On 01/30/2017 05:03 PM, Anshuman Khandual wrote: > On 01/30/2017 10:49 PM, Dave Hansen wrote: >> On 01/29/2017 07:35 PM, Anshuman Khandual wrote: >>> HugeTLB allocation/release/accounting currently spans across all the nodes >>> under N_MEMORY node mask. Coherent memory nodes should not be part of these >>> allocations. So use system_ram() call to fetch system RAM only nodes on the >>> platform which can then be used for HugeTLB allocation purpose instead of >>> N_MEMORY node mask. This isolates coherent device memory nodes from HugeTLB >>> allocations. >> >> Does this end up making it impossible to use hugetlbfs to access device >> memory? > > Right, thats the implementation at the moment. But going forward if we need > to have HugeTLB pages on the CDM node, then we can implement through the > sysfs interface from individual NUMA node paths instead of changing the > generic HugeTLB path. I wrote this up in the cover letter but should also > have mentioned in the comment section of this patch as well. Does this > approach look okay ? The cover letter is not the most approachable document I've ever seen. :) > "Now, we ensure complete HugeTLB allocation isolation from CDM nodes. Going > forward if we need to support HugeTLB allocation on CDM nodes on targeted > basis, then we would have to enable those allocations through the > /sys/devices/system/node/nodeN/hugepages/hugepages-16384kB/nr_hugepages > interface while still ensuring isolation from other generic sysctl and > /sys/kernel/mm/hugepages/hugepages-16384kB/nr_hugepages interfaces." That would be passable if that's the only way you can allocate hugetlbfs pages. But we also have the fault-based allocations that can pull stuff right out of the buddy allocator. This approach would break that path entirely. FWIW, I think you really need to separate the true "CDM" stuff that's *really* device-specific from the parts of this from which you really just want to implement isolation. -- 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>
