From owner-freebsd-hackers Wed Jun 26 2:48:48 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from falcon.mail.pas.earthlink.net (falcon.mail.pas.earthlink.net [207.217.120.74]) by hub.freebsd.org (Postfix) with ESMTP id 340D537B407 for ; Wed, 26 Jun 2002 02:48:39 -0700 (PDT) Received: from pool0122.cvx22-bradley.dialup.earthlink.net ([209.179.198.122] helo=mindspring.com) by falcon.mail.pas.earthlink.net with esmtp (Exim 3.33 #2) id 17N9P8-0000sy-00; Wed, 26 Jun 2002 02:48:02 -0700 Message-ID: <3D198D71.86779927@mindspring.com> Date: Wed, 26 Jun 2002 02:46:25 -0700 From: Terry Lambert X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Matthew Dillon Cc: Peter Wemm , Alfred Perlstein , Patrick Thomas , freebsd-hackers@FreeBSD.ORG Subject: Re: tunings for many httpds... References: <20020625222632.B7C7D3811@overcee.wemm.org> <3D1970E7.697D4A49@mindspring.com> <200206260758.g5Q7wPgZ019100@apollo.backplane.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Matthew Dillon wrote: > Hmm. I'm fairly sure that Linux does not quite do it that way. I > believe the 2-level page tables are copy-on-write, but that only > gives you shareability across a fork() and then only for a little > while. I'm fairly certain that Linux cannot share page tables > for post-fork modifications (like when you mmap() or get a SysV > shared segment). The rmap patches are roughly equivalent to our > i386 pmap code and allow Rik to implement page queues and proper page > aging. I wasn't saying that they were shared on the mmap(); Peter had suggested it for FreeBSD. Also "a little while" is relative; as long as you don't write the page, it should stay shared. That basically means that all instances of apache share mappings on the code pages. Here's the article I was reading in one window while typing in the other. It's linked off the article reference I posted to -arch earlier: http://old.lwn.net/2002/0124/kernel.php3 "What Rik van Riel is up to." FWIW: In the original Article: http://lwn.net/Articles/3327/ they say they've gon to a 3 level page table scheme for the Hammer port. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message