On 2012-11-15 14:44, telenn barz wrote: > On Thu, Nov 15, 2012 at 3:34 PM, Eric B Munson <emun...@mgebm.net > [1]> > wrote: > >> On 2012-11-15 03:42, telenn barz wrote: >> >>> Making some tests with libhugetlbfs on kernel 2.6.34, backing >>> automatically the heap, we realized that the fallback mechanism >>> is >>> all-or-nothing : if theres not enough hugepages, the whole asked >>> >>> memory is backed by base pages. >>> >>> We expected libhugetlbfs to mix hugepages / basepages in such a >>> case. >>> Would there be any issue with this requirement ? > >>> Thanks, >>> Telenn >> >> Telenn, >> >> This may be possible on x86/x86_64 but it isnt possible on POWER >> due to memory segment page size restrictions. To avoid having arch >> dependent morecore hooks we have not attempted this. > > Page size restrictions on POWER ? Could you please tell more about > this - in a few words ? >
Sure, PPC view memory in segments, for memory below 4GB these segments are 256MB, and I don't recall the segment size over 4GB. Inside a segment the page size must be uniform. So if morecore wanted to handle your version of fallback it would also have to know where it can place huge pages still. Eric ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Libhugetlbfs-devel mailing list Libhugetlbfs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libhugetlbfs-devel
