Re: Compact Flash performance...

Robert Hancock
2007-06-01T00:00:27Z

Jeff Garzik wrote:
> Mark Lord wrote:
>> To maximize throughput, some kind of host-queuing would be needed,
>> or just have the driver sit in a tight loop, starting the next I/O
>> immediately when the previous one finishes. Linux isn't that quick
>> (yet).
>
>
> I was talking on IRC with Tejun just recently. There are several
> controllers (and/or "situations") like this, where some amount of host
> queueing would permit greater throughput, even when NCQ is not
> supported. sata_sx4 is the most dramatic example, where host queueing
> could potentially increase speed by a factor of 10 or more, since it is
> penalized by an awful two-irq-per-command (w/ a per-host bottleneck to
> boot) setup. Silicon Image has a "command buffer". And overall, I
> designed ->qc_prep() hook separate from ->qc_issue() to enable the
> prepartion of multiple commands such that it only takes a simple "go"
> I/O to start a transaction, immediately after the previous one ends.
>
> Jeff

Theoretically NVIDIA nForce4 ADMA could likely do this as well, as it
seems to allow chaining up multiple commands to execute in succession
(assuming they're not NCQ)..

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