deswappify.pl

#!/usr/bin/perl

use strict;

sub deswappify {
    my $pid = shift;
    my $fh = undef;
    my $start_addr, $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\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`) {

  if(m/^ *(\d+) *(.{0,40})/) { 
    $pid=$1; 
    $desc=$2; 

    deswappify($pid);
  }
}

For anyone getting errors such as

Global symbol "$end_addr" requires explicit package name (did you forget to declare "my $end_addr"?) at deswappify.pl line 8.
Global symbol "$end_addr" requires explicit package name (did you forget to declare "my $end_addr"?) at deswappify.pl line 16.
Global symbol "$end_addr" requires explicit package name (did you forget to declare "my $end_addr"?) at deswappify.pl line 28.
Global symbol "$end_addr" requires explicit package name (did you forget to declare "my $end_addr"?) at deswappify.pl line 31.

I've fixed the script to work properly with strict mode :)

https://gist.github.com/Someguy123/b221986a279e1dff5f1c139562f9ca73

See https://github.com/wiedemannc/deswappify-auto for an automatic python daemon performing deswapping based on the ideas of this script.