TTreePerfStats and performance improvements using TChains

ROOT
1

Hi all,

I recently came across the following:
root.cern.ch/drupal/content/spin … -disk-spin
which I found very interesting, since possibilities to speed up root are always very welcome.

I’d be really interested in using the TTreePerfStats also with a TChain, since this is (at least personally) more often the use case as single trees.
When my chain consists of only 1 file, the CacheSize seems to have the same effect as in the example (I get a very similar plot from the TTreePerfStats).

However as soon as the chain consists of a few files, the CacheSize doesn’t seem to have an effect anymore (see attachement, one has to Zoom in on the x-axis to get a proper picture).
How would I effectively set the CacheSize for the complete TChain?

Thanks in advance,
Sebastian
perfstats.root (22.9 KB)
TTreePerfStatsTest.c (1.8 KB)

2

The TTreePerfStats class is only implemented for the case of one file and not the case of a chain of files.
The results reported for one file should not be very different from the results on a TChain anyhow.

Rene