And to make your intention slightly more obvious you can label the loop:

READ_TILL_TOTAL:
  while (my $line = <$fh>) {
    chomp($line);
    last READ_TILL_TOTAL if ($line =~ /TOTAL COMMAND SUMMARY/);
    my ($uid, $login, $cpupr, $cpunpr, @data) = (split("\t",$line));
  }
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This is especially helpful if you've got other loops around this block, for example a loop that opens a list of files and reads them all in turn.