[cups.general] Details of compression=gzip

[Michael Sweet]

On Aug 15, 2011, at 1:53 PM, Steve Bergman wrote:
> We do a lot of printing over WAN/VPN links. I have a CUPS 1.3.9 server that queues jobs to a CUPS 1.4.8 server, which then sends the jobs to local printers at that location using a combination of lpd: and socket:. I've put compression=gzip in as an argument to ipp: for all the remote printers. Setting LogLevel to debug2, I can see that for most print jobs, I get a line in the log that reports that it compressed the file to xx% of its original size. But for some jobs, I don't get that line. To be clear, even for a single printer, some jobs report the compression statistic and some don't. Does CUPS just not compress files that aren't very compressible? Am I getting all the compression that I can?

You should get a log entry for every file that gets compressed, and we don't do anything special to omit files that are already compressed, for example, we just copy and compress the file(s) in the job and use the compressed version, even if it would be larger...

> Also, is there a way to get compression statistics without setting LogLevel to debug?

Not without changing the backend source code (backend/ipp.c) and recompiling.

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Michael Sweet, Senior Printing System Engineer, PWG Chair