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

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

[ vbabka@suse.cz: some rewording ]

Signed-off-by: Oliver Glitta <glittao@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
This commit is contained in:
Oliver Glitta 2021-06-08 10:45:17 +02:00 committed by Vlastimil Babka
parent 553c0369b3
commit 9f04b55f00
1 changed files with 64 additions and 0 deletions
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64
Documentation/vm/slub.rst
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@ -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