> I agree that reporting the amount of shared pages in that historically fashion > might not be interesting for userspace tools resorting to sysinfo(2), > nowadays. > > OTOH, our documentation implies we do return shared memory there, and FWIW, > considering the other places we do export the "shared memory" concept to > userspace nowadays, we are suggesting it's the amount of tmpfs/shmem, and not the > amount of shared mapped pages it historiacally represented once. What is really > confusing is having a field that supposedely/expectedely would return the amount > of shmem to userspace queries, but instead returns a hard-coded zero (0). > > I could easily find out that there were some user complaint/confusion on this > semantic inconsistency in the past, as in: > https://groups.google.com/forum/#!topic/comp.os.linux.development.system/ogWVn6XdvGA > > or in: > http://marc.info/?l=net-snmp-cvs&m=132148788500667 > > which suggests users seem to always have understood it as being shmem/tmpfs > usage, as the /proc/meminfo field "MemShared" was tied direclty to > sysinfo.sharedram. Historically we reported shared memory that way, and > when it wasn't accurately meaning that anymore a 0 was hardcoded there to > potentially not break compatibility with older tools (older than 2.4). > In 2.6 we got rid of meminfo's "MemShared" until 2009, when you sort of > re-introduced it re-branded as Shmem. IMO, we should leverage what we > have in kernel now and take this change to make the exposed data consistent > across the interfaces that export it today -- sysinfo(2) & /proc/meminfo. > > This is not a hard requirement, though, but rather a simple maintenance > nitpick from code review. Ok, ack then. But please update a patch description and repost w/ ccing linux-api@xxxxxxxxxxxxxxx. Someone might have a specific concern about a compatibility. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>