The property_benchmark needs to use the `load_default_path` parameter in
when writing its test, which is necessary now. Also, the benchmark
seemed to retry infinitely when the initialization failed, so it has now
been modified to exit when the initialization fails, and send a message
as it does so.
Bug: 305838406
Test: adb shell /data/benchmarktest/bionic-benchmarks/bionic-benchmarks --benchmark_filter=BM_property
Change-Id: Idb235b0e7c119fa08ace5b814d7f7404dd0eaeb3
Right now, when we read a system property, we first (assuming we've
already looked up the property's prop_info) read the property's serial
number; if we find that the low bit (the dirty bit) in the serial
number is set, we futex-wait for that serial number to become
non-dirty. By doing so, we spare readers from seeing partially-updated
property values if they race with the property service's non-atomic
memcpy to the property value slot. (The futex-wait here isn't
essential to the algorithm: spinning while dirty would suffice,
although it'd be somewhat less efficient.)
The problem with this approach is that readers can wait on the
property service process, potentially causing delays due to scheduling
variance. Property reads are not guaranteed to complete in finite time
right now.
This change makes property reads wait-free and ensures that they
complete in finite time in all cases. In the new approach, we prevent
value tearing by backing up each property we're about to modify and
directing readers to the backup copy if they try to read a property
with the dirty bit set.
(The wait freedom is limited to the case of readers racing against
*one* property update. A writer can still delay readers by rapidly
updating a property --- but after this change, readers can't hang due
to PID 1 scheduling delays.)
I considered adding explicit atomic access to short property values,
but between binary compatibility with the existing property database
and the need to carefully handle transitions of property values
between "short" (compatible with atomics) and "long" (incompatible
with atomics) length domains, I figured the complexity wasn't worth it
and that making property reads wait-free would be adequate.
Test: boots
Bug: 143561649
Change-Id: Ifd3108aedba5a4b157b66af6ca0a4ed084bd5982
With the goal of disallowing exit time destructors, SystemProperties's
non-trivial destructor needs to be removed. This means replacing the
union hack with yet another hack as we don't want to allocate anything
despite relying on some polymorphism.
Bug: 73485611
Test: boot bullhead
Change-Id: I64223714c9b26c9724bfb8f3e2b0168e47b56bc8
This change adds an end-to-end property benchmark that finds each
property currently accessible on the system via
__system_property_find().
Test: run this benchmark
Change-Id: I7d20cc9caf36bf3650c3bb3f58500b7df09a908a
Reinitializing system properties can result in crashes later in the
program, and is generally not recommended or even supported. This
change moves the actual logic for system properties into a class that
can be tested in isolation, without reinitializing the actual system
property area used in libc.
Bug: 62197783
Test: boot devices, ensure properties work
Test: system property unit tests and benchmarks
Change-Id: I9ae6e1b56c62f51a4d3fdb5b62b8926cef545649
Instead of requiring the need to maintain a list of all the benchmarks,
add a programmatic way to generate all of the benchmarks.
This generation runs the benchmarks in alphabetical order.
Add a new macro BIONIC_BENCHMARK_WITH_ARG that will be the default argument
to pass to the benchmark. Change the benchmarks that require default arguments.
Add a small example xml file, and remove the full.xml/host.xml files.
Update readme.
Test: Ran new unit tests, verified all tests are added.
Change-Id: I8036daeae7635393222a7a92d18f34119adba745
Apparently that "backdoor" is no longer needed - the proper way is
to reinitialize properties:
https://android-review.googlesource.com/#/c/181794/24/tests/system_properties_test.cpp
Also removes mentions of libnativehelper test (it no longer uses
__system_property_area__) and removes useless "extern" declaration
(actual use was removed long ago).
Test: refactoring CL, existsing tests still pass
BUG=21852512
BUG=34114501
Change-Id: I2223cab2fcb671ea180ad4470a7aba5c9cd20bd8
Changes:
- Modify the benchmarks to derive from a single Benchmark object.
- Rewrite the main iteration code. This includes changing the iteration
code to use the actual total time calculated by the benchmark as a basis
for determining whether there are enough iterations instead of using
the time it takes to run the benchmark.
- Allow benchmarks to take no argument, int, or double.
- Fix the PrettyInt printer for negative integers.
- Modify the max column width name to include the whole name including
the arg part.
- Reformat property_benchmark.cpp in line with the rest of the code.
- Modify a few of the math benchmarks to take an argument instead of
separate benchmarks for the same function with different args.
- Create a vector of regex_t structs to represent the args all at
once instead of when running each benchmark.
This change is in preparation for adding new math based benchmarks.
Tested by running on a nexus flo running at max using the new code
and the old code and comparing. All of the numbers are similar, but
some of the iterations are different due to the slightly different
algorithm used.
Change-Id: I57ad1f3ff083282b9ffeb72e687cab369ce3523a
Use the ANDROID_DATA environment variable instead of the hard-coded
directory for these benchmarks.
Change-Id: I00bae7b4a24e81e77fc8f52e1fe99f4d4918f520
