deswappify.pl

#!/usr/bin/perl

use strict;
use Fcntl qw(SEEK_SET);


sub deswappify {
    my $pid = shift;
    my $fh = undef;
    my $start_addr;
    my $end_addr;


    if(open F, "/proc/$pid/smaps") {

      while(<F>) {

        if(m/^([0-9a-f]+)-([0-9a-f]+) /si){
          $start_addr=hex($1);
          $end_addr=hex($2);
        } elsif( m/^Swap:\s*(\d+) *kB/s ){

          if ($fh == undef) {
            if (!open($fh, "< :raw :bytes", "/proc/$pid/mem")) {
              print STDERR "failed to open /proc/$pid/mem\n";
              continue;
            }

            print STDERR "Deswappifying $pid...\n";
          }

          printf STDERR "%x - %x\n", $start_addr, $end_addr;

          seek($fh, $start_addr, SEEK_SET);
          while ($start_addr < $end_addr) {
            read($fh, $_, 4096);
            $start_addr += 4096;
          }
        }
      }

      close $fh if $fh != undef;
    } else {
      print STDERR "failed to open /proc/$pid/smaps\n"
    }
}

for(`ps -e -o pid,args`) {
  my $pid;
  if(m/^ *(\d+) *(.{0,40})/) {
    $pid=$1;

    deswappify($pid);
  }
}

With a single digit it now it works for me. (At my side I had nearly a million of single 4 KB pages swapped out.)