Date: Mon, 22 Sep 2003 12:08:55 -0700 (PDT) From: Brian Behlendorf <brian@hyperreal.org> To: stable@freebsd.org Subject: tuning parameters for parallel access to umass devices? Message-ID: <20030922120422.W8800@fez.hyperreal.org>
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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
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