Re: W2K RAMlimits

[Robert L Krawitz <rlk@alum.mit.edu>]

   From: "dickbo" <dickbo@btopenworld.com>
   Date: Fri, 14 Jun 2002 21:59:04 +0100

   Photoshop will not allow it and neither I suspect will Adobe
   because there are many millions of users who do not or cannot
   install volume RAM.

Bear with me, since I'm not familiar with Windows, but is the issue
that there's no way to create a RAM drive in Windows, or Photoshop
will detect that and flat out refuse to use it?  If the former
(there's no RAM filesystem driver) it makes sense; it would be very
unpleasant to do with user-mode code, and Adobe's not in the
filesystem business.  If the latter -- i. e. it's possible to create a
RAM-based filesystem -- and Photoshop will refuse to use it for its
swapfile, this seems rather contrary of it.

   Mind you with a nifty hard drive it is hardly worth the bother
   anyway

I don't think I'd agree with that at all.  RAM has 10-100x more
bandwidth (the very fastest disks today top out at about 50 MB/sec;
RAM bandwidth varies with the memory architecture but these days it's
typically between 1 and 3 GB/sec on Intel platforms) and about
100,000x better latency (~100 ns for RAM, ~10 ms for disk).  Again,
I'm not familiar with how well Photoshop optimizes its use of the swap
file, but if it's not able to do I/O in close to megabyte chunks it's
going to be latency-bound (which means really disastrous slowdowns)
rather than bandwidth-bound (which is still bad, but not nearly as
bad).

-- 
Robert Krawitz <rlk@alum.mit.edu>      http://www.tiac.net/users/rlk/

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