subject: Re: [PATCH] /dev/random: Insufficient of entropy on many
 architectures

On Tue, Sep 10, 2013 at 01:46:21PM -0700, John Stultz wrote:
> 
> We do read the clocksource fairly frequently though, so rather then
> re-reading on each interrupt, could you instead re-use the points at
> interrupt time where we already read the clocksource, like in
> hrtimer_interrupt()?

How often is that time updated?  Is there some documentation whree I
can understand how this works?  I confess to be pretty ignorant about
the details of how our time keeping systems work inside Linux.

Same question for sched_clock(); what are its guarantees, both in
terms of granularity and cost of overhead.  Is there any comprehensive
documentation that I should be reading?

Thanks,

						- Ted
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