The patch titled thp: disable transparent hugepages by default on small systems has been added to the -mm tree. Its filename is thp-disable-transparent-hugepages-by-default-on-small-systems.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: thp: disable transparent hugepages by default on small systems From: Rik van Riel <riel@xxxxxxxxxx> On small systems, the extra memory used by the anti-fragmentation memory reserve and simply because huge pages are smaller than large pages can easily outweigh the benefits of less TLB misses. A less obvious concern is if run on a NUMA machine with asymmetric node sizes and one of them is very small. The reserve could make the node unusable. In case of the crashdump kernel, OOMs have been observed due to the anti-fragmentation memory reserve taking up a large fraction of the crashdump image. This patch disables transparent hugepages on systems with less than 1GB of RAM, but the hugepage subsystem is fully initialized so administrators can enable THP through /sys if desired. Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> Acked-by: Avi Kiviti <avi@xxxxxxxxxx> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Acked-by: Mel Gorman <mel@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff -puN mm/huge_memory.c~thp-disable-transparent-hugepages-by-default-on-small-systems mm/huge_memory.c --- a/mm/huge_memory.c~thp-disable-transparent-hugepages-by-default-on-small-systems +++ a/mm/huge_memory.c @@ -527,6 +527,14 @@ static int __init hugepage_init(void) goto out; } + /* + * By default disable transparent hugepages on smaller systems, + * where the extra memory used could hurt more than TLB overhead + * is likely to save. The admin can still enable it through /sys. + */ + if (totalram_pages < (512 << (20 - PAGE_SHIFT))) + transparent_hugepage_flags = 0; + start_khugepaged(); set_recommended_min_free_kbytes(); _ Patches currently in -mm which might be from riel@xxxxxxxxxx are linux-next.patch writeback-io-less-balance_dirty_pages.patch writeback-consolidate-variable-names-in-balance_dirty_pages.patch writeback-per-task-rate-limit-on-balance_dirty_pages.patch writeback-per-task-rate-limit-on-balance_dirty_pages-fix.patch writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls.patch writeback-account-per-bdi-accumulated-written-pages.patch writeback-bdi-write-bandwidth-estimation.patch writeback-bdi-write-bandwidth-estimation-fix.patch writeback-show-bdi-write-bandwidth-in-debugfs.patch writeback-quit-throttling-when-bdi-dirty-pages-dropped-low.patch writeback-reduce-per-bdi-dirty-threshold-ramp-up-time.patch writeback-make-reasonable-gap-between-the-dirty-background-thresholds.patch writeback-scale-down-max-throttle-bandwidth-on-concurrent-dirtiers.patch writeback-add-trace-event-for-balance_dirty_pages.patch writeback-make-nr_to_write-a-per-file-limit.patch writeback-make-nr_to_write-a-per-file-limit-fix.patch mm-compaction-add-trace-events-for-memory-compaction-activity.patch mm-vmscan-convert-lumpy_mode-into-a-bitmask.patch mm-vmscan-reclaim-order-0-and-use-compaction-instead-of-lumpy-reclaim.patch mm-vmscan-reclaim-order-0-and-use-compaction-instead-of-lumpy-reclaim-fix.patch mm-migration-allow-migration-to-operate-asynchronously-and-avoid-synchronous-compaction-in-the-faster-path.patch mm-migration-allow-migration-to-operate-asynchronously-and-avoid-synchronous-compaction-in-the-faster-path-fix.patch mm-migration-cleanup-migrate_pages-api-by-matching-types-for-offlining-and-sync.patch mm-compaction-perform-a-faster-migration-scan-when-migrating-asynchronously.patch mm-vmscan-rename-lumpy_mode-to-reclaim_mode.patch mm-vmscan-rename-lumpy_mode-to-reclaim_mode-fix.patch mm-deactivate-invalidated-pages.patch mm-deactivate-invalidated-pages-fix.patch oom-allow-a-non-cap_sys_resource-proces-to-oom_score_adj-down.patch mm-clear-pageerror-bit-in-msync-fsync.patch do_wp_page-remove-the-reuse-flag.patch do_wp_page-clarify-dirty_page-handling.patch mlock-avoid-dirtying-pages-and-triggering-writeback.patch mlock-only-hold-mmap_sem-in-shared-mode-when-faulting-in-pages.patch mm-add-foll_mlock-follow_page-flag.patch mm-move-vm_locked-check-to-__mlock_vma_pages_range.patch mlock-do-not-hold-mmap_sem-for-extended-periods-of-time.patch mlock-do-not-hold-mmap_sem-for-extended-periods-of-time-fix.patch mm-remove-likely-from-mapping_unevictable.patch mm-remove-unlikely-from-page_mapping.patch mm-kswapd-stop-high-order-balancing-when-any-suitable-zone-is-balanced.patch mm-kswapd-keep-kswapd-awake-for-high-order-allocations-until-a-percentage-of-the-node-is-balanced.patch mm-kswapd-use-the-order-that-kswapd-was-reclaiming-at-for-sleeping_prematurely.patch mm-kswapd-reset-kswapd_max_order-and-classzone_idx-after-reading.patch mm-kswapd-treat-zone-all_unreclaimable-in-sleeping_prematurely-similar-to-balance_pgdat.patch mm-kswapd-use-the-classzone-idx-that-kswapd-was-using-for-sleeping_prematurely.patch thp-fix-bad_page-to-show-the-real-reason-the-page-is-bad.patch thp-mm-define-madv_hugepage.patch thp-compound_lock.patch thp-alter-compound-get_page-put_page.patch thp-update-futex-compound-knowledge.patch thp-clear-compound-mapping.patch thp-add-native_set_pmd_at.patch thp-add-pmd-paravirt-ops.patch thp-no-paravirt-version-of-pmd-ops.patch thp-export-maybe_mkwrite.patch thp-comment-reminder-in-destroy_compound_page.patch thp-config_transparent_hugepage.patch thp-special-pmd_trans_-functions.patch thp-add-pmd-mangling-generic-functions.patch thp-add-pmd-mangling-functions-to-x86.patch thp-bail-out-gup_fast-on-splitting-pmd.patch thp-pte-alloc-trans-splitting.patch thp-add-pmd-mmu_notifier-helpers.patch thp-clear-page-compound.patch thp-add-pmd_huge_pte-to-mm_struct.patch thp-split_huge_page_mm-vma.patch thp-split_huge_page-paging.patch thp-clear_copy_huge_page.patch thp-_gfp_no_kswapd.patch thp-dont-alloc-harder-for-gfp-nomemalloc-even-if-nowait.patch thp-transparent-hugepage-core.patch thp-verify-pmd_trans_huge-isnt-leaking.patch thp-madvisemadv_hugepage.patch thp-pmd_trans_huge-migrate-bugcheck.patch thp-memcg-compound.patch thp-memcg-huge-memory.patch thp-transparent-hugepage-vmstat.patch thp-khugepaged.patch thp-skip-transhuge-pages-in-ksm-for-now.patch thp-add-x86-32bit-support.patch thp-mincore-transparent-hugepage-support.patch thp-add-pmd_modify.patch thp-mprotect-pass-vma-down-to-page-table-walkers.patch thp-mprotect-transparent-huge-page-support.patch thp-disable-transparent-hugepages-by-default-on-small-systems.patch thp-fix-anon-memory-statistics-with-transparent-hugepages.patch thp-scale-nr_rotated-to-balance-memory-pressure.patch thp-transparent-hugepage-sysfs-meminfo.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html