On Tue, Sep 16, 2014 at 05:07:18PM -0700, Hugh Dickins wrote: > On the page migration issue: it's not quite as straightforward as > Christoph suggests. He and I agree completely that mlocked pages > should be migratable, but some real-time-minded people disagree: > so normal compaction is still forbidden to migrate mlocked pages in > the vanilla kernel (though we in Google patch that prohibition out). > So pinning by refcount is no worse for compaction than mlocking, > in the vanilla kernel. These realtime people are fully aware of this -- they should be at least, I've been telling them for years. Also, they would be very happy with means to actually pin pages -- as per the patches Christoph referred to. The advantage of also having mpin() and co is that we can migrate the memory into non-movable blocks before returning etc. In any case, I think we can (and should) change the behaviour of mlock to be migratable (possibly with an easy way to revert in -rt for migratory purposes until we get mpin sorted). -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
