From owner-freebsd-hackers Wed Mar 21 11:33:52 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from earth.backplane.com (earth.backplane.com [208.161.114.65]) by hub.freebsd.org (Postfix) with ESMTP id AA1DC37B7FA; Wed, 21 Mar 2001 11:33:29 -0800 (PST) (envelope-from dillon@earth.backplane.com) Received: (from dillon@localhost) by earth.backplane.com (8.11.2/8.9.3) id f2LJ7cp17933; Wed, 21 Mar 2001 11:07:38 -0800 (PST) (envelope-from dillon) Date: Wed, 21 Mar 2001 11:07:38 -0800 (PST) From: Matt Dillon Message-Id: <200103211907.f2LJ7cp17933@earth.backplane.com> To: Alfred Perlstein Cc: "Michael C . Wu" , Rik van Riel , Peter Wemm , izero@ms26.hinet.net, cross@math.psu.edu, grog@FreeBSD.ORG, fs@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: tuning a VERY heavily (30.0) loaded s cerver References: <200103211114.f2LBE0h57371@mobile.wemm.org> <20010321120620.A932@peorth.iteration.net> <200103211817.f2LIHR416007@earth.backplane.com> <20010321102836.N12319@fw.wintelcom.net> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Hey, talking about large amounts of swap, did you know that: : 4.2-STABLE FreeBSD 4.2-STABLE #1: Sat Feb 10 01:26:41 PST 2001 :has a max swap limit that's possibly 'low': : : b: 15912412 0 swap # (Cyl. 0 - 990*) : c: 17912412 0 unused 0 0 # (Cyl. 0 - 1114*) : :If I made b == c, then i couldn't swapon it. : :Don't ask why I have that much swap, I just needed a bunch on a dedicated :disk. :) : :-- :-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] You would have to reconfigure your kernel to reduce NSWAP from 4 to either 2 or 1. Bitmap overhead for swap is 2 bits per page (4K) of swap. There is a maximum of 2G / 16 / NSWAPDEV blocks (512 byte chunks) of swap. If NSWAPDEV is 4, this comes to: 2G/16/4x512 = 17GB. So you would be able to create approximately four 17GB swap partitions. If you reduce NSWAP to 2 you would be able to create approximately two 34GB swap partitions. If you reduce NSWAP to 1 you would be able to create approximately one 68GB swap partition. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message