From owner-freebsd-current Wed Mar 7 9:33:28 2001 Delivered-To: freebsd-current@freebsd.org Received: from earth.backplane.com (earth-nat-cw.backplane.com [208.161.114.67]) by hub.freebsd.org (Postfix) with ESMTP id 994A337B718; Wed, 7 Mar 2001 09:33:24 -0800 (PST) (envelope-from dillon@earth.backplane.com) Received: (from dillon@localhost) by earth.backplane.com (8.11.2/8.9.3) id f27HWou70340; Wed, 7 Mar 2001 09:32:50 -0800 (PST) (envelope-from dillon) Date: Wed, 7 Mar 2001 09:32:50 -0800 (PST) From: Matt Dillon Message-Id: <200103071732.f27HWou70340@earth.backplane.com> To: Mark Murray Cc: Bruce Evans , Maxim Sobolev , dougb@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: harvest_interrupt=YES slows down machine References: <200103071437.f27EbmR59707@gratis.grondar.za> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :> causes 7750 interrupts/sec here (on a Celeron 366 overclocked to :> 522). The random task takes 100% of the available cpu cycles. This :> slows down cpu-bound processes by a factor of about 3.5. With a block :> size of 64k instead of the default of 512, this causes only 300 :> interrupts/sec. The random task takes a measly 27% of the cpu to :> process these. It can apparently only handle about 10 interrupts/second :> with a reasonable overhead (1%). : :OK. Try tweaking the "Computational intensity factor" ;-) by dropping :the kern.random.yarrow.bins: : :# sysctl -w kern.random.yarrow.bins=2 : :And let me know how well that works. : :M :-- :Mark Murray I think it would be a much better idea to cap the number of interrupts per second the reseeder accepts. e.g. have a sysctl to set the max and default it to something reasonable, like 200. The seeder would thus only run 200 times a second even if A person were getting 7750 interrupts/sec. Frankly, once we have a good random seed it would only take about 10 interrupts a second to keep the random number generator in good shape, and possibly even less. Overkill is not necessary. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message