From owner-freebsd-net Thu Sep 14 13:50:36 2000 Delivered-To: freebsd-net@freebsd.org Received: from field.videotron.net (field.videotron.net [205.151.222.108]) by hub.freebsd.org (Postfix) with ESMTP id 3E4F437B422 for ; Thu, 14 Sep 2000 13:50:30 -0700 (PDT) Received: from modemcable136.203-201-24.mtl.mc.videotron.ca ([24.201.203.136]) by field.videotron.net (Sun Internet Mail Server sims.3.5.1999.12.14.10.29.p8) with ESMTP id <0G0W00GJ49W4MA@field.videotron.net> for freebsd-net@FreeBSD.ORG; Thu, 14 Sep 2000 16:50:28 -0400 (EDT) Date: Thu, 14 Sep 2000 16:53:59 -0400 (EDT) From: Bosko Milekic Subject: RE: Clusters larger than PAGE_SIZE and contigmalloc() In-reply-to: <31269226357BD211979E00A0C9866DABE411F5@rios.sitaranetworks.com> X-Sender: bmilekic@jehovah.technokratis.com To: Charles Richmond Cc: freebsd-net@FreeBSD.ORG Message-id: MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Thu, 14 Sep 2000, Charles Richmond wrote: > So maybe I am being blind on this, but... > > It seems to me if the mbuf clusters cross page boundaries > in an unaligned fashion as the earlier suggestion of 8 X 1.5k > would do or if the size is privately configurable and thus not > guaranteed to align, then the DMA code is forced into a scatter > gather mode, even if the actual pages are contiguous. Can someone > clear up my blindness? > > Charlie I'm unsure of what the DMA code is forced to do, but there are likely alignment problems with the buffer that will cross the page boundry. Bosko Milekic bmilekic@technokratis.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message