diff options
Diffstat (limited to 'Documentation/mm')
| -rw-r--r-- | Documentation/mm/damon/design.rst | 18 | ||||
| -rw-r--r-- | Documentation/mm/damon/maintainer-profile.rst | 17 | ||||
| -rw-r--r-- | Documentation/mm/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/mm/physical_memory.rst | 2 | ||||
| -rw-r--r-- | Documentation/mm/swap-table.rst | 69 |
5 files changed, 94 insertions, 13 deletions
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst index 03f8137256f5..80354f4f42ba 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -67,7 +67,7 @@ processes, NUMA nodes, files, and backing memory devices would be supportable. Also, if some architectures or devices support special optimized access check features, those will be easily configurable. -DAMON currently provides below three operation sets. Below two subsections +DAMON currently provides below three operation sets. Below three subsections describe how those work. - vaddr: Monitor virtual address spaces of specific processes @@ -135,6 +135,20 @@ the interference is the responsibility of sysadmins. However, it solves the conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags, as Idle page tracking does. +.. _damon_design_addr_unit: + +Address Unit +------------ + +DAMON core layer uses ``unsinged long`` type for monitoring target address +ranges. In some cases, the address space for a given operations set could be +too large to be handled with the type. ARM (32-bit) with large physical +address extension is an example. For such cases, a per-operations set +parameter called ``address unit`` is provided. It represents the scale factor +that need to be multiplied to the core layer's address for calculating real +address on the given address space. Support of ``address unit`` parameter is +up to each operations set implementation. ``paddr`` is the only operations set +implementation that supports the parameter. .. _damon_core_logic: @@ -689,7 +703,7 @@ DAMOS accounts below statistics for each scheme, from the beginning of the scheme's execution. - ``nr_tried``: Total number of regions that the scheme is tried to be applied. -- ``sz_trtied``: Total size of regions that the scheme is tried to be applied. +- ``sz_tried``: Total size of regions that the scheme is tried to be applied. - ``sz_ops_filter_passed``: Total bytes that passed operations set layer-handled DAMOS filters. - ``nr_applied``: Total number of regions that the scheme is applied. diff --git a/Documentation/mm/damon/maintainer-profile.rst b/Documentation/mm/damon/maintainer-profile.rst index 5cd07905a193..58a3fb3c5762 100644 --- a/Documentation/mm/damon/maintainer-profile.rst +++ b/Documentation/mm/damon/maintainer-profile.rst @@ -89,18 +89,13 @@ the maintainer. Community meetup ---------------- -DAMON community is maintaining two bi-weekly meetup series for community -members who prefer synchronous conversations over mails. +DAMON community has a bi-weekly meetup series for members who prefer +synchronous conversations over mails. It is for discussions on specific topics +between a group of members including the maintainer. The maintainer shares the +available time slots, and attendees should reserve one of those at least 24 +hours before the time slot, by reaching out to the maintainer. -The first one is for any discussion between every community member. No -reservation is needed. - -The seconds one is for discussions on specific topics between restricted -members including the maintainer. The maintainer shares the available time -slots, and attendees should reserve one of those at least 24 hours before the -time slot, by reaching out to the maintainer. - -Schedules and available reservation time slots are available at the Google `doc +Schedules and reservation status are available at the Google `doc <https://docs.google.com/document/d/1v43Kcj3ly4CYqmAkMaZzLiM2GEnWfgdGbZAH3mi2vpM/edit?usp=sharing>`_. There is also a public Google `calendar <https://calendar.google.com/calendar/u/0?cid=ZDIwOTA4YTMxNjc2MDQ3NTIyMmUzYTM5ZmQyM2U4NDA0ZGIwZjBiYmJlZGQxNDM0MmY4ZTRjOTE0NjdhZDRiY0Bncm91cC5jYWxlbmRhci5nb29nbGUuY29t>`_ diff --git a/Documentation/mm/index.rst b/Documentation/mm/index.rst index fb45acba16ac..ba6a8872849b 100644 --- a/Documentation/mm/index.rst +++ b/Documentation/mm/index.rst @@ -20,6 +20,7 @@ see the :doc:`admin guide <../admin-guide/mm/index>`. highmem page_reclaim swap + swap-table page_cache shmfs oom diff --git a/Documentation/mm/physical_memory.rst b/Documentation/mm/physical_memory.rst index 9af11b5bd145..b76183545e5b 100644 --- a/Documentation/mm/physical_memory.rst +++ b/Documentation/mm/physical_memory.rst @@ -171,6 +171,8 @@ nodes with particular properties as defined by ``enum node_states``: The node has memory(regular, high, movable) ``N_CPU`` The node has one or more CPUs +``N_GENERIC_INITIATOR`` + The node has one or more Generic Initiators For each node that has a property described above, the bit corresponding to the node ID in the ``node_states[<property>]`` bitmask is set. diff --git a/Documentation/mm/swap-table.rst b/Documentation/mm/swap-table.rst new file mode 100644 index 000000000000..da10bb7a0dc3 --- /dev/null +++ b/Documentation/mm/swap-table.rst @@ -0,0 +1,69 @@ +.. SPDX-License-Identifier: GPL-2.0 + +:Author: Chris Li <chrisl@kernel.org>, Kairui Song <kasong@tencent.com> + +========== +Swap Table +========== + +Swap table implements swap cache as a per-cluster swap cache value array. + +Swap Entry +---------- + +A swap entry contains the information required to serve the anonymous page +fault. + +Swap entry is encoded as two parts: swap type and swap offset. + +The swap type indicates which swap device to use. +The swap offset is the offset of the swap file to read the page data from. + +Swap Cache +---------- + +Swap cache is a map to look up folios using swap entry as the key. The result +value can have three possible types depending on which stage of this swap entry +was in. + +1. NULL: This swap entry is not used. + +2. folio: A folio has been allocated and bound to this swap entry. This is + the transient state of swap out or swap in. The folio data can be in + the folio or swap file, or both. + +3. shadow: The shadow contains the working set information of the swapped + out folio. This is the normal state for a swapped out page. + +Swap Table Internals +-------------------- + +The previous swap cache is implemented by XArray. The XArray is a tree +structure. Each lookup will go through multiple nodes. Can we do better? + +Notice that most of the time when we look up the swap cache, we are either +in a swap in or swap out path. We should already have the swap cluster, +which contains the swap entry. + +If we have a per-cluster array to store swap cache value in the cluster. +Swap cache lookup within the cluster can be a very simple array lookup. + +We give such a per-cluster swap cache value array a name: the swap table. + +A swap table is an array of pointers. Each pointer is the same size as a +PTE. The size of a swap table for one swap cluster typically matches a PTE +page table, which is one page on modern 64-bit systems. + +With swap table, swap cache lookup can achieve great locality, simpler, +and faster. + +Locking +------- + +Swap table modification requires taking the cluster lock. If a folio +is being added to or removed from the swap table, the folio must be +locked prior to the cluster lock. After adding or removing is done, the +folio shall be unlocked. + +Swap table lookup is protected by RCU and atomic read. If the lookup +returns a folio, the user must lock the folio before use. |