Date: Tue, 8 Apr 2003 19:30:21 +0200 From: Alexander Leidinger <Alexander@Leidinger.net> To: Dag-Erling Smorgrav <des@ofug.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: <20030408193021.77aa8706.Alexander@Leidinger.net> In-Reply-To: <xzpof3gnc6f.fsf@flood.ping.uio.no> References: <Pine.BSF.4.21.0304081001400.27414-100000@root.org> <xzpof3gnc6f.fsf@flood.ping.uio.no>
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On Tue, 08 Apr 2003 19:15:04 +0200
Dag-Erling Smorgrav <des@ofug.org> wrote:
> 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.
I like to think about it as a buffer, not a cache. A write-cache
acknowledges the write as soon as it hits the cache (and not the
physical storage) and talking about TQ as a cache makes me feel bad...
Bye,
Alexander.
--
To boldly go where I surely don't belong.
http://www.Leidinger.net Alexander @ Leidinger.net
GPG fingerprint = C518 BC70 E67F 143F BE91 3365 79E2 9C60 B006 3FE7
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