Date: Thu, 25 Sep 2003 09:20:23 -0700 (PDT) From: Doug White <dwhite@gumbysoft.com> To: Brian Behlendorf <brian@hyperreal.org> Cc: stable@freebsd.org Subject: Re: tuning parameters for parallel access to umass devices? Message-ID: <20030925091757.N8717@carver.gumbysoft.com> In-Reply-To: <20030923102845.I10424@fez.hyperreal.org> References: <20030922120422.W8800@fez.hyperreal.org> <20030923091649.F86981@carver.gumbysoft.com> <20030923102845.I10424@fez.hyperreal.org>
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On Tue, 23 Sep 2003, Brian Behlendorf wrote: > > On the volume being copied to, or another volume? > > On the volume being copied to (or from) - that is, while moving a big file > to/from such a device, doing an 'ls' or other operations on that device > are delayed. Well with the copy, its consuming all the available b/w to the device. Not much we can do about that without hurting I/O performance. > > > da2: 650KB/s transfers > > > > Don't forget that this isn't much faster than a floppy disk, and flash I/O > > is pretty slow anyway. > > Granted. This is do a hard drive that can definitely handle it - mounting > the same drive (Maxtor 5000XT) over firewire works brilliantly - the > full 50MB/s transfer speed, and parallel operations are fine. I just > don't have fw everywhere. Well duh ... firewire is 400Mbit, USB is 10Mbit :-) Not likely that thi sis an easy fix. It'd involve redoing the way I/O is scheduled to a device (*_strategy). -- Doug White | FreeBSD: The Power to Serve dwhite@gumbysoft.com | www.FreeBSD.org
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