MDEV-23787 mtr --rr fixes

1. rr record -h randomizes number of processors. Disable THREAD_POOL_SIZE check. 2. check for kernel.perf_event_paranoid for user-friendly error message.

Author: midenok

mysql-test/include/mtr_check.sql

@@ -35,6 +35,7 @@ BEGIN
  AND variable_name != 'INNODB_BUFFER_POOL_LOAD_AT_STARTUP'
  AND variable_name not like 'GTID%POS'
  AND variable_name != 'GTID_BINLOG_STATE'
+ AND variable_name != 'THREAD_POOL_SIZE'
  ORDER BY variable_name;
 
  -- Dump all databases, there should be none

mysql-test/mysql-test-run.pl

@@ -1820,6 +1820,16 @@ sub command_line_setup {
  $opt_shutdown_timeout= 24 * 60;
  # One day for PID file creation (this is given in seconds not minutes)
  $opt_start_timeout= 24 * 60 * 60;
+ if ($opt_rr && open(my $fh, '<', '/proc/sys/kernel/perf_event_paranoid'))
+ {
+ my $perf_event_paranoid= <$fh>;
+ close $fh;
+ chomp $perf_event_paranoid;
+ if ($perf_event_paranoid == 0)
+ {
+ mtr_error("rr requires kernel.perf_event_paranoid set to 1");
+ }
+ }
  }
 
  # --------------------------------------------------------------------------