From: SeongJae Park <sjpark@xxxxxxxxx> DAMON[1] is currently supporing only virtual memory address spaces of several target processes. Therefore, the user of DAMON should first select the target processes. This could be cumbersome in some cases and even makes no sense if the user want to monitor non-virtual address spaces. Especially, there were many requests and questions for support of physical memory monitoring. There were also many questions about use of different access check mechanisms such as dedicated H/W features[2], idle page tracking, or perf-mem, instead of the PTE Accessed bit checking, which is currently used by DAMON. Supporting various access check mechanisms will make DAMON to be highly tunable for specific cases. Fortunately, the core mechanisms of DAMON, the region-based sampling and adaptive regions adjustment, are not coupled with the virtual memory spaces and Accessed bit based access check. As long as there is a way to 1) address every region in the space and 2) check access to specific address, the core mechanisms could be applied. Nonetheless, current implementation of DAMON is highly coupled with the virtual memory address spaces. [1] https://lore.kernel.org/linux-mm/20200406130938.14066-1-sjpark@xxxxxxxxxx/ [2] https://images.anandtech.com/doci/10591/HC28.AMD.Mike%20Clark.final-page-016.jpg Baseline and Complete Git Trees =============================== The patches are based on the v5.6 plus DAMON v8 patchset[1] and DAMOS RFC v6[2] patchset. You can also clone the complete git tree: $ git clone git://github.com/sjp38/linux -b cdamon/rfc/v1 The web is also available: https://github.com/sjp38/linux/releases/tag/cdamon/rfc/v1 This patchset breaks the couplings and allows the target region definition and the access check to be configurable by users so that it can support various types of address spaces and use cases. Based on this patchset, you can configure DAMON to monitor physical memory or other special address spaces with your preferred access check mechanism. [1] https://lore.kernel.org/linux-mm/20200406130938.14066-1-sjpark@xxxxxxxxxx/ [2] https://lore.kernel.org/linux-mm/20200407100007.3894-1-sjpark@xxxxxxxxxx/ Sequence of Patches =================== The sequence of patches is as follow. The first patch defines the monitoring region again based on pure address range abstraction so that there is no assumption of virtual memory in there. The following patch cleans up code using the new abstraction. The third patch allows users to configure the initialization and dynamic update of the target address regions, which were highly coupled with virtual memory area, with their own things. Finally, the fourth patch further make the access check mechanism, which were based on PTE Accessed bit, configurable. SeongJae Park (4): mm/damon: Use vm-independent address range concept mm/damon: Clean up code using 'struct damon_addr_range' mm/damon: Make monitoring target regions init/update configurable mm/damon: Make access check configurable include/linux/damon.h | 15 +++- mm/damon-test.h | 82 ++++++++++---------- mm/damon.c | 174 ++++++++++++++++++++---------------------- 3 files changed, 136 insertions(+), 135 deletions(-) -- 2.17.1
