Subject: Re: [RFC PATCH v2 0/4] mm/damon: add a DAMOS filter type for page granularity access recheck In-Reply-To: <20240311204545.47097-1-sj@xxxxxxxxxx> Hi SeongJae, On Mon, 11 Mar 2024 13:45:41 -0700 SeongJae Park <sj@xxxxxxxxxx> wrote: > Changes from RFC v1 > (https://lore.kernel.org/r/20240307030013.47041-1-sj@xxxxxxxxxx) > - Rename __damon_pa_young() to damon_folio_young_one() > - Mark the folio as old from the filter for the next check > > DAMON allows users to specify desired ranges of overhead and accuracy of > the monitoring, and do its best effort to make most lightweight and > accurate results. A recent discussion for tiered memory management > support from DAMON[1] revealed that the best effort accuracy may not > suffice in some use cases, while increasing the minimum accuracy can > incur too high overhead. The discussion further concluded finding > memory regions of specific access pattern via DAMON first, and then > double checking the access of the region again in finer granularity > could help increasing the accuracy while keeping the low overhead. > > Add a new type of DAMOS filter, namely YOUNG for such a case. Like anon > and memcg, the type of filter is applied to each page of the memory > region of DAMOS target memory region, and check if the page is accessed > since the last check. Because this is a filter type that applied in > page granularity, the support depends on DAMON operations set. Because > there are expected usages of this filter for physical address space > based DAMOS usage[1], implement the support for only DAMON operations > set for the physical address space, paddr. > > [1] https://lore.kernel.org/r/20240227235121.153277-1-sj@xxxxxxxxxx > > > SeongJae Park (4): > mm/damon/paddr: implement damon_folio_young() > mm/damon/paddr: implement damon_folio_mkold() > mm/damon: add DAMOS filter type YOUNG > mm/damon/paddr: support DAMOS filter type YOUNG I have tested your patches for evaluation of [1] and it all works fine. Thanks very much for doing this work! Tested-by: Honggyu Kim <honggyu.kim@xxxxxx> [1] https://lore.kernel.org/damon/20240405060858.2818-1-honggyu.kim@xxxxxx > include/linux/damon.h | 2 ++ > mm/damon/paddr.c | 64 +++++++++++++++++++++++++--------------- > mm/damon/sysfs-schemes.c | 1 + > 3 files changed, 43 insertions(+), 24 deletions(-) > > > base-commit: 13043cde46a19e72d37965b67b74e564623f65e7 > -- > 2.39.2 >
