BrowseInterval

[angelb at bugarin.us]

> angelb at bugarin.us wrote:
> > Can anyone explain how BrowseInterval affects the time it takes a
> > client to receive the server's printer definitions; ie, Added remote
> > printer "hp001"... etc
> >
> > If I set the BrowseInterval to 15 minutes, it takes a client system 6
> > minutes after it added the last printer entry from the server for
> > 2199 printers. Now, if I set the BrowseInterval to 4hrs, it takes
> > about 36 minutes to do the same thing.
> >
> > Why is it a shorter BrowsInterval takes less time while a longer
> > BrowseInterval takes more time for the client to receive all printer
> > definitions? Shouldn't it be constant regardless of the interval?
>
> Depending on the version of CUPS you are using, the packets may or
> may not be rate-limited; the current (1.1.23) release works this
> way:
>
>      1. Given the number of printers that need to be advertised,
>         the scheduler does N=ceil(num-printers/interval-in-seconds)
>         to figure out how many printers to advertise in a 1-second
>         time period.
>
>      2. Advertise N printers each second.
>
>      3. After the interval has expired, go back to #1.
>
> The algorithm is slightly more complex that that (printer state
> changes will cause additional updates during the browse interval),
> but that is the gist of it.
>
> The longest it will take to advertise 2199 printers is 2199 seconds
> (1 printer per second, the minimum rate), or approximately 36
> minutes.  With an interval of 15 minutes (900 seconds), it will
> advertise the printers at a rate of 3 per second, which should
> complete in 733 seconds or ~12 minutes (at least with the current
> algorithm)
>
> --
>

The algorithm seems to be accurate even with the slightly earlier
version I'm running. If I use the 4-hr interval, I'm getting approx .152-printer/sec but with the ceiling, that makes it 1
printer/sec. You've already mentioned that as the minimum rate. The error_log shows 1 remote printer/sec is added.

On the same system(Sun) with the BrowseInterval set at 900, I was
getting 6-printers/sec. I can confirm that by viewing the error_log and
counting the number of printer queues added every second. Perhaps I
have better transfer rate with shorter BrowseInterval.

I'm running RH's version of CUPS:
[zab3670 at stlpr500 zab3670]$ rpm -qa|grep -i cups
cups-libs-1.1.17-13.3.22
cups-1.1.17-13.3.22

The clients are AIX and Solaris systems. All of which are running a packaged version from TWW:
# pkg-info cups
cups
  checking if v1.1.20-2 installed (TWWc1120) ... yes
    installed instances ... TWWc1120r TWWc1120d TWWc1120m


I appreciate your time and for the explanation, it helps. I now know what the BrowseInterval do, somewhat. :)

Angel