On Mon, 2013-08-12 at 16:25 -0500, Nathan Fontenot wrote: > On 08/12/2013 04:13 PM, Benjamin Herrenschmidt wrote: > > On Mon, 2013-08-12 at 08:01 -0500, Nathan Fontenot wrote: > >>> Can you tell me a bit more, the above makes me nervous... > >> > >> Ok, I agree. that message isn't quite right. > >> > >> What I wanted to convey is that memory hotplug is not fully supported > >> on powerpc with SPARSE_VMEMMAP enabled.. Perhaps the message should read > >> "Memory hotplug is not fully supported for bootmem info nodes". > >> > >> Thoughts? > > > > Since SPARSE_VMEMMAP is our default and enabled in our distros, that mean > > that memory hotplug isn't fully supported for us in general ? > > Actually... We have had the distros (at least SLES 11 and RHEL 6 releases) > disable SPARSE_VMEMMAP in their releases. Yuck ! That has a significant impact on performances... Additionally our VFIO implementation for KVM requires SPARSE_VMEMMAP. Why is it that this was never fixed in all these years ? > > > > What do you mean by "not fully supported" ? What precisely is missing ? > > What will happen if one tries to plug or unplug memory? > > I don't know everything that is missing, but there are several routines > that need to be defined for power to support memory hotplug with SPARSE_VMEMMAP. > > > > > Shouldn't we fix it ? > > Working on it, but it's not there yet. Ok, thanks. Cheers, Ben. > > > > Cheers, > > Ben. > > > > > > -- > 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> -- 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>