Para detalhar o uso de memória shmem
(e mais), você tem o comando ipcs
.
De homem ipcs
NAME ipcs - show information on IPC facilities
SYNOPSIS ipcs [options]
DESCRIPTION ipcs shows information on the inter-process communication facilities for which the calling process has read access. By default it shows information about all three resources: shared memory segments, message queues, and semaphore arrays.
Por exemplo, estou executando aqui em um servidor Apache:
$ipcs
------ Message Queues --------
key msqid owner perms used-bytes messages
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0xf4123d98 20643870 root 600 3294 12
0xfb123d9b 20676639 root 600 1242 12
0x0a123d9d 20709408 root 600 3294 12
0x91123da0 20742177 root 600 1242 12
0x75123da2 20774946 root 600 3294 12
0xbc123da5 20807715 root 600 1242 12
0x3d123da7 20840484 root 600 3294 12
0x84123daa 20873253 root 600 1242 12
0x47123dac 20906022 root 600 3294 12
0x0e123daf 20938791 root 600 1242 12
0xa6123db1 20971560 root 600 3294 12
0x2d123db4 21004329 root 600 1242 12
0x77123db6 21037098 root 600 3294 12
0x3e123db9 21069867 root 600 1242 12
0x80123dbb 21102636 root 600 3294 12
0x87123dbe 21135405 root 600 1242 12
0xa4123dc0 21168174 root 600 3294 12
0xab123dc3 21200943 root 600 1242 12
0xfd123dc5 21233712 root 600 3294 12
0x44123dc8 21266481 root 600 1242 12
0x96123dca 21299250 root 600 3294 12
0x1d123dcd 21332019 root 600 1242 12
0xa4123dcf 21364788 root 600 3294 12
0xab123dd2 21397557 root 600 1242 12
0x7a123dd4 21430326 root 600 3294 12
0x01123dd7 21463095 root 600 1242 12
0xd9123dd9 21495864 root 600 3294 12
0x20123ddc 21528633 root 600 1242 12
0x86123dde 21561402 root 600 3294 12
0x0d123de1 21594171 root 600 1242 12
------ Semaphore Arrays --------
key semid owner perms nsems
0x00000000 425984 www-data 600 1
0x00000000 1441793 www-data 600 1
0x00000000 1474562 www-data 600 1