From owner-freebsd-stable Sat Jan 13 14: 6:11 2001 Delivered-To: freebsd-stable@freebsd.org Received: from earth.backplane.com (placeholder-dcat-1076843399.broadbandoffice.net [64.47.83.135]) by hub.freebsd.org (Postfix) with ESMTP id DD4C937B402 for ; Sat, 13 Jan 2001 14:05:53 -0800 (PST) Received: (from dillon@localhost) by earth.backplane.com (8.11.1/8.9.3) id f0DM5pJ35749; Sat, 13 Jan 2001 14:05:51 -0800 (PST) (envelope-from dillon) Date: Sat, 13 Jan 2001 14:05:51 -0800 (PST) From: Matt Dillon Message-Id: <200101132205.f0DM5pJ35749@earth.backplane.com> To: Bruce Burden Cc: freebsd-stable@FreeBSD.ORG Subject: Re: /swap too large? What?? References: <20010113002643.A33278@tigerfish2.my.domain> <200101131927.f0DJRSS34276@earth.backplane.com> <20010113150956.B37497@tigerfish2.my.domain> Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG : Hi Matt, :> :> The only thing that can cause this is if you have configured an :> absurdly large NSWAPDEV. :> : Well, I had NSWAPDEV set for 20 (why? I don't know!) but : according to my calculations, that should still allow a 3.4GB : swap, or 2x what I have. : : I have dropped things back to NSWAPDEV=3, and see if that : does anything. : : Bruce That will fix it. Generally speaking the amount of bitmap space the kernel must allocate scales with (largest swap partition) * NSWAPDEV. An NSWAPDEV of 4 (the default) is reasonable for most swap configurations. But if you have NSWAPDEV of 20 and are only using one or two swap devices (and one of them is a gig), then the kernel winds up having to reserve bitmap space for (1 gig) x 20 blocks, which wastes a huge amount of kernel memory unnecessarily. This is all in the name of making interleaved swap work. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message