Normally, I/O completed pages for reclaim would be rotated into inactive LRU tail without freeing. The why it works is we can't free page from atomic context(ie, end_page_writeback) due to vaious locks isn't aware of atomic context.
So for reclaiming the I/O completed pages, we need one more iteration of reclaim and it could make unnecessary aging as well as CPU overhead. Long time ago, at the first trial, most concern was memcg locking but recently, Johnannes tried amazing effort to make memcg lock simple and got merged into mmotm so I coded up based on mmotm tree. (Kudos to Johannes) On 1G, 12 CPU kvm guest, build kernel 5 times and result was allocstall vanilla: records: 5 avg: 4733.80 std: 913.55(19.30%) max: 6442.00 min: 3719.00 improve: records: 5 avg: 1514.20 std: 441.69(29.17%) max: 1974.00 min: 863.00 pgrotated vanilla: records: 5 avg: 873313.80 std: 40999.20(4.69%) max: 954722.00 min: 845903.00 improve: records: 5 avg: 28406.40 std: 3296.02(11.60%) max: 34552.00 min: 25047.00 Most of field in vmstat are not changed too much but things I can notice is allocstall and pgrotated. We could save allocstall(ie, direct relcaim) and pgrotated very much. Welcome testing, review and any feedback! * from v2 - 2014.06.20 * Rebased on v3.16-rc2-mmotm-2014-06-25-16-44 * Remove RFC tag Minchan Kim (3): mm: Don't hide spin_lock in swap_info_get internal mm: Introduce atomic_remove_mapping mm: Free reclaimed pages indepdent of next reclaim include/linux/swap.h | 4 ++++ mm/filemap.c | 17 +++++++++----- mm/swap.c | 21 ++++++++++++++++++ mm/swapfile.c | 17 ++++++++++++-- mm/vmscan.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 114 insertions(+), 8 deletions(-) -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
