Skip to main content

Rockchip Linux Memory Debugging Common Commands

ID: RK-KF-YF-140

Release Version: V1.0.0

Date: 2021-01-06

Security Level: □Top Secret □Secret □Internal ■Public

DISCLAIMER

This document is provided "as is". Rockchip Electronics Co., Ltd. ("the Company") makes no express or implied representations or warranties regarding the accuracy, reliability, completeness, merchantability, fitness for a particular purpose, or non-infringement of any statements, information, or content in this document. This document is for reference as a usage guide only.

Due to product version upgrades or other reasons, this document may be updated or modified from time to time without any notice.

Trademark Statement

"Rockchip", "Rockchip", "Rockchip" are registered trademarks of the Company and belong to the Company.

All other registered trademarks or trademarks mentioned in this document are owned by their respective owners.

Copyright © 2021 Rockchip Electronics Co., Ltd.

Beyond the scope of fair use, without the written permission of the Company, no individual or entity may extract, copy, or distribute part or all of the content of this document in any form.

Rockchip Electronics Co., Ltd.

Address: No. 18, Area A, Software Park, Tongpan Road, Fuzhou, Fujian Province

Website: www.rock-chips.com

Customer Service Tel: +86-4007-700-590

Customer Service Fax: +86-591-83951833

Customer Service Email: fae@rock-chips.com

Preface

Overview

This document introduces common commands related to memory during Linux development, including viewing total memory size, usage, and reserved memory size.

Product Versions

Chip NameKernel Version
ARM series chips4.19

Intended Audience

This document (guide) is mainly applicable to the following engineers:

Technical Support Engineers

Software Development Engineers

Revision History

VersionAuthorDateDescription
V1.0.0Xu Jianqun2021-01-06Initial version

Table of Contents

[TOC]

Total Memory Info​

meminfo​

  • cat /proc/meminfo

    MemTotal:        1497696 kB
    MemFree:          590524 kB
    MemAvailable:     773252 kB
    Buffers:             768 kB
    Cached:           216892 kB
    SwapCached:        14204 kB
    Active:           260884 kB
    Inactive:         176744 kB
    Active(anon):     120620 kB
    Inactive(anon):   106688 kB
    Active(file):     140264 kB
    Inactive(file):    70056 kB
    Unevictable:        3224 kB
    Mlocked:            3224 kB
    SwapTotal:        748844 kB
    SwapFree:         346156 kB
    Dirty:               776 kB
    Writeback:             0 kB
    AnonPages:        220804 kB
    Mapped:           194276 kB
    Shmem:              4968 kB
    KReclaimable:      43900 kB
    Slab:             111060 kB
    SReclaimable:      40648 kB
    SUnreclaim:        70412 kB
    KernelStack:       18496 kB
    PageTables:        42096 kB
    NFS_Unstable:          0 kB
    Bounce:                0 kB
    WritebackTmp:          0 kB
    CommitLimit:     1497692 kB
    Committed_AS:   41751048 kB
    VmallocTotal:   263061440 kB
    VmallocUsed:       30368 kB
    VmallocChunk:          0 kB
    Percpu:             2528 kB
    CmaTotal:         532480 kB
    CmaFree:               0 kB

MemTotal = MemFree + Buffers + Cached

Swap: SwapTotal/SwapFree, enabled and allocated by system scripts using the swap command

Swap partitions are special hard disk space. When actual memory is insufficient, the operating system takes temporarily unused data from memory and places it in the swap partition, freeing up enough memory space for currently running programs.

Slab: Current Slab usage size, including reclaimable SReclaimable and unreclaimable SUnreclaim. If it grows too large, there may be a memory leak.

Vmalloc: VmallocTotal is the total size, VmallocUsed is the used size.

Cma: CmaTotal is the total size, CmaFree is the free size.

When CMA is borrowed by the system, it is also considered used, and CmaFree decreases.

sysrq-trigger​

  • echo m > /proc/sysrq-trigger

    Mem-Info:
    active_anon:43194 inactive_anon:26284 isolated_anon:0
     active_file:35286 inactive_file:17959 isolated_file:0
     unevictable:806 dirty:0 writeback:0 unstable:0
     slab_reclaimable:10164 slab_unreclaimable:17630
     mapped:48836 shmem:1280 pagetables:10550 bounce:0
     free:134653 free_pcp:717 free_cma:0
    Node 0 active_anon:172776kB inactive_anon:105136kB active_file:141144kB inactive_file:71836kB unevictable:3224kB isolated(anon):0kB isolated(file):0kB mapped:195344kB dirty:0kB writeback:0kB shmeo
    DMA32 free:538612kB min:4884kB low:24024kB high:25520kB active_anon:172776kB inactive_anon:105136kB active_file:141144kB inactive_file:71836kB unevictable:3224kB writepending:0kB present:2095104kB
    lowmem_reserve[]: 0 0 0
    DMA32: 13625*4kB (UEH) 12210*8kB (UEH) 8286*16kB (UMEH) 4151*32kB (UMEH) 1157*64kB (UMEH) 223*128kB (UM) 46*256kB (U) 9*512kB (U) 2*1024kB (U) 0*2048kB 0*4096kB = 538612kB
    58687 total pagecache pages
    3564 pages in swap cache
    Swap cache stats: add 155134, delete 151579, find 11930/52536
    Free swap  = 346412kB
    Total swap = 748844kB
    523776 pages RAM
    0 pages HighMem/MovableOnly
    149352 pages reserved
    133120 pages cma reserved

Kernel Memory Info​

slab​

Kernel memory debugging interface. Compiling requires enabling two macros:

CONFIG_SLUB_SYSFS=y
CONFIG_SLUB_DEBUG=y

Command to view total slab size:

echo `cat /proc/slabinfo |awk 'BEGIN{sum=0;}{sum=sum+$3*$4;}END{print sum/1024/1024}'` MB

kernfs_node_cache​

The following command shows kernfs uses 2.5M, 655 pages = 2.55859375 MBytes

[root@RV1126_RV1109:/]# cat /proc/slabinfo |grep kernfs_node_cache
kernfs_node_cache  18319  18340    144   28    1 : tunables    0    0    0 : slabdata    655    655      0

Code location: fs/kernfs/mount.c

void __init kernfs_init(void)
{

	/*
	 * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
	 * can access the slab lock free. This could introduce stale nodes,
	 * please see how kernfs_find_and_get_node_by_ino filters out stale
	 * nodes.
	 */
	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
					      sizeof(struct kernfs_node),
					      0,
					      SLAB_PANIC | SLAB_TYPESAFE_BY_RCU,
					      NULL);
}

inode_cache​

The following command shows inode cache uses 3.2M, 816 pages = 3.1875 MBytes

[root@RV1126_RV1109:/]# cat /proc/slabinfo |grep inode_cache
inode_cache         6282   6340    408   20    2 : tunables    0    0    0 : slabdata    317    317      0

Code location: fs/inode.c

void __init inode_init(void)
{
	/* inode slab cache */
	inode_cachep = kmem_cache_create("inode_cache",
					 sizeof(struct inode),
					 0,
					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
					 init_once);
}

memblock​

System reserved memory debugging interface. Compiling requires adding memblock=debug to bootargs.

chosen {
	bootargs = "earlycon=uart8250,mmio32,0xff570000 console=ttyFIQ0 memblock=debug";
};
[    0.000000] MEMBLOCK configuration:
[    0.000000]  memory size = 0x3fdb8000 reserved size = 0x11706eb8
[    0.000000]  memory.cnt  = 0x2
[    0.000000]  memory[0x0]     [0x00000000-0x083fffff], 0x08400000 bytes flags: 0x0
[    0.000000]  memory[0x1]     [0x08648000-0x3fffffff], 0x379b8000 bytes flags: 0x0
[    0.000000]  reserved.cnt  = 0x7
[    0.000000]  reserved[0x0]   [0x00004000-0x00007fff], 0x00004000 bytes flags: 0x0
[    0.000000]  reserved[0x1]   [0x00100000-0x00e32b2f], 0x00d32b30 bytes flags: 0x0
[    0.000000]  reserved[0x2]   [0x08000000-0x080fffff], 0x00100000 bytes flags: 0x0
[    0.000000]  reserved[0x3]   [0x08300000-0x08318fff], 0x00019000 bytes flags: 0x0
[    0.000000]  reserved[0x4]   [0x2dc00000-0x3dbfffff], 0x10000000 bytes flags: 0x0 CMA
[    0.000000]  reserved[0x5]   [0x3df00000-0x3dfb7387], 0x000b7388 bytes flags: 0x0
[    0.000000]  reserved[0x6]   [0x3f800000-0x3fffffff], 0x00800000 bytes flags: 0x0 CMA

Among them, the larger reserved areas include initrd (used for loading rootfs) and node memmap (used for page memory management).

initrd reserved 13 MBytes

void __init arm_memblock_init(const struct machine_desc *mdesc)
{
	arm_initrd_init();
}

node memmap reserved 8 MBytes

[    0.000000] On node 0 totalpages: 262006
[    0.000000] memblock_reserve: [0x3ef75000-0x3f774fff] memblock_virt_alloc_internal+0x108/0x1a4
[    0.000000] alloc_node_mem_map: node 0, pgdat b0d4bd00, node_mem_map eef75000
[    0.000000]   Normal zone: 2048 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 262006 pages, LIFO batch:63

Device memory info printed at boot:

[    0.000000] Virtual kernel memory layout:
[    0.000000]     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
[    0.000000]     fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
[    0.000000]     vmalloc : 0xf0800000 - 0xff800000   ( 240 MB)
[    0.000000]     lowmem  : 0xb0000000 - 0xf0000000   (1024 MB)
[    0.000000]     pkmap   : 0xafe00000 - 0xb0000000   (   2 MB)
[    0.000000]     modules : 0xaf000000 - 0xafe00000   (  14 MB)
[    0.000000]       .text : 0x(ptrval) - 0x(ptrval)   (9184 kB)
[    0.000000]       .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
[    0.000000]       .data : 0x(ptrval) - 0x(ptrval)   ( 332 kB)
[    0.000000]        .bss : 0x(ptrval) - 0x(ptrval)   ( 896 kB)
[    0.000000] Memory: 752320K/1048024K available (8192K kernel code, 331K rwdata, 1900K rodata, 1024K init, 895K bss, 25368K reserved, 270336K cma-reserved, 0K highmem)

752320K: Available free page memory, nr_free_pages() << (PAGE_SHIFT - 10)

1048024K: Total visible physical memory, physpages << (PAGE_SHIFT - 10)

kernel code: Kernel code, codesize = _etext - _stext

rwdata: Read-write data segment, datasize = _edata - _sdata

rodata: Read-only data segment, rosize = __end_rodata - __start_rodata

init: Includes init_data_size = __init_end - __init_begin and init_code_size = _einittext - _sinittext

bss: Memory area for uninitialized global variables, bss_size = __bss_stop - __bss_start

reserved: Memory reserved by memblock, physpages - totalram_pages - totalcma_pages

cma-reserved: CMA reserved memory, totalcma_pages

[    0.000000] Reserved memory: created CMA memory pool at 0x3f800000, size 8 MiB
[    0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[    0.000000] Reserved memory: created CMA memory pool at 0x2dc00000, size 256 MiB
[    0.000000] OF: reserved mem: initialized node isp, compatible id shared-dma-pool

memory​

The kernel's memory supports multiple blocks. On Rockchip platforms, before entering the kernel, some memory is used for special purposes, such as OPTEE/ATF code which needs to be placed in the 132M~135M range. The 0x248000 size memory block below is used for OPTEE code storage.

[root@RV1126_RV1109:/]# cat /sys/kernel/debug/memblock/memory
   0: 0x00000000..0x083fffff
   1: 0x08648000..0x3fffffff

reserved​

[root@RV1126_RV1109:/]# cat /sys/kernel/debug/memblock/reserved
   0: 0x00004000..0x00007fff
   1: 0x00100000..0x00e32b2f
   2: 0x08000000..0x080fffff
   3: 0x08300000..0x08318fff
   4: 0x083ff000..0x083fffff
   5: 0x2dc00000..0x3dbfffff
   6: 0x3df00000..0x3dfb7387
   7: 0x3ee41000..0x3ef3cfff
   8: 0x3ef3f480..0x3ef3f4f7
   9: 0x3ef3f500..0x3ef3f803
  10: 0x3ef3f834..0x3f7fefff
  11: 0x3f7ff040..0x3f7ff384
  12: 0x3f7ff3c0..0x3f7ff3fb
  13: 0x3f7ff400..0x3f7ff583
  14: 0x3f7ff5c0..0x3f7ff784
  15: 0x3f7ff7c0..0x3f7ff837
  16: 0x3f7ff840..0x3f7ff84f
  17: 0x3f7ff880..0x3f7ff88f
  18: 0x3f7ff8c0..0x3f7ff8c3
  19: 0x3f7ff900..0x3f7ff903
  20: 0x3f7ff940..0x3f7ffa4b
  21: 0x3f7ffa80..0x3f7ffb8b
  22: 0x3f7ffbc0..0x3f7ffccb
  23: 0x3f7ffcf0..0x3f7ffd08
  24: 0x3f7ffd0c..0x3f7ffd24
  25: 0x3f7ffd28..0x3f7ffd72
  26: 0x3f7ffd74..0x3f7ffd8e
  27: 0x3f7ffd90..0x3f7ffdaa
  28: 0x3f7ffdac..0x3f7ffdc6
  29: 0x3f7ffdc8..0x3f7ffde2
  30: 0x3f7ffde4..0x3f7ffdfe
  31: 0x3f7ffe00..0x3f7ffedf
  32: 0x3f7ffee8..0x3f7fff9f
  33: 0x3f7fffb0..0x3fffffff

zoneinfo​

  • cat /proc/zoneinfo

    Node 0, zone    DMA32
      per-node stats
          nr_inactive_anon 28250
          nr_active_anon 34245
          nr_inactive_file 29724
          nr_active_file 33943
          nr_unevictable 806
          nr_slab_reclaimable 10088
          nr_slab_unreclaimable 17495
          nr_isolated_anon 0
          nr_isolated_file 0
          workingset_refault 258089
          workingset_activate 54883
          workingset_restore 35120
          workingset_nodereclaim 4574
          nr_anon_pages 59384
          nr_mapped    65408
          nr_file_pages 70824
          nr_dirty     31
          nr_writeback 0
          nr_writeback_temp 0
          nr_shmem     1581
          nr_shmem_hugepages 0
          nr_shmem_pmdmapped 0
          nr_anon_transparent_hugepages 0
          nr_unstable  0
          nr_vmscan_write 148946
          nr_vmscan_immediate_reclaim 2540
          nr_dirtied   798484
          nr_written   938957
          nr_kernel_misc_reclaimable 0
          nr_unreclaimable_pages 0
          nr_ion_heap  0
          nr_ion_heap_pool 0
          nr_gpu_heap  0
      pages free     133183
            min      1221
            low      6006
            high     6380
            spanned  523776
            present  523776
            managed  374424
            protection: (0, 0, 0)
          nr_free_pages 133183
          nr_zone_inactive_anon 28250
          nr_zone_active_anon 34245
          nr_zone_inactive_file 29724
          nr_zone_active_file 33943
          nr_zone_unevictable 806
          nr_zone_write_pending 31
          nr_mlock     806
          nr_page_table_pages 10425
          nr_kernel_stack 18256
          nr_bounce    0
          nr_zspages   26061
          nr_free_cma  0
      pagesets
        cpu: 0
                  count: 342
                  high:  378
                  batch: 63
      vm stats threshold: 30
        cpu: 1
                  count: 301
                  high:  378
                  batch: 63
      vm stats threshold: 30
        cpu: 2
                  count: 32
                  high:  378
                  batch: 63
      vm stats threshold: 30
        cpu: 3
                  count: 296
                  high:  378
                  batch: 63
      vm stats threshold: 30
      node_unreclaimable:  0
      start_pfn:           512
    Node 0, zone   Normal
      pages free     0
            min      0
            low      0
            high     0
            spanned  0
            present  0
            managed  0
            protection: (0, 0, 0)
    Node 0, zone  Movable
      pages free     0
            min      0
            low      0
            high     0
            spanned  0
            present  0
            managed  0
            protection: (0, 0, 0)

Free Memory​

free​

  • total: Total memory managed by the kernel page allocator;

  • used: Memory currently in use;

  • free: Free memory;

  • shared: Shared memory, such as anonymous pages;

  • buffers: Buffer memory;

  • cached: Cache memory;

    The difference between buffers and cached. cached is used to accelerate reads, buffers is used to accelerate writes. cached saves read data in memory so that when reading again, the data can be read directly from memory instead of the hard disk, speeding up the read process. buffers temporarily saves scattered write operations in memory and writes them to the hard disk in batches when a certain threshold is reached, reducing disk fragmentation and repeated seeks, speeding up the write process.

free

                  total        used        free      shared     buffers
  Mem:       1533640704  1308901376   224739328     6422528      921600
-/+ buffers/cache:     1307979776   225660928
  Swap:       766816256   401342464   365473792

free -m

                  total        used        free      shared     buffers
  Mem:             1462        1249         213           6           0
-/+ buffers/cache:           1248         214
  Swap:             731         382         348

free -h

                  total        used        free      shared     buffers
  Mem:             1.4G        1.2G        212M        6.1M        900K
  -/+ buffers/cache:           1.2G        213M
  Swap:            731M        383M        349M

Clear Cache​

drop_caches​

  • echo x > /proc/sys/vm/drop_caches

    Clear pagecache

    echo 1 > /proc/sys/vm/drop_caches

    Clear dentries and inodes

    echo 2 > /proc/sys/vm/drop_caches

    Clear all caches (pagecache, dentries, and inodes)

    echo 3 > /proc/sys/vm/drop_caches

Virtual Memory Usage​

vmallocinfo​

  • cat /proc/vmallocinfo

    0x0000000000000000-0x0000000000000000    8192 bpf_jit_binary_alloc+0x70/0x110 pages=1 vmalloc
    ...
    0x0000000000000000-0x0000000000000000   20480 start_kernel+0x330/0x4f0 pages=4 vmalloc
    0x0000000000000000-0x0000000000000000    8192 of_iomap+0x4c/0xb8 phys=0x00000000fdd00000 ioremap
    0x0000000000000000-0x0000000000000000   20480 start_kernel+0x330/0x4f0 pages=4 vmalloc
    0x0000000000000000-0x0000000000000000    8192 of_iomap+0x4c/0xb8 phys=0x00000000fdd20000 ioremap
    0x0000000000000000-0x0000000000000000   20480 start_kernel+0x330/0x4f0 pages=4 vmalloc

vmstat​

  • cat /proc/vmstat

Memory Pressure​

pressure​

  • cat /proc/pressure/memory

  • VSS- Virtual Set Size (includes shared library memory)

  • RSS- Resident Set Size (actual physical memory used, includes shared library memory)

  • PSS- Proportional Set Size (actual physical memory used, proportionally allocated shared library memory)

  • USS- Unique Set Size (physical memory exclusively used by the process, does not include shared library memory)

Generally, memory usage follows this pattern: VSS >= RSS >= PSS >= USS