[cups.general] RIPCache for improved performance

[Michael Sweet]

Paul Ortman wrote:
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> Simple question: For a print server that potentially serves out lots of
> lots of fairly large jobs, is fiddling with the RIPCache size in
> cupsd.conf useful.  Generally I'd assume raising it from its 8m default
> would improve performance of the rasterization of certain jobs, but I
> thought I'd ask before doing something stupid.  A bit of explanation
> about the RIPCache option (beyond the sysadmin manual) would be greatly
> appreciated.
> 
> Incidently: I'm using CUPS version 1.1.23 on a dedicated print server
> where almost all jobs come from Adobe PS drivers on windows boxes (via
> Samba) or (as PDFs?) from Mac OSX (mostly Tiger) boxes.

RIPCache will only affect jobs that are printed via pstoraster or
imagetoraster on Linux (MacOS X has their own CoreGraphics versions
of those filters, but I don't know if they respect the RIPCache
setting or not...)

Anyways, if you are printing to a non-PostScript printer using a
CUPS-based driver (Foomatic drivers don't count, they bypass the
CUPS filter system), then tuning RIPCache may improve performance.

As for the right value to use for B&W printers, multiple the width
of the page in inches by the printer resolution.  For color printers,
multiple that by 3 or 4:

     mono-cache = page-width-inches * horizontal-dpi * vertical-dpi
     color-cache = 4 * page-width-inches * horizontal-dpi * vertical-dpi

Those formulas compute the size needed to cache a 1" high strip
of raster data, which is usually optimal given current printers
and processors.

For a 600 DPI print to an HP DeskJet printer, you'd be looking at:

     4 * 8.5 * 600 * 600 = 12240000

or about 12MB for the cache size.  Epson printers need at least
twice that value, and I use values up to 512MB on some of our
test systems when printing to large format plotters...

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______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Document Software          http://www.easysw.com