Commit 9f04b55f authored by Oliver Glitta's avatar Oliver Glitta Committed by Vlastimil Babka
Browse files

slab, documentation: add description of debugfs files for SLUB caches 



Add description of debugfs files alloc_traces and free_traces
to SLUB cache documentation.

[ vbabka@suse.cz: some rewording ]

Signed-off-by: default avatarOliver Glitta <glittao@gmail.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Reviewed-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
parent 553c0369

Documentation/vm/slub.rst

+64 −0
Original line number Diff line number Diff line
@@ -384,5 +384,69 @@ c) Execute ``slabinfo-gnuplot.sh`` in '-t' mode, passing all of the 
      40,60`` range will plot only samples collected between 40th and

      60th seconds).





DebugFS files for SLUB

======================



For more information about current state of SLUB caches with the user tracking

debug option enabled, debugfs files are available, typically under

/sys/kernel/debug/slab/<cache>/ (created only for caches with enabled user

tracking). There are 2 types of these files with the following debug

information:



1. alloc_traces::



    Prints information about unique allocation traces of the currently

    allocated objects. The output is sorted by frequency of each trace.



    Information in the output:

    Number of objects, allocating function, minimal/average/maximal jiffies since alloc,

    pid range of the allocating processes, cpu mask of allocating cpus, and stack trace.



    Example:::



    1085 populate_error_injection_list+0x97/0x110 age=166678/166680/166682 pid=1 cpus=1::

	__slab_alloc+0x6d/0x90

	kmem_cache_alloc_trace+0x2eb/0x300

	populate_error_injection_list+0x97/0x110

	init_error_injection+0x1b/0x71

	do_one_initcall+0x5f/0x2d0

	kernel_init_freeable+0x26f/0x2d7

	kernel_init+0xe/0x118

	ret_from_fork+0x22/0x30





2. free_traces::



    Prints information about unique freeing traces of the currently allocated

    objects. The freeing traces thus come from the previous life-cycle of the

    objects and are reported as not available for objects allocated for the first

    time. The output is sorted by frequency of each trace.



    Information in the output:

    Number of objects, freeing function, minimal/average/maximal jiffies since free,

    pid range of the freeing processes, cpu mask of freeing cpus, and stack trace.



    Example:::



    1980 <not-available> age=4294912290 pid=0 cpus=0

    51 acpi_ut_update_ref_count+0x6a6/0x782 age=236886/237027/237772 pid=1 cpus=1

	kfree+0x2db/0x420

	acpi_ut_update_ref_count+0x6a6/0x782

	acpi_ut_update_object_reference+0x1ad/0x234

	acpi_ut_remove_reference+0x7d/0x84

	acpi_rs_get_prt_method_data+0x97/0xd6

	acpi_get_irq_routing_table+0x82/0xc4

	acpi_pci_irq_find_prt_entry+0x8e/0x2e0

	acpi_pci_irq_lookup+0x3a/0x1e0

	acpi_pci_irq_enable+0x77/0x240

	pcibios_enable_device+0x39/0x40

	do_pci_enable_device.part.0+0x5d/0xe0

	pci_enable_device_flags+0xfc/0x120

	pci_enable_device+0x13/0x20

	virtio_pci_probe+0x9e/0x170

	local_pci_probe+0x48/0x80

	pci_device_probe+0x105/0x1c0



Christoph Lameter, May 30, 2007

Sergey Senozhatsky, October 23, 2015