From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262643AbULPI0d (ORCPT ); Thu, 16 Dec 2004 03:26:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262646AbULPI0c (ORCPT ); Thu, 16 Dec 2004 03:26:32 -0500 Received: from faui3es.informatik.uni-erlangen.de ([131.188.33.16]:3036 "EHLO faui3es.informatik.uni-erlangen.de") by vger.kernel.org with ESMTP id S262643AbULPIZ7 (ORCPT ); Thu, 16 Dec 2004 03:25:59 -0500 Date: Thu, 16 Dec 2004 09:25:50 +0100 From: Martin Waitz To: tony osborne Cc: linux-kernel@vger.kernel.org Subject: Re: OS I/O operations concepts Message-ID: <20041216082550.GL31835@admingilde.org> Mail-Followup-To: tony osborne , linux-kernel@vger.kernel.org References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="7l042bGvurpep9Wg" Content-Disposition: inline In-Reply-To: X-Habeas-SWE-1: winter into spring X-Habeas-SWE-2: brightly anticipated X-Habeas-SWE-3: like Habeas SWE (tm) X-Habeas-SWE-4: Copyright 2002 Habeas (tm) X-Habeas-SWE-5: Sender Warranted Email (SWE) (tm). The sender of this X-Habeas-SWE-6: email in exchange for a license for this Habeas X-Habeas-SWE-7: warrant mark warrants that this is a Habeas Compliant X-Habeas-SWE-8: Message (HCM) and not spam. Please report use of this X-Habeas-SWE-9: mark in spam to . X-PGP-Fingerprint: B21B 5755 9684 5489 7577 001A 8FF1 1AC5 DFE8 0FB2 User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --7l042bGvurpep9Wg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable hoi :) On Wed, Dec 15, 2004 at 09:10:03PM +0000, tony osborne wrote: > What about the disk bitmap and the one loaded into the memory. Will this = be=20 > updated at each Byte write operation? This will slow down extremely the= =20 > system speed. no, all data is first written into the buffer cache and will be written to disk later. > Should the programmer force the second option (by using BufferOutputStrea= m=20 > as in java) or is it done automatically by the JVM or OS? Writing single bytes can be slow because of another reason: system calls are expensive and it makes sense to buffer data in the application and send it to the operating system in one big system call. > Does the I/O controller (once the device driver installed) full privilege= s=20 > as the main CPU when on kernel mode? I'm not sure if i understood your question correctly but yes, The IO Controller has full access to physical memory through DMA. > is Java system.in.read (system.out.println) synchronous or asynchronous I= /O=20 > Op They are synchronous. Otherwise you couldn't access your data at the moment read() returns. --=20 Martin Waitz --7l042bGvurpep9Wg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQFBwUaNj/Eaxd/oD7IRAshUAJ9E2wgWuZ5gjP8P9z5p8wjPLLTvaACcDgmw iKJSsr4EUjucph/SDV/5wMs= =F3oG -----END PGP SIGNATURE----- --7l042bGvurpep9Wg--