On Tue, Apr 8, 2014 at 8:16 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > <snark> > > Of course, it would also be preferable if Amazon (or anything else) didn't need Xen PV :( Well Amazon doesn't expose NUMA on PV, only on HVM guests. > On April 7, 2014 9:04:53 PM PDT, Steven Noonan <steven@xxxxxxxxxxxxxx> wrote: >>On Mon, Apr 7, 2014 at 2:25 PM, Mel Gorman <mgorman@xxxxxxx> wrote: >>> On Mon, Apr 07, 2014 at 12:42:40PM -0700, H. Peter Anvin wrote: >>>> On 04/07/2014 12:36 PM, Cyrill Gorcunov wrote: >>>> > On Mon, Apr 07, 2014 at 12:27:10PM -0700, H. Peter Anvin wrote: >>>> >> On 04/07/2014 11:28 AM, Mel Gorman wrote: >>>> >>> >>>> >>> I had considered the soft-dirty tracking usage of the same bit. >>I thought I'd >>>> >>> be able to swizzle around it or a further worst case of having >>soft-dirty and >>>> >>> automatic NUMA balancing mutually exclusive. Unfortunately upon >>examination >>>> >>> it's not obvious how to have both of them share a bit and I >>suspect any >>>> >>> attempt to will break CRIU. In my current tree, NUMA_BALANCING >>cannot be >>>> >>> set if MEM_SOFT_DIRTY which is not particularly satisfactory. >>Next on the >>>> >>> list is examining if _PAGE_BIT_IOMAP can be used. >>>> >> >>>> >> Didn't we smoke the last user of _PAGE_BIT_IOMAP? >>>> > >>>> > Seems so, at least for non-kernel pages (not considering this bit >>references in >>>> > xen code, which i simply don't know but i guess it's used for >>kernel pages only). >>>> > >>>> >>>> David Vrabel has a patchset which I presumed would be pulled through >>the >>>> Xen tree this merge window: >>>> >>>> [PATCHv5 0/8] x86/xen: fixes for mapping high MMIO regions (and >>remove >>>> _PAGE_IOMAP) >>>> >>>> That frees up this bit. >>>> >>> >>> Thanks, I was not aware of that patch. Based on it, I intend to >>force >>> automatic NUMA balancing to depend on !XEN and see what the reaction >>is. If >>> support for Xen is really required then it potentially be re-enabled >>if/when >>> that series is merged assuming they do not need the bit for something >>else. >>> >> >>Amazon EC2 does have large memory instance types with NUMA exposed to >>the guest (e.g. c3.8xlarge, i2.8xlarge, etc), so it'd be preferable >>(to me anyway) if we didn't require !XEN. > > -- > Sent from my mobile phone. Please pardon brevity and lack of formatting. > > -- > 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>