On 09/05/2012 01:06 AM, Andrew Morton wrote: > On Tue, 4 Sep 2012 11:41:19 +0300 > Haggai Eran <haggaie@xxxxxxxxxxxx> wrote: > >> > This patchset is a preliminary step towards on-demand paging design to be >> > added to the Infiniband stack. > > The above sentence is the most important part of the patchset. Because > it answers the question "ytf is Haggai sending this stuff at me". > > I'm unsure if the patchset adds runtime overhead but it does add > maintenance overhead (perhaps we can reduce this - see later emails). > So we need to take a close look at what we're getting in return for > that overhead, please. > > Exactly why do we want on-demand paging for Infiniband? Why should > anyone care? What problems are users currently experiencing? How many > users and how serious are the problems and what if any workarounds are > available? > > Is there any prospect that any other subsystems will utilise these > infrastructural changes? If so, which and how, etc? > > > > IOW, sell this code to us! kvm may be a buyer. kvm::mmu_lock, which serializes guest page faults, also protects long operations such as destroying large ranges. It would be good to convert it into a spinlock, but as it is used inside mmu notifiers, this cannot be done. (there are alternatives, such as keeping the spinlock and using a generation counter to do the teardown in O(1), which is what the "may" is doing up there). -- error compiling committee.c: too many arguments to function -- 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>