From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 19 Jan 2001 16:45:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 19 Jan 2001 16:45:38 -0500 Received: from neon-gw.transmeta.com ([209.10.217.66]:2061 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Fri, 19 Jan 2001 16:45:21 -0500 To: linux-kernel@vger.kernel.org From: torvalds@transmeta.com (Linus Torvalds) Subject: Re: Is sendfile all that sexy? Date: 19 Jan 2001 13:45:09 -0800 Organization: Transmeta Corporation Message-ID: <94ach5$mcs$1@penguin.transmeta.com> In-Reply-To: <200101192018.XAA25263@ms2.inr.ac.ru> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <200101192018.XAA25263@ms2.inr.ac.ru>, wrote: >Hello! > >> It's about direct i/o from/to pages, > >Yes. Formally, there are no problems to send to tcp directly from io space. Actually, as long as there is no "struct page" there _are_ problems. This is why the NUMA stuff was brought up - it would require that there be a mem_map for the PCI pages.. (to do ref-counting etc). >But could someone explain me one thing. Does bus-mastering >from io really work? And if it does, is it enough fast? >At least, looking at my book on pci, I do not understand >how such transfers are able to use bursts. MRM is banned for them... It does work at least on some hardware. But no, I don't think you can depend on bursting (but I don't see why it couldn't work in theory). Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/