From owner-freebsd-stable@FreeBSD.ORG  Mon Sep 22 12:08:57 2003
Return-Path: <owner-freebsd-stable@FreeBSD.ORG>
Delivered-To: freebsd-stable@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id C610D16A4B3
	for <stable@freebsd.org>; Mon, 22 Sep 2003 12:08:57 -0700 (PDT)
Received: from hyperreal.org (taz3.hyperreal.org [209.237.226.90])
	by mx1.FreeBSD.org (Postfix) with SMTP id 2BDA143FF9
	for <stable@freebsd.org>; Mon, 22 Sep 2003 12:08:57 -0700 (PDT)
	(envelope-from brian@hyperreal.org)
Received: (qmail 96328 invoked from network); 22 Sep 2003 19:08:58 -0000
Received: from localhost.hyperreal.org (HELO fez.hyperreal.org) (127.0.0.1)
  by localhost.hyperreal.org with SMTP; 22 Sep 2003 19:08:58 -0000
Received: (qmail 8906 invoked by uid 1000); 22 Sep 2003 19:08:55 -0000
Received: from localhost (sendmail-bs@127.0.0.1)
  by localhost with SMTP; 22 Sep 2003 19:08:55 -0000
Date: Mon, 22 Sep 2003 12:08:55 -0700 (PDT)
From: Brian Behlendorf <brian@hyperreal.org>
To: stable@freebsd.org
Message-ID: <20030922120422.W8800@fez.hyperreal.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-Spam-Rating: localhost.hyperreal.org 1.6.2 0/1000/N
Subject: tuning parameters for parallel access to umass devices?
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Production branch of FreeBSD source code
	<freebsd-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
	<mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
	<mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 22 Sep 2003 19:08:57 -0000


It looks like copying files over USB to a umass device causes other I/O
attempts to be blocked for an unreasonable (10-20 seconds) amount of time.
Here's the device in question:

da2 at umass-sim0 bus 0 target 0 lun 0
da2: <Maxtor 5000XT v01.00.00 0100> Fixed Direct Access SCSI-0 device
da2: 650KB/s transfers
da2: 239371MB (490232832 512 byte sectors: 64H 32S/T 42763C)

Though I've seen it with other umass devices, like my digital camera and
the Archos jukebox.

While copying a large file (or large number of files), and in parallel
attempting to do a "ls" of a directory or read a file, one waits a
significant amount of time.  Is there a way to tune the disk, mount
options, kernel sysctls, something, to make file I/O over USB less
blocking?

	Brian