On 26.10.2012, at 03:17, Paul Mackerras wrote: > On Fri, Sep 14, 2012 at 03:15:32PM +0200, Alexander Graf wrote: >> >> On 14.09.2012, at 14:45, Paul Mackerras wrote: >> >>> On Fri, Sep 14, 2012 at 02:13:37PM +0200, Alexander Graf wrote: >>> >>>> So do you think it makes more sense to reimplement a large page allocator in KVM, as this patch set does, or improve CMA to get us really big chunks of linear memory? >>>> >>>> Let's ask the Linux mm guys too :). Maybe they have an idea. >>> >>> I asked the authors of CMA, and apparently it's not limited to >>> MAX_ORDER as I feared. It has the advantage that the memory can be >>> used for other things such as page cache when it's not needed, but not >>> for immovable allocations such as kmalloc. I'm going to try it out. >>> It will need a patch to increase the maximum alignment it allows. >> >> Awesome. Thanks a lot. I'd really prefer if we can stick to generic Linux solutions rather than invent our own :). > > Turns out there is a difficulty with this. When we have a guest page > that we want to pin in memory, and that page happens to have been > allocated within the CMA region, we would need to migrate it out of > the CMA region before pinning it, since otherwise it would reduce the > amount of contiguous memory available. But it appears that there > isn't any way to do that. How does this work for other users of CMA? I can't possibly believe that we only ever want a static amount of contiguous memory on the system. Alex -- 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