void
read()
{
    TFile* file = TFile::Open("test_highmem_cluster.root");

    TTree* tree;
    file->GetObject("t", tree);

    Long_t prevRes = 0;
    Long_t prevVirt = 0;

    for (Long64_t e = 0; e < tree->GetEntries(); ++e) {
        tree->GetEntry(e);

        ProcInfo_t p;
        gSystem->GetProcInfo(&p);

        if (prevRes != p.fMemResident || prevVirt != p.fMemVirtual) {
            prevRes = p.fMemResident;
            prevVirt = p.fMemVirtual;

            std::cout << e << " " << prevRes << " " << prevVirt << std::endl;
        }
    }
}