On Thu, May 24, 2007 at 01:43:56PM -0500, Dave Plonka wrote: > Note however, that such a configuration couldn't even do 100K > RRD files without the patch to fadvise RANDOM to suppress readahead. > I believe any post-2.6.5 Linux has the posix_fadvise behavior that > the patch leverages. > > Also, Tobi has integrated the patch in the code he's testing.
I "only" have about 40K RRD's with 5-minute update intervals, but the machine had problems keeping up with this so I decided to try out your patches. Since we're on RRDtool 1.0.49, though, I did a back-port of your fadvise code to that version - very easy, but if anyone else wants it drop me a note and I'll put the diff up for download. The result was that the memory utilisation for the buffer cache dropped dramatically, as I'd expected. However, the general I/O activity did not go down - in fact, it increased by about 15-20%, as measured by vmstat. This is a Linux 2.6.18 (Debian 4.0) system; the RRD files are on a ReiserFS filesystem. Re-coding the application that handles the RRD updates to cache them in memory and bundle updates together turned out to be a lot more effective way of tackling the problem. We're running Hobbit, not MRTG - I have no idea if this would even be possible with MRTG. Regards, Henrik _______________________________________________ rrd-developers mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-developers
