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A mirror of the official Linux kernel repository just in case
3f21a6b7ef
This adds a new kernel module for analysis of vmalloc allocator. It is
only enabled as a module. There are two main reasons this module should
be used for: performance evaluation and stressing of vmalloc subsystem.
It consists of several test cases. As of now there are 8. The module
has five parameters we can specify to change its the behaviour.
1) run_test_mask - set of tests to be run
id: 1, name: fix_size_alloc_test
id: 2, name: full_fit_alloc_test
id: 4, name: long_busy_list_alloc_test
id: 8, name: random_size_alloc_test
id: 16, name: fix_align_alloc_test
id: 32, name: random_size_align_alloc_test
id: 64, name: align_shift_alloc_test
id: 128, name: pcpu_alloc_test
By default all tests are in run test mask. If you want to select some
specific tests it is possible to pass the mask. For example for first,
second and fourth tests we go 11 value.
2) test_repeat_count - how many times each test should be repeated
By default it is one time per test. It is possible to pass any number.
As high the value is the test duration gets increased.
3) test_loop_count - internal test loop counter. By default it is set
to 1000000.
4) single_cpu_test - use one CPU to run the tests
By default this parameter is set to false. It means that all online
CPUs execute tests. By setting it to 1, the tests are executed by
first online CPU only.
5) sequential_test_order - run tests in sequential order
By default this parameter is set to false. It means that before running
tests the order is shuffled. It is possible to make it sequential, just
set it to 1.
Performance analysis:
In order to evaluate performance of vmalloc allocations, usually it
makes sense to use only one CPU that runs tests, use sequential order,
number of repeat tests can be different as well as set of test mask.
For example if we want to run all tests, to use one CPU and repeat each
test 3 times. Insert the module passing following parameters:
single_cpu_test=1 sequential_test_order=1 test_repeat_count=3
with following output:
<snip>
Summary: fix_size_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 901177 usec
Summary: full_fit_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 1039341 usec
Summary: long_busy_list_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 11775763 usec
Summary: random_size_alloc_test passed 3: failed: 0 repeat: 3 loops: 1000000 avg: 6081992 usec
Summary: fix_align_alloc_test passed: 3 failed: 0 repeat: 3, loops: 1000000 avg:
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| .clang-format | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.