This function allows for explicit execution of all
deferred callbacks in an epoch_record. The primary
motivation is currently for performance profiling
but there are other use-cases where best-effort
semantics could be applied.
Several counter-examples were found which break in the
presence of store-to-load re-ordering. Strict fence
semantics are necessary.
Thanks to Paul McKenney for helpful discussions.
These variants of ck_ring_enqueue_* return the snapshot of queue
length with respect to the linearization point. This can be used to
extract ring size without incurring additional cacheline invalidation
overhead from the writer.
John Wittrock has contributed a phase-fair reader-writer
lock implementation. These locks allow phase fairness
guarantees between readers and writers. This work includes
additional changes and clean-up.
Follow-up work is expected.
Thanks to John Wittrock for patches and Professor Gabriel
Parmer (http://www.seas.gwu.edu/~gparmer/) for advising.
Upon popular request, added a variant of the ticket spinlock
with trylock support. This is pending additional verification
on other architectures besides x86*. It is still unclear whether
this implementation will be the default as it is has slower
fast path.
Add trylock support to the ck_spinlock validation tests.
It currently only tests ck_spinlock_ticket_t trylock
functionality if available.
CK_LIST_INSERT_HEAD was incorrectly managing prev
pointer on insertion to non-empty list. This bug
would cause erroneous behavior on CK_LIST_REMOVE
to non-head elements. Unit test will be updated
for this regression.
An off-by-one was introduced in downgrade path from writer.
This can cause deadlock if a writer downgrades from a write lock.
Pointed out by Jeffrey Birnbaum <jmb...@...>.
Both LLVM-backed compilers and GCC incorrectly treat
a barrier-sandwiched load as a loop invariant in dequeue_spmc.
Forcing volatile atomic load semantics generates the right
thing.
Thanks to Devon O'Dell and Abel Mathew for help in catching
this issue.
The distinction between additive/exponential implementation
and geometric implementation does little but confuse users.
The terminology used in ck_backoff now reflects terminology
used in literature.
ck_backoff_gb has been removed.
Samy Al Bahra
Samy Al Bahra
Brendon Scheinman
Joao Fernandes
Abel Mathew