I did some experiments to understand the impact of making 5 level page tables default. Machine Info: AMD Zen 4 EPYC server (2-socket system, 128 cores and 1 NUMA node per socket, SMT Enabled) Size of each NUMA node is approx 377 GB. For experiments, I'm binding the benchmark to CPUs and memory nodes of single socket for consistent results. Measured by enabling/disabling 5level Page table using CONFIG_X86_5LEVEL. % Change: (5L-4L)/4L*100 CoV (%): Coefficient of Variation (%) Results: lmbench:lat_pagefault: Metric- page-fault time (us) - Lower is better 4-Level PT 5-Level PT % Change THP-never Mean:0.4068 Mean:0.4294 5.56 95% CI:0.4057-0.4078 95% CI:0.4287-0.4302 THP-Always Mean: 0.4061 Mean: 0.4288 % Change 95% CI: 0.4051-0.4071 95% CI: 0.4281-0.4295 5.59 Btree (Thread:32): Metric- Time Taken (in seconds) - Lower is better 4-Level 5-Level Time Taken(s) CoV (%) Time Taken(s) CoV(%) % Change THP Never 382.2 0.219 388.8 1.019 1.73 THP Madvise 383.0 0.261 384.8 0.809 0.47 THP Always 392.8 1.376 386.4 2.147 -1.63 Btree (Thread:256): Metric- Time Taken (in seconds) - Lower is better 4-Level 5-Level Time Taken(s) CoV (%) Time Taken(s) CoV(%) % Change THP Never 56.6 2.014 55.2 0.810 -2.47 THP Madvise 56.6 2.014 56.4 2.022 -0.35 THP Always 56.6 0.968 56.2 1.489 -0.71 Ebizzy: Metric- records/s - Higher is better 4-Level 5-Level Threads record/s CoV (%) record/s CoV(%) % Change 1 844 0.302 837 0.196 -0.85 256 10160 0.315 10288 1.081 1.26 XSBench (Thread:256, THP:Never) - Higher is better Metric 4-Level 5-Level % Change Lookups/s 13720556 13396288 -2.36 CoV (%) 1.726 1.317 Hashjoin (Thread:256, THP:Never) - Lower is better Metric 4-Level 5-Level % Change Time taken(s) 424.4 427.4 0.707 CoV (%) 0.394 0.209 Graph500(Thread:256, THP:Madvise) - Lower is better Metric 4-Level 5-Level % Change Time Taken(s) 0.1879 0.1873 -0.32 CoV (%) 0.165 0.213 GUPS(Thread:128, THP:Madvise) - Higher is better Metric 4-Level 5-Level % Change GUPS 1.3265 1.3252 -0.10 CoV (%) 0.037 0.027 pagerank(Thread:256, THP:Madvise) - Lower is better Metric 4-Level 5-Level % Change Time taken(s) 143.67 143.67 0.00 CoV (%) 0.402 0.402 Redis(Thread:256, THP:Madvise) - Higher is better Metric 4-Level 5-Level % Change Throughput(Ops/s) 141030744 139586376 -1.02 CoV (%) 0.372 0.561 memcached(Thread:256, THP:Madvise) - Higher is better Metric 4-Level 5-Level % Change Throughput(Ops/s) 19916313 19743637 -0.87 CoV (%) 0.051 0.095 Inference: 5-level page table shows increase in page-fault latency but it does not significantly impact other benchmarks. Thanks, Shivank