87 lines
2.4 KiB
Perl
87 lines
2.4 KiB
Perl
#!/usr/bin/perl
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# Usage:
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# ./chewmem.pl <MiB>
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# Description:
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# This will create a character array requiring "MiB" actual memory.
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# Summarize high-level memory usage.
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# Ideally we can demonstate creating larger and larger
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# successful memory allocations until Avail is near 0.
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# It is very likely to trigger OOM Killer or cause reset
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# if we run completely out of memory.
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use warnings;
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use strict;
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use POSIX qw(strftime);
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sub show_memusage() {
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our $count;
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$::count++; $::count %= 15;
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my $Ki = 1024.0;
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my ($MemTotal, $MemFree, $Buffers, $Cached, $CommitLimit, $Committed_AS, $Slab, $SReclaimable);
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# Process all entries of MEMINFO
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my $file = '/proc/meminfo';
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open(FILE, $file) || die "Cannot open file: $file ($!)";
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MEMINFO_LOOP: while($_ = <FILE>) {
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s/[\0\e\f\r\a]//g; chomp; # strip control characters if any
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last MEMINFO_LOOP if (/^\s*$/); # end at blank-line
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if (/\bMemTotal:\s+(\d+)\s+kB/) {
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$MemTotal = $1; next MEMINFO_LOOP;
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}
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if (/\bMemFree:\s+(\d+)\s+kB/) {
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$MemFree = $1; next MEMINFO_LOOP;
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}
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if (/\bBuffers:\s+(\d+)\s+kB/) {
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$Buffers = $1; next MEMINFO_LOOP;
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}
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if (/\bCached:\s+(\d+)\s+kB/) {
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$Cached = $1; next MEMINFO_LOOP;
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}
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if (/\bCommitLimit:\s+(\d+)\s+kB/) {
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$CommitLimit = $1; next MEMINFO_LOOP;
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}
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if (/\bCommitted_AS:\s+(\d+)\s+kB/) {
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$Committed_AS = $1; next MEMINFO_LOOP;
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}
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if (/\bSlab:\s+(\d+)\s+kB/) {
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$Slab = $1; next MEMINFO_LOOP;
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}
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if (/\bSReclaimable:\s+(\d+)\s+kB/) {
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$SReclaimable = $1; next MEMINFO_LOOP;
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}
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}
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close(FILE);
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my $Avail_MiB = ($MemFree + $Cached + $Buffers + $SReclaimable)/$Ki;
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my $Strict_MiB = ($CommitLimit - $Committed_AS)/$Ki;
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my $now = strftime "%Y-%m-%d %H:%M:%S", localtime();
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if ($::count == 1) {
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printf "%19s %6s %6s %6s %6s %6s %6s %6s %6s %6s\n",
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'yyyy-mm-dd hh:mm:ss', 'Tot', 'Free', 'Ca', 'Buf', 'Slab', 'CAS', 'CLim', 'Avail', 'Strict';
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}
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printf "%19s %6.1f %6.1f %6.1f %6.1f %6.1f %6.1f %6.1f %6.1f %6.1f\n",
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$now, $MemTotal/$Ki, $MemFree/$Ki, $Cached/$Ki, $Buffers/$Ki, $Slab/$Ki,
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$Committed_AS/$Ki, $CommitLimit/$Ki, $Avail_MiB, $Strict_MiB;
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}
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#-------------------------------------------------------------------------------
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# MAIN PROGRAM
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# Autoflush output
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select(STDERR);
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$| = 1;
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select(STDOUT); # default
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$| = 1;
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my $MiB = $ARGV[0] ||=0.0;
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my $A = "A" x (1024*1024*$MiB/2);
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print "Allocating $MiB MiB character array.\n";
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while(1) {
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sleep(1);
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show_memusage();
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}
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exit 0;
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1;
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