On Wed, 2015-12-16 at 16:54 +0100, Michael Kerrisk (man-pages) wrote: > Hello Darren, > > On 12/15/2015 10:18 PM, Darren Hart wrote: > > On Tue, Dec 15, 2015 at 02:43:50PM +0100, Michael Kerrisk (man-pages) wrote: > > [...] > > >> When executing a futex operation that requests to block a thread, > >> the kernel will block only if the futex word has the value that > >> the calling thread supplied (as one of the arguments of the > >> futex() call) as the expected value of the futex word. The load‐ > >> ing of the futex word's value, the comparison of that value with > >> the expected value, and the actual blocking will happen atomi‐ > >> > >> FIXME: for next line, it would be good to have an explanation of > >> "totally ordered" somewhere around here. > >> > >> cally and totally ordered with respect to concurrently executing > > > > Totally ordered with respect futex operations refers to semantics of the > > ACQUIRE/RELEASE operations and how they impact ordering of memory reads and > > writes. The kernel futex operations are protected by spinlocks, which ensure > > that that all operations are serialized with respect to one another. > > > > This is a lot to attempt to define in this document. Perhaps a reference to > > linux/Documentation/memory-barriers.txt as a footnote would be sufficient? > > Or > > perhaps for this manual, "serialized" would be sufficient, with a footnote > > regarding "totally ordered" and a pointer to the memory-barrier > > documentation? > > I think I'll just settle for writing serialized in the man page, and be > done with it :-).
I'd prefer if you'd not just use "serialized" :) Eventually, I'd prefer if we can explain the semantics for the user in terms of the terminology and semantics of the memory model of the programming language that users will likely use to call futex ops (ie, C11 / C++11). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
