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Date:      Tue, 08 Apr 2003 19:15:04 +0200
From:      Dag-Erling Smorgrav <des@ofug.org>
To:        Nate Lawson <nate@root.org>
Cc:        sos@freebsd.org
Subject:   Re: cvs commit: src/sys/dev/ata ata-all.c ata-all.h ata-chipset.cata-dma.c ata-pci.c ata-pci.h
Message-ID:  <xzpof3gnc6f.fsf@flood.ping.uio.no>
In-Reply-To: <Pine.BSF.4.21.0304081001400.27414-100000@root.org> (Nate Lawson's message of "Tue, 8 Apr 2003 10:09:20 -0700 (PDT)")
References:  <Pine.BSF.4.21.0304081001400.27414-100000@root.org>

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Nate Lawson <nate@root.org> writes:
> Tagged queuing is orthogonal to caching.  TQ allows multiple transactions
> to be passed to the drive, allowing it to order and aggregate the requests
> as it thinks best.  TQ can be done with no cache because all the drive is
> tracking is handles to transactions (typically 16 bit ids).  Think of it
> as more like a pipeline than a cache.

It can't be done without cache, because you can't queue and reorder
transactions without some sort of cache.

DES
-- 
Dag-Erling Smorgrav - des@ofug.org



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