On Tue, Mar 31, 2009 at 10:54:57AM -0500, Anthony Liguori wrote: > You can still disable ksm and simply return ENOSYS for the MADV_ flag. You -EINVAL if something, -ENOSYS would tell userland that it shall stop trying to use madvise, including the other MADV_ too. > could even keep it as a module if you liked by separating the madvise bits > from the ksm bits. The madvise() bits could just provide the tracking > infrastructure for determine which vmas were currently marked as sharable. > You could then have ksm as loadable module that consumed that interface to > then perform scanning. What's the point of making ksm a module if one has part of ksm code loaded in the kernel and not being possible to avoid compiling in? People that says KSM=N in their .config (like embedded running with 1M of ram), don't want that tracking overhead compiled into the kernel. Returning -EINVAL would be an option but again I think madvise is core syscall for SuS and I don't like that those core VM parts returns -EINVAL at will depend on certain kernel modules being loaded. > A number of MADV_ flags are Linux specific (like > MADV_DOFORK/MADV_DONTFORK). But those aren't kernel module related, so they're in line with the standard ones and could be adapted by other OS. KSM is not a core VM functionality, madvise is a core VM functionality, so I don't see fit. KSM as ioctl or KSM creating /proc/<pid>/ksm when loaded, sounds fine to me instead. If open of either one fails, application won't register in. It's up to you to choose KSM=M/N, if you want it as core functionality just build as KSM=Y but leave the option to others to save memory. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
