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Date:      Sat, 20 Apr 1996 21:32:10 -0700
From:      "Justin T. Gibbs" <gibbs@freefall.freebsd.org>
To:        current
Subject:   Aic7xxx driver update in current
Message-ID:  <199604210432.VAA22374@freefall.freebsd.org>

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For those of you who don't watch the commit mailing list, I've just put
into current my changes to allow SCB paging on the aic7xxx cards.  What
does this mean for you?  It should mean better throughput in your server
class machines.  SCB paging allows up to 255 concurrent commands on the
adapters that support it which means more tagged commands active per device
and better I/O scheduling to reduce seek times.  Because the code is new
and has only been tested by two people so far, it is not enabled by
default.  You must add the option "AHC_SCBPAGING_ENABLE" to your kernel
config file.  The default behavior of the driver is to use 4 tags per
device without SCB paging and 8 with.  This may change as I get more
information from people using the driver and do more benchmarks. Tagged
queueing is no longer an option (its been tested for 1 year now) and the
QUEUE_FULL_SUPPORTED stuff has gone away too.  Please test out the new
driver and report any problems back to me.  I intend to bring this driver
into -stable soon (as it fixes some other bugs too), but I want to wait
for more people to test it in -current first.

Thanks!
--
Justin T. Gibbs
===========================================
  FreeBSD: Turning PCs into workstations
===========================================



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