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Date:      Tue, 12 Nov 2002 12:06:06 -0600 (CST)
From:      Chris Dillon <cdillon@wolves.k12.mo.us>
To:        Dan Ellard <ellard@eecs.harvard.edu>
Cc:        freebsd-fs@FreeBSD.ORG, <freebsd-hackers@FreeBSD.ORG>
Subject:   Re: how to control tagged queueing?
Message-ID:  <20021112120159.Y41695-100000@duey.wolves.k12.mo.us>
In-Reply-To: <Pine.BSF.4.44.0211121104530.60100-100000@bowser.eecs.harvard.edu>

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On Tue, 12 Nov 2002, Dan Ellard wrote:

> I'm experimenting with the effects of SCSI tagged queueing on file
> system performance.  Is there any kind of global toggle somewhere in
> the kernel to turn tagged queueing on and off, and/or knob to limit
> the number of outstanding tags?  Tagged queue management all seems
> to be done at the device level, and I haven't found hooks for
> controlling it at a higher level (but I thought I'd ask before
> running off to write something).
>
> I'm running 4.6.2p4, in case things have changed.  (If there's a
> nicer interface in 4.7, I'll install it immediately!)

man camcontrol

Specifically:

camcontrol tags [device id] [generic args] [-N tags] [-q] [-v]
camcontrol negotiate [device id] [generic args] [-T enable|disable]

--
 Chris Dillon - cdillon(at)wolves.k12.mo.us
 FreeBSD: The fastest and most stable server OS on the planet
 - Available for IA32 (Intel x86) and Alpha architectures
 - IA64, PowerPC, UltraSPARC, ARM, and S/390 under development
 - http://www.freebsd.org

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