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But this is >>> not that. >>> >>> Nacked-by: Johannes Weiner >> >> Isn't every possible change to address this kind of issue subject to >> exactly the same kind of constraint? >> >> I'd like to know what not rolling that dice looks like :) or what >> constitutes 'careful evaluation'. > > Usama gave some great examples in his other email. I'm not really > arguing to keep things out of tradition. But I think it's fair to say > let's at least test the common 4k/2M THP setups under memory pressure > before and after the change. Hi, I tested this on an x86-64 (4K/2M) virtual machine with one NUMA node and 16 GiB online memory, using mmtests config-workload-thpchallenge-fio with THPCHALLENGE_MADV_HUGEPAGE=yes. min_free_kbytes was 16 MiB patched and 66 MiB unpatched. I ran each kernel 30 times, rebooting before each run. The results did not show a regression in THP fault success rate or latency: Average THP fault success (Percentage Faults Huge) increased from 13.07% unpatched to 13.34% patched, and average fault latency (Fault Latencies) decreased by 6.5%. In contrast, compaction metrics were higher on average with the patch: Compaction stalls: 1,635 -> 1,713 (+4.7%) Compaction failures: 1,350 -> 1,416 (+4.9%) Compaction migrate scanned: 4,812,254 -> 5,587,587 (+16.1%) Thanks,