Link: https://lore.kernel.org/r/YvoOAJhJlvCr35Xc@xxxxxxxxxx/ Suggested-by: Mike Rapoport <rppt@xxxxxxxxxx> Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx> --- Documentation/admin-guide/mm/multigen_lru.rst | 50 +++++++++++-------- 1 file changed, 28 insertions(+), 22 deletions(-) diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst index 6355f2b5019d..33e068830497 100644 --- a/Documentation/admin-guide/mm/multigen_lru.rst +++ b/Documentation/admin-guide/mm/multigen_lru.rst @@ -119,15 +119,18 @@ within ``age_in_ms``. E.g., ``min_gen_nr`` contains the coldest pages and ``max_gen_nr`` contains the hottest pages, since ``age_in_ms`` of the former is the largest and that of the latter is the smallest. -Users can write ``+ memcg_id node_id max_gen_nr -[can_swap [force_scan]]`` to ``lru_gen`` to create a new generation -``max_gen_nr+1``. ``can_swap`` defaults to the swap setting and, if it -is set to ``1``, it forces the scan of anon pages when swap is off, -and vice versa. ``force_scan`` defaults to ``1`` and, if it is set to -``0``, it employs heuristics to reduce the overhead, which is likely -to reduce the coverage as well. +Users can write the following command to ``lru_gen`` to create a new +generation ``max_gen_nr+1``: -A typical use case is that a job scheduler writes to ``lru_gen`` at a + ``+ memcg_id node_id max_gen_nr [can_swap [force_scan]]`` + +``can_swap`` defaults to the swap setting and, if it is set to ``1``, +it forces the scan of anon pages when swap is off, and vice versa. +``force_scan`` defaults to ``1`` and, if it is set to ``0``, it +employs heuristics to reduce the overhead, which is likely to reduce +the coverage as well. + +A typical use case is that a job scheduler runs this command at a certain time interval to create new generations, and it ranks the servers it manages based on the sizes of their cold pages defined by this time interval. @@ -137,20 +140,23 @@ Proactive reclaim Proactive reclaim induces page reclaim when there is no memory pressure. It usually targets cold pages only. E.g., when a new job comes in, the job scheduler wants to proactively reclaim cold pages on -the server it selected to improve the chance of successfully landing +the server it selected, to improve the chance of successfully landing this new job. -Users can write ``- memcg_id node_id min_gen_nr [swappiness -[nr_to_reclaim]]`` to ``lru_gen`` to evict generations less than or -equal to ``min_gen_nr``. Note that ``min_gen_nr`` should be less than -``max_gen_nr-1`` as ``max_gen_nr`` and ``max_gen_nr-1`` are not fully -aged and therefore cannot be evicted. ``swappiness`` overrides the -default value in ``/proc/sys/vm/swappiness``. ``nr_to_reclaim`` limits -the number of pages to evict. +Users can write the following command to ``lru_gen`` to evict +generations less than or equal to ``min_gen_nr``. -A typical use case is that a job scheduler writes to ``lru_gen`` -before it tries to land a new job on a server. If it fails to -materialize enough cold pages because of the overestimation, it -retries on the next server according to the ranking result obtained -from the working set estimation step. This less forceful approach -limits the impacts on the existing jobs. + ``- memcg_id node_id min_gen_nr [swappiness [nr_to_reclaim]]`` + +``min_gen_nr`` should be less than ``max_gen_nr-1``, since +``max_gen_nr`` and ``max_gen_nr-1`` are not fully aged (equivalent to +the active list) and therefore cannot be evicted. ``swappiness`` +overrides the default value in ``/proc/sys/vm/swappiness``. +``nr_to_reclaim`` limits the number of pages to evict. + +A typical use case is that a job scheduler runs this command before it +tries to land a new job on a server. If it fails to materialize enough +cold pages because of the overestimation, it retries on the next +server according to the ranking result obtained from the working set +estimation step. This less forceful approach limits the impacts on the +existing jobs. -- 2.37.3.968.ga6b4b080e4-goog
