We don't have to claim we will read the value from variables when we do not,
this was only done to work around a bug on some versions of gcc for arm
a while ago, hopefully this won't be needed here.
This should fix the (harmless) warnings described in issue #83.
- ck_epoch_begin: Disallow early load of epoch as it leads to measurable
performance degradation in some benchmarks.
- ck_epoch_synchronize: Enforce barrier semantics.
Break out internal implementations to _mp and _sc variants from which
public interface is built on. Do not rely on macro. Adopt CK_CC_RESTRICT
instead of using restrict directly.
--platform let you set the platform, instead of relying on uname -m
--use-cc-builtins force the usage of gcc atomic builtins, instead of using the one provided by CK.
The atomicity of the sequence number's increment is unnecessary, since
there should be only one writer at any given time. Fix it by changing
it for a regular increment + store.
Signed-off-by: Emilio G. Cota <cota@braap.org>
This only affects RMO. This adds stricter semantics for critical section
serialization. In addition to this, asymmetric synchronization primitives will
now provide load ordering with respect to readers.
This also modifies locked operations to have acquire semantics
(they're there for elision predicates, and this doesn't impact them
in any way). There are several performance improvements included in this
as well (redundant fence was removed from days of wanting to support
Alpha).
These primitives are meant to be used in lock implementations
where control dependency ordering is sufficient to enforce
ordering of critical section. At the moment, this only affects
PPC. Currently, we rely on lwsync for entry into critical sections
which is insufficient. sync is rather heavy-weight, and assuming
we aren't falling victim into compiler re-ordering, isync should
be sufficient.
There is follow-up work to be done in ARM, as we may have cheaper
(but target-specialized) ISB-tricks for load-load ordering.
Olivier Houchard
alfredo
铁哥
Roman Lebedev
Samy Al Bahra
Paul Khuong
Michael Haberler
Samy Al Bahra
Emilio G. Cota