Current versions of ODP linux-generic use sched_getaffinity() and / or
pthread_getaffinity_np() to obtain counts and sets of CPUs for use by
ODP tasks. This method returns inappropriate results when the
underlying kernel is compiled with NO_HZ_FULL support, as are the
current LNG kernels. See Linaro BUG 2027 for details.
https://bugs.linaro.org/show_bug.cgi?id=2027
Some of the validation and performance tests were using deprecated methods
for determining counts of available CPUs. Fixing the linux-generic
cpumask creation issues exposed the incorrect test code and caused these
tests to hang up. Since these tests are used to validate ODP linux-generic
code changes, fixing the tests became a prerequisite to submitting patches
to address BUG 2027... so patch 1 in this series addresses the test
faults. These test changes were confirmed to work properly whether the
bug 2027 fix is in place or not - they do not depend on the bug fix.
As to the bug fix itself, the 'getaffinity' CPU detection logic is
replaced by code which mines the /sysfs pseudo-filesystem for info
about the CPUs detected on the system at boot time.
In this third revision the bug fix code has been modified to behave thusly:
Per consensus based on discussions the new CPU detection logic by default
includes all installed CPUs in both the control and worker cpumasks.
Default cpumask generation is consistent with non-isolated operations.
All thread sibling cpumask optimization has been removed and the
added initialization stage marker for cpumasks has been removed as well.
Per a suggestion by Petri S. the cpumask generation is moved from the
odp_cpumask_default_control() and odp_cpumask_default_worker()
functions into the odp_init_global() function.
The odp_cpumask_default*() functions now use the cpumasks supplied by
odp_init_global() without modification - except for returning a mask
containing only the number of CPUs requested or the number available
(whichever is fewer) - when asked to provide a default worker cpumask.
As a bonus the bug fix cpumask generation logic also reduces the
number of changes required in order to support an anticipated
ODP API change which would allow ODP to accept and use control and
worker cpumasks specified by an external entity such as a provisioning
executive or a command-line argument parser.
Gary S. Robertson (2):
linux-generic: Correct worker count calculation in tests
linux-generic: Make cpu detection work with NO_HZ_FULL
platform/linux-generic/include/odp_internal.h | 6 ++
platform/linux-generic/odp_cpumask_task.c | 45 +++++++-------
platform/linux-generic/odp_init.c | 90 ++++++++++++++++++++++++++-
platform/linux-generic/odp_system_info.c | 14 ++---
test/performance/odp_atomic.c | 9 ++-
test/validation/cpumask/cpumask.c | 2 +-
test/validation/shmem/shmem.c | 5 +-
test/validation/timer/timer.c | 16 ++---
8 files changed, 139 insertions(+), 48 deletions(-)
--
1.9.1
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