From owner-freebsd-hackers@FreeBSD.ORG Mon May 8 22:59:53 2006 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A8F6616A4F0 for ; Mon, 8 May 2006 22:59:53 +0000 (UTC) (envelope-from bharmaji@gmail.com) Received: from nz-out-0102.google.com (nz-out-0102.google.com [64.233.162.207]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3B86543D45 for ; Mon, 8 May 2006 22:59:53 +0000 (GMT) (envelope-from bharmaji@gmail.com) Received: by nz-out-0102.google.com with SMTP id l1so1317275nzf for ; Mon, 08 May 2006 15:59:52 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type; b=KVq4lIzsYr1tw9yn/gITAi946BuooqvfNW5Qvm4tpNsYDLES9mhtUESJTE4UsTl7UTtWnC1wIHialuCKaiJEhHZn0QsFqBhW4MGIe6p1PQXmPa9Wl3FbBsUq2PbDxd41Hfqyfkz2YkjHtBsqyDusWFGH30r92rfTFKBu1gZkPXA= Received: by 10.65.252.6 with SMTP id e6mr1363546qbs; Mon, 08 May 2006 15:59:52 -0700 (PDT) Received: by 10.65.133.13 with HTTP; Mon, 8 May 2006 15:59:52 -0700 (PDT) Message-ID: <67beabb0605081559j3904ada3vb5a952cc3195ae44@mail.gmail.com> Date: Mon, 8 May 2006 15:59:52 -0700 From: "Bharma Ji" To: freebsd-hackers@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: differences between M_CACHE, M_DEVBUF, M_TEMP X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 May 2006 22:59:53 -0000 Hi I am trying to understand the difference in these three different memories. Code comments in kern_malloc.c says that M_DEVBUF should be used for device driver. I didn't however see any major difference between the three memories. Can a device theoretically take up memory from M_TEMP (or M_CACHE) segment? Similary can device drivers using M_DEVBUF also allocate from M_CACHE / M_TEMP if needed.