Date: Tue, 20 Jul 2004 15:19:59 +0100 From: Mark Murray <markm@FreeBSD.ORG> To: Robert Watson <rwatson@FreeBSD.ORG> Cc: freebsd-current@FreeBSD.ORG Subject: Re: I/O or Threading Suffer Message-ID: <200407201419.i6KEJxJX079041@grimreaper.grondar.org> In-Reply-To: Your message of "Tue, 20 Jul 2004 09:32:08 EDT." <Pine.NEB.3.96L.1040720093036.86342D-100000@fledge.watson.org>
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Robert Watson writes: > On Tue, 20 Jul 2004, Scott Long wrote: > > > If you are dd'ing from /dev/random, then you are depleting the entropy > > pool. Anything else that tries to get random numbers is going to block > > in strange ways. Trying just dd'ing from /dev/zero and see if that > > makes a difference. > > With Yarrow, /dev/random should just keep on chugging, so this is unlikely > to be the source. However, lots of /dev/random I/O may take a while to > yield if it's working hard in kernel, so if that is combined with a > scheduling nit of some sort, we could be looking at a starvation issue. When you read /dev/random, you only exercise the output generator, and this is a pretty simple piece of code. Yarrow's kernel thread is used ONLY for the entropy harvesting, and is only indirectly coupled to the output generator. M -- Mark Murray iumop ap!sdn w,I idlaH
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