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From: Julian Elischer <julian@elischer.org>
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To: Scott Long <scottl@samsco.org>
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Cc: Attilio Rao <attilio@freebsd.org>, arch@freebsd.org
Subject: Re: sglist(9)
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Scott Long wrote:

> I think this is fundamentally wrong.  You're proposing exchanging a 
> cheap operation of splitting VA's with an expensive operation of 
> allocating, splitting, copying, and refcounting sglists.  Splitting is 
> an excessively common operation, and your proposal will impact 
> performance as storage becomes exponentially faster.
> 

 From the perspective of a flashdrive driver the more
efficient the better. The current generation of devices are
doing 800MB/sec (6.4Gb/sec) of scattter-gather random IO
and really that will only go up. We are doing over 130,000 independent
transactions per second and we can put multiple drives in a single
machine.

These numbers will only increase with future developments.