Date: Wed, 23 Jun 1999 19:56:18 -0400 From: Simon Shapiro <shimon@simon-shapiro.org> To: freebsd-arch@freebsd.org Subject: Intelligent I/O Opportunities Message-ID: <37717422.251ED67@simon-shapiro.org>
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Hi Y'll
When doing block (or raw) I/O to an i2o device, we can easily control
the I/O operation in this manner:
WRITE: Can be normal write, write-verify, write-through or write back.
READ: Can be normal, cached, or prefetched (with pre-fetch amount
specified).
BOTH: A command can go ``solo'' or be queued. Solo is essentially
out-of band, while normal I/O puts the command in the queue,
subject to elevator sorts, etc.
QUESTION: Is there a way to bring forward such hints into the buf
struct? If so, normal drivers can ignore these, but i2o based I/O
subsystems can benefit from improved safety, performance, or both.
Applying this to the i2o code is trivial, but I need some input.
[In case people are not aware of it, Simon is working on an I2O
subsystem for FreeBSD. -EE]
--
Sincerely Yours, Shimon@Simon-Shapiro.ORG
770.265.7340
Simon Shapiro
Unwritten code has no bugs and executes at twice the speed of mouth
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