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It is often said that one of the biggest limitations on computer performanceis memory bandwidth (i.e."the memory wall problem"). In this position paper, Iargue that if historical trends in computing evolution (where growth inavailable capacity is exponential and reduction in its access latencies islinear) continue as they have, then this view is wrong - in fact we ought to beconcentrating on reducing whole system memory access latencies whereverpossible, and by "whole system" I mean that we ought to look at how softwarecan be unnecessarily wasteful with memory bandwidth due to legacy designdecisions. To this end I conduct a feasibility study to determine whether weought to virtualise the MMU for each application process such that it hasdirect access to its own MMU page tables and the memory allocated to a processis managed exclusively by the process and not the kernel. I find under typicalconditions that nearly scale invariant performance to memory allocation size ispossible such that hundreds of megabytes of memory can be allocated, relocated,swapped and deallocated in almost the same time as kilobytes (e.g. allocating8Mb is 10x quicker under this experimental allocator than a conventionalallocator, and resizing a 128Kb block to 256Kb block is 4.5x faster). I findthat first time page access latencies are improved tenfold; moreover, becausethe kernel page fault handler is never called, the lack of cache pollutionimproves whole application memory access latencies increasing performance by upto 2x. Finally, I try binary patching existing applications to use theexperimental allocation technique, finding almost universal performanceimprovements without having to recompile these applications to make better useof the new facilities.

User Mode Memory Page Management: An old idea applied anew to the memory wall problem