From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 7 May 2001 17:48:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 7 May 2001 17:48:16 -0400 Received: from colorfullife.com ([216.156.138.34]:17683 "EHLO colorfullife.com") by vger.kernel.org with ESMTP id ; Mon, 7 May 2001 17:48:11 -0400 Message-ID: <3AF71818.F58139C6@colorfullife.com> Date: Mon, 07 May 2001 23:48:08 +0200 From: Manfred Spraul X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.4 i686) X-Accept-Language: en, de MIME-Version: 1.0 To: Alan Cox CC: Ben LaHaise , linux-kernel@vger.kernel.org Subject: Re: [PATCH] zero^H^H^H^Hsingle copy pipe In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Alan Cox wrote: > > > The main problem is that map_user_kiobuf() locks pages into memory. > > It's a bad idea for pipes. Either we must severely limit the maximum > > You only have to map them for the actual copy. The current map_user_kiobuf() doesn't have an 'mm' parameter, I can only use it from the context of the writer. I could use map_user_kiobuf_mm(), but the kiobuf structure is far too large, I really don't want a huge structure (> 8 kB?) for a simple 4 kB single copy transfer. Including a memset(,0,sizeof(*iobuf) in kiobuf_init(). I think reusing the ptrace interface (access_process_vm()) is the better solution. -- Manfred