Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> writes: > Hi, > > Currently, on our ARM servers with NUMA enabled, we found the cross-die latency > is a little larger that will significantly impact the workload's performance. > So on ARM servers we will rely on the NUMA balancing to avoid the cross-die > accessing. And I posted a patchset[1] to support speculative numa fault to > improve the NUMA balancing's performance according to the principle of data > locality. Moreover, thanks to Huang Ying's patchset[2], which introduced batch > migration as a way to reduce the cost of TLB flush, and it will also benefit > the migration of multiple pages all at once during NUMA balancing. > > So we plan to continue to support batch migration in do_numa_page() to improve > the NUMA balancing's performance, but before adding complicated batch migration > algorithm for NUMA balancing, some cleanup and preparation work need to do firstly, > which are done in this patch set. In short, this patchset extends the > migrate_misplaced_page() interface to support batch migration, and no functional > changes intended. > > In addition, these cleanup can also benefit the compound page's NUMA balancing, > which was discussed in previous thread[3]. IIUC, for the compound page's NUMA > balancing, it is possible that partial pages were successfully migrated, so it is > necessary to return the number of pages that were successfully migrated from > migrate_misplaced_page(). But I don't find the return number is used except as bool now. Per my understanding, I still don't find much value of the changes except as preparation for batch migration in NUMA balancing. So I still think it's better to wait for the whole series. Where we can check why these changes are necessary for batch migration. And I think that you will provide some number to justify the batch migration, including pros and cons. -- Best Regards, Huang, Ying > This series is based on the latest mm-unstable(d226b59b30cc). > > [1] https://lore.kernel.org/lkml/cover.1639306956.git.baolin.wang@xxxxxxxxxxxxxxxxx/t/#mc45929849b5d0e29b5fdd9d50425f8e95b8f2563 > [2] https://lore.kernel.org/all/20230213123444.155149-1-ying.huang@xxxxxxxxx/T/#u > [3] https://lore.kernel.org/all/f8d47176-03a8-99bf-a813-b5942830fd73@xxxxxxx/ > > Changes from v1: > - Move page validation into a new function suggested by Huang Ying. > - Change numamigrate_isolate_page() to boolean type. > - Update some commit message. > > Baolin Wang (4): > mm: migrate: factor out migration validation into > numa_page_can_migrate() > mm: migrate: move the numamigrate_isolate_page() into do_numa_page() > mm: migrate: change migrate_misplaced_page() to support multiple pages > migration > mm: migrate: change to return the number of pages migrated > successfully > > include/linux/migrate.h | 15 +++++++--- > mm/huge_memory.c | 23 +++++++++++++-- > mm/internal.h | 1 + > mm/memory.c | 43 ++++++++++++++++++++++++++- > mm/migrate.c | 64 +++++++++-------------------------------- > 5 files changed, 88 insertions(+), 58 deletions(-)
