When everything is starting up we are likely to have a lot of child
processes producing output at once. This means that we can reduce
overhead a bit by allowing epoll_wait() to return more than one
descriptor at once, it cuts down on the number of system calls we need
to do which on virtual platforms where the syscall overhead is a bit
more noticable and we're likely to have a lot more children active can
make a small but noticable difference.
On physical platforms the relatively small number of processes being run
and vastly improved speeds push the effects of this change into the
noise.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221129215926.442895-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
At present fp-stress has a bit of a thundering herd problem since the
children it spawns start running immediately, meaning that they can start
starving the parent process of CPU before it has even started all the
children. This is much more severe on virtual platforms since they tend to
support far more SVE and SME vector lengths, be slower in general and for
some have issues with performance when simulating multiple CPUs.
We can mitigate this problem by having all the child processes block before
starting the test program, meaning that we at least have all the child
processes started before we start heavily using CPU. We still have the same
load issues while waiting for the actual stress test programs to start up
and produce output but they're at least all ready to go before that kicks
in, resulting in substantial reductions in overall runtime on some of the
severely affected systems. One test was showing about 20% improvement.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221129215926.442895-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Currently we don't have an explicit check that when it's been a second
since we have seen output produced from the test programs starting up that
means all of them are running and we should start both sending signals and
timing out. This is not reliable, especially on very heavily loaded systems
where the test programs might take longer than a second to run.
We do skip sending signals to children that have not produced output yet
so we won't cause them to exit unexpectedly by sending a signal but this
can create confusion when interpreting output, for example appearing to
show the tests running for less time than expected or appearing to show
missed signal deliveries. Avoid issues by explicitly checking that we have
seen output from all the child processes before we start sending signals
or counting test run time.
This is especially likely on virtual platforms with large numbers of vector
lengths supported since the platforms are slow and there will be a lot of
tasks per CPU.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221017144553.773176-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Currently we treat any error when reading from the child as a failure and
don't read any more output from that child as a result. This ignores the
fact that it is valid for read() to return EINTR as the error code if there
is a signal pending so we could stop handling the output of children,
especially during exit when we will get some SIGCHLD signals delivered to
us. Fix this by pulling the read handling out into a separate function
which returns a flag if reads should be continued and wrapping it in a
loop.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220921181345.618085-4-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
When fp-stress gets a termination signal it sets a flag telling itself to
exit and sends a termination signal to all the children. If the flag is set
then don't bother repeating this process, it isn't going to accomplish
anything other than consume CPU time which can be an issue when running in
emulation.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220921181345.618085-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently the stress test programs for floating point context switching are
run by hand, there are extremely simplistic harnesses which run some copies
of each test individually but they are not integrated into kselftest and
with SVE and SME they only run with whatever vector length the process has
by default. This is hassle when running the tests and means that they're
not being run at all by CI systems picking up kselftest.
In order to improve our coverage and provide a more convenient interface
provide a harness program which starts enough stress test programs up to
cause context switching and runs them for a set period. If only FPSIMD is
available in the system we start two copies of the FPSIMD stress test per
CPU, otherwise we start one copy of the FPSIMD and then start the SVE,
streaming SVE and ZA tests once per CPU for each available VL they have
to run on. We then run for a set period monitoring for any errors
reported by the test programs before cleanly terminating them.
In order to provide additional coverage of signal handling and some extra
noise in the scheduling we send a SIGUSR2 to the stress tests once a
second, the tests will count the number of signals they get.
Since kselftest is generally expected to run quickly we by default only run
for ten seconds. This is enough to show if there is anything cripplingly
wrong but not exactly a thorough soak test, for interactive and more
focused use a command line option -t N is provided which overrides the
length of time to run for (specified in seconds) and if 0 is specified then
there is no timeout and the test must be manually terminated. The timeout
is counted in seconds with no output, this is done to account for the
potentially slow startup time for the test programs on virtual platforms
which tend to struggle during startup as they are both slow and tend to
support a wide range of vector lengths.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154452.824870-5-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
To interface more robustly with other processes install the signal handers
in the floating point stress tests before we produce any output, this
means that a parent process can know that if it has seen any output from
the test then the test is ready to handle incoming signals.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220906220056.820295-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently the floating point stress tests mostly support testing that the
data they are checking can be disrupted from a signal handler triggered by
SIGUSR1. This is not properly implemented for all the tests and in testing
is frequently modified to just handle the signal without corrupting data in
order to ensure that signal handling does not corrupt data. Directly support
this usage by installing a SIGUSR2 handler which simply counts the signal
delivery.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154452.824870-3-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently the arm64 floating point tests don't support out of tree builds
due to two quirks of the kselftest build system. One is that when building
a program from multiple files we shouldn't separately compile the main
program to an object file as that will result in the pattern rule not
matching when adjusted for the output directory. The other is that we also
need to include $(OUTPUT) in the names of the binaries when specifying the
dependencies in order to ensure that they get picked up with O=.
Rewrite the dependencies for the executables to fix these issues. The
kselftest build system will ensure OUTPUT is always defined.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220427181954.357975-5-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The kselftest lib.mk provides a default all target which builds additional
programs from TEST_GEN_PROGS_EXTENDED, use that rather than using
TEST_PROGS_EXTENDED which is for programs that don't need to be built like
shell scripts. Leave fpsimd-stress and sve-stress there since they are
scripts.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220427181954.357975-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add a small testcase that attempts to do a clone() with ZA enabled and
verifies that it remains enabled with the same contents. We only check
one word in one horizontal vector of ZA since there's already other tests
that check for data corruption more broadly, we're just looking to make
sure that ZA is still enabled and it looks like the data got copied.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220419112247.711548-40-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add some basic coverage for the ZA ptrace interface, including walking
through all the vector lengths supported in the system. Unlike SVE
doing syscalls does not discard the ZA state so when we set data in ZA
we run the child process briefly, having it add one to each byte in ZA
in order to validate that both the vector size and data are being read
and written as expected when the process runs.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-38-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add a stress test for context switching of the ZA register state based on
the similar tests Dave Martin wrote for FPSIMD and SVE registers. The test
loops indefinitely writing a data pattern to ZA then reading it back and
verifying that it's what was expected.
Unlike the other tests we manually assemble the SME instructions since at
present no released toolchain has SME support integrated.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-35-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
One of the features of SME is the addition of streaming mode, in which we
have access to a set of streaming mode SVE registers at the SME vector
length. Since these are accessed using the SVE instructions let's reuse
the existing SVE stress test for testing with a compile time option for
controlling the few small differences needed:
- Enter streaming mode immediately on starting the program.
- In streaming mode FFR is removed so skip reading and writing FFR.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-33-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently we validate that we can set the floating point state via the SVE
regset and read the data via the FPSIMD regset but we do not valiate that
the opposite case works as expected. Add a test that covers this case,
noting that when reading via SVE regset the kernel has the option of
returning either SVE or FPSIMD data so we need to accept both formats.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220404090613.181272-4-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently the sve-ptrace test for setting and reading FPSIMD data assumes
that the child will start off in FPSIMD only mode and that it can use this
to read some FPSIMD mode SVE ptrace data, skipping the test if it can't.
This isn't an assumption guaranteed by the ABI and also limits how we can
use this testcase within the program. Instead skip the initial read and
just generate a FPSIMD format buffer for the write part of the test, making
the coverage more robust in the face of future kernel and test program
changes.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220404090613.181272-3-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
If the test triggers a problem it may well result in a log message from
the kernel such as a WARN() or BUG(). If these include a PID it can help
with debugging to know if it was the parent or child process that triggered
the issue, since the test is just creating a new thread the process name
will be the same either way. Print the PIDs of the parent and child on
startup so users have this information to hand should it be needed.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220303192817.2732509-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Currently we unconditionally test the ability to set the vector length
inheritance flag via ptrace meaning that we generate false failures on
systems that don't support SVE when we attempt to set the vector length
there. Check the hwcap and mark the tests as skipped when it's not present.
Fixes: 0ba1ce1e86 ("selftests: arm64: Add coverage of ptrace flags for SVE VL inheritance")
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220124175527.3260234-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Since it's likely to be useful for performance work with SVE let's have a
pidbench that gives us some numbers for consideration. In order to ensure
that we test exactly the scenario we want this is written in assembly - if
system libraries use SVE this would stop us exercising the case where the
process has never used SVE.
We exercise three cases:
- Never having used SVE.
- Having used SVE once.
- Using SVE after each syscall.
by spinning running getpid() for a fixed number of iterations with the
time measured using CNTVCT_EL0 reported on the console. This is obviously
a totally unrealistic benchmark which will show the extremes of any
performance variation but equally given the potential gotchas with use of
FP instructions by system libraries it's good to have some concrete code
shared to make it easier to compare notes on results.
Testing over multiple SVE vector lengths will need to be done with vlset
currently, the test could be extended to iterate over all of them if
desired.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211202165107.1075259-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
SME introduces a new mode called streaming mode in which the SVE registers
have a different vector length. Since the ptrace interface for this is
based on the existing SVE interface prepare for supporting this by moving
the regset specific configuration into struct and passing that around,
allowing these tests to be reused for streaming mode. As we will also have
to verify the interoperation of the SVE and streaming SVE regsets don't
just iterate over an array.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211210184133.320748-5-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
ARRAY_SIZE is defined in several selftests. Remove definitions from
individual test files and include header file for the define instead.
ARRAY_SIZE define is added in a separate patch to prepare for this
change.
Remove ARRAY_SIZE from vec-syscfg.c and pickup the one defined in
kselftest.h.
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
The various floating point test programs written in assembly have a bunch
of helper functions and macros which are cut'n'pasted between them. Factor
them out into a separate source file which is linked into all of them.
We don't include memcmp() since it isn't as generic as it should be and
directly branches to report an error in the programs.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211019181851.3341232-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
As part of the enumeration interface for setting vector lengths it is valid
to set vector lengths not supported in the system, these will be rounded to
a supported vector length and returned from the prctl(). Add a test which
exercises this for every valid vector length and makes sure that the return
value is as expected and that this is reflected in the actual system state.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20210929151925.9601-5-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
We had some test code for verifying that we can write the current VL via
the prctl() interface but the condition for the test was inverted which
wasn't noticed as it was never actually hooked up to the array of tests
we execute. Fix this.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210929151925.9601-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Currently the selftest for the SVE register set is not quite as thorough
as is desirable - it only validates that the value of a single Z register
is not modified by a partial write to a lower numbered Z register after
having previously been set through the FPSIMD regset.
Make this more thorough:
- Test the ability to set vector lengths and enumerate those supported in
the system.
- Validate data in all Z and P registers, plus FPSR and FPCR.
- Test reads via the FPSIMD regset after set via the SVE regset.
There's still some oversights, the main one being that due to the need to
generate a pattern in FFR and the fact that this rewrite is primarily
motivated by SME's streaming SVE which doesn't have FFR we don't currently
test FFR. Update the TODO to reflect those that occurred to me (and fix an
adjacent typo in there).
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-8-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
When verifying setting a Z register via ptrace we check each byte by hand,
iterating over the buffer using a pointer called p and treating each
register value written as a test. This creates output referring to "p[X]"
which is confusing since SVE also has predicate registers Pn. Tweak the
output to avoid confusion here.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-6-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
For some reason the SVE ptrace test code starts off by setting values in
some of the SVE vector registers in the parent process which it then never
interacts with when verifying the ptrace interfaces. This is not especially
relevant to what's being tested and somewhat confusing when reading the
code so let's remove it.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
