added shm-hugepages.pl

README.md

@@ -256,7 +256,56 @@ Note that even with HugePages enabled and used, there is shared memory that is n
 This database instance was started with `use_large_pages = ONLY`, so we know that all SGA memory is in HugePages.
 
 
+## Test HugePages
 
+The script `shm-hugepages.pl` can be used to see if HugePages are working:
+
+```text
+perldoc shm-hugepages.pl
+
+shm-hugepages.pl
+     This script attempts create shared memory segments using HugePages
+
+       [oracle]$ perl shm.pl
+       waiting for input
+
+     In another session
+
+       [root@boc-solver ~]# ipcs -m
+
+       ------ Shared Memory Segments --------
+       key        shmid      owner      perms      bytes      nattch     status
+       0x00000000 4          oracle     700        4294967296 0
+
+       [root@boc-solver ~]# grep Huge /proc/meminfo
+       AnonHugePages:         0 kB
+       HugePages_Total:    2048
+       HugePages_Free:     2047
+       HugePages_Rsvd:     2047
+       HugePages_Surp:        0
+       Hugepagesize:       2048 kB
+
+     Now release the memory by pressing ENTER
+
+       [oracle]$ perl shm.pl
+       waiting for input
+       [oracle]
+   
+     Check Memory again
+
+       [root]# ipcs -m
+
+       ------ Shared Memory Segments --------
+       key        shmid      owner      perms      bytes      nattch     status
+
+       [root]# grep Huge /proc/meminfo
+       AnonHugePages:         0 kB
+       HugePages_Total:    2048
+       HugePages_Free:     2048
+       HugePages_Rsvd:        0
+       HugePages_Surp:        0
+       Hugepagesize:       2048 kB
+```
 
 
 

shm-hugepages.pl

@@ -0,0 +1,73 @@
+#!/usr/bin/env perl
+
+use warnings;
+use strict;
+#use Data::Dumper;
+
+=head1 shm-hugepages.pl
+
+ This script attempts create shared memory segments using HugePages
+
+   [oracle]$ perl shm.pl
+   waiting for input
+
+ In another session
+
+   [root@boc-solver ~]# ipcs -m
+
+   ------ Shared Memory Segments --------
+   key        shmid      owner      perms      bytes      nattch     status
+   0x00000000 4          oracle     700        4294967296 0
+
+   [root@boc-solver ~]# grep Huge /proc/meminfo
+   AnonHugePages:         0 kB
+   HugePages_Total:    2048
+   HugePages_Free:     2047
+   HugePages_Rsvd:     2047
+   HugePages_Surp:        0
+   Hugepagesize:       2048 kB
+
+ Now release the memory by pressing ENTER
+
+   [oracle]$ perl shm.pl
+   waiting for input
+   [oracle]
+   
+ Check Memory again
+
+   [root]# ipcs -m
+
+   ------ Shared Memory Segments --------
+   key        shmid      owner      perms      bytes      nattch     status
+
+   [root]# grep Huge /proc/meminfo
+   AnonHugePages:         0 kB
+   HugePages_Total:    2048
+   HugePages_Free:     2048
+   HugePages_Rsvd:        0
+   HugePages_Surp:        0
+   Hugepagesize:       2048 kB
+
+=cut
+
+my $gigs=4;
+my $shmSize = $gigs * 1024 * 2**20;
+
+use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR S_IRWXU SHM_HUGETLB S_IXUSR);
+use IPC::SharedMem;
+#my $shm = IPC::SharedMem->new(IPC_PRIVATE , 2048 * 2**20, S_IRWXU | SHM_HUGETLB);
+
+my $shm = IPC::SharedMem->new(IPC_PRIVATE , $shmSize, (S_IRUSR | S_IWUSR | S_IXUSR) | SHM_HUGETLB)
+	or die "cannot allocate shared memory\n";
+
+$shm->write(pack("S", 4711), 2, 2);
+my $data = $shm->read(0, 2);
+my $ds = $shm->stat;
+
+#print Dumper($ds);
+
+print "waiting for input\n";
+
+my $input=<>;
+
+$shm->remove;