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WGH-/deswappify.pl

Created October 20, 2017 00:12
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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);
}
}
@Someguy123
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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

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

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