On Wed, Jun 10, 2015 at 03:51:05PM -0700, Ben Pfaff wrote: > On Tue, Jun 09, 2015 at 05:24:10PM -0700, Jarno Rajahalme wrote: > > This patch allows classifier rules to become visible and invisible in > > specific versions. A 'version' is defined as a positive monotonically > > increasing integer, which never wraps around. > > > > The new 'visibility' attribute replaces the prior 'to_be_removed' and > > 'visible' attributes. > > > > When versioning is not used, the 'version' parameter should be passed > > as 'CLS_MIN_VERSION' when creating rules, and 'CLS_MAX_VERSION' when > > looking up flows. > > > > This feature enables the support for atomic OpenFlow bundles without > > significant performance penalty on 64-bit systems. There is a > > performance decrease in 32-bit systems due to 64-bit atomics used. > > > > Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com> > > The two comments > > /* clang does not want to read from a const atomic. */ > > stand out to me a little, because they imply that this is a special > property of Clang. I don't think that's true; rather, it's a > consequence of the C standard definition, which defines atomic "load" > operations as taking plain types, not const-qualified ones. I think > that goes back, historically, to the definition of a "side effect" in C: > > Accessing a volatile object, modifying an object, modifying a file, > or calling a function that does any of those operations are all side > effects, which are changes in the state of the execution > environment. > > That is, *any* access to a volatile object (not just a write) is a side > effect (and thus cannot be optimized out by the compiler). I get the > impression that a lot of behavior for atomic types in C11 is related to > volatile types. > > Anyway, personally I'd either drop the comments or just s/clang/C11/. > > Acked-by: Ben Pfaff <b...@nicira.com>
This patch adds an XXX, is that removed in some later patch? _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
