diff options
Diffstat (limited to 'Documentation/admin-guide/mm')
| -rw-r--r-- | Documentation/admin-guide/mm/damon/index.rst | 11 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/damon/usage.rst | 12 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/kho.rst | 115 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/multigen_lru.rst | 5 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/pagemap.rst | 1 |
6 files changed, 131 insertions, 14 deletions
diff --git a/Documentation/admin-guide/mm/damon/index.rst b/Documentation/admin-guide/mm/damon/index.rst index 33d37bb2fb4e..bc7e976120e0 100644 --- a/Documentation/admin-guide/mm/damon/index.rst +++ b/Documentation/admin-guide/mm/damon/index.rst @@ -1,12 +1,11 @@ .. SPDX-License-Identifier: GPL-2.0 -========================== -DAMON: Data Access MONitor -========================== +================================================================ +DAMON: Data Access MONitoring and Access-aware System Operations +================================================================ -:doc:`DAMON </mm/damon/index>` allows light-weight data access monitoring. -Using DAMON, users can analyze the memory access patterns of their systems and -optimize those. +:doc:`DAMON </mm/damon/index>` is a Linux kernel subsystem for efficient data +access monitoring and access-aware system operations. .. toctree:: :maxdepth: 2 diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index ced2013db3df..d960aba72b82 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -81,7 +81,7 @@ comma (","). │ │ │ │ │ │ │ :ref:`quotas <sysfs_quotas>`/ms,bytes,reset_interval_ms,effective_bytes │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil │ │ │ │ │ │ │ │ :ref:`goals <sysfs_schemes_quota_goals>`/nr_goals - │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value + │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid │ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low │ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,target_idx,min,max @@ -390,11 +390,11 @@ number (``N``) to the file creates the number of child directories named ``0`` to ``N-1``. Each directory represents each goal and current achievement. Among the multiple feedback, the best one is used. -Each goal directory contains three files, namely ``target_metric``, -``target_value`` and ``current_value``. Users can set and get the three -parameters for the quota auto-tuning goals that specified on the :ref:`design -doc <damon_design_damos_quotas_auto_tuning>` by writing to and reading from each -of the files. Note that users should further write +Each goal directory contains four files, namely ``target_metric``, +``target_value``, ``current_value`` and ``nid``. Users can set and get the +four parameters for the quota auto-tuning goals that specified on the +:ref:`design doc <damon_design_damos_quotas_auto_tuning>` by writing to and +reading from each of the files. Note that users should further write ``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond directory <sysfs_kdamond>` to pass the feedback to DAMON. diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst index 8b35795b664b..2d2f6c222308 100644 --- a/Documentation/admin-guide/mm/index.rst +++ b/Documentation/admin-guide/mm/index.rst @@ -42,3 +42,4 @@ the Linux memory management. transhuge userfaultfd zswap + kho diff --git a/Documentation/admin-guide/mm/kho.rst b/Documentation/admin-guide/mm/kho.rst new file mode 100644 index 000000000000..6dc18ed4b886 --- /dev/null +++ b/Documentation/admin-guide/mm/kho.rst @@ -0,0 +1,115 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +==================== +Kexec Handover Usage +==================== + +Kexec HandOver (KHO) is a mechanism that allows Linux to preserve memory +regions, which could contain serialized system states, across kexec. + +This document expects that you are familiar with the base KHO +:ref:`concepts <kho-concepts>`. If you have not read +them yet, please do so now. + +Prerequisites +============= + +KHO is available when the kernel is compiled with ``CONFIG_KEXEC_HANDOVER`` +set to y. Every KHO producer may have its own config option that you +need to enable if you would like to preserve their respective state across +kexec. + +To use KHO, please boot the kernel with the ``kho=on`` command line +parameter. You may use ``kho_scratch`` parameter to define size of the +scratch regions. For example ``kho_scratch=16M,512M,256M`` will reserve a +16 MiB low memory scratch area, a 512 MiB global scratch region, and 256 MiB +per NUMA node scratch regions on boot. + +Perform a KHO kexec +=================== + +First, before you perform a KHO kexec, you need to move the system into +the :ref:`KHO finalization phase <kho-finalization-phase>` :: + + $ echo 1 > /sys/kernel/debug/kho/out/finalize + +After this command, the KHO FDT is available in +``/sys/kernel/debug/kho/out/fdt``. Other subsystems may also register +their own preserved sub FDTs under +``/sys/kernel/debug/kho/out/sub_fdts/``. + +Next, load the target payload and kexec into it. It is important that you +use the ``-s`` parameter to use the in-kernel kexec file loader, as user +space kexec tooling currently has no support for KHO with the user space +based file loader :: + + # kexec -l /path/to/bzImage --initrd /path/to/initrd -s + # kexec -e + +The new kernel will boot up and contain some of the previous kernel's state. + +For example, if you used ``reserve_mem`` command line parameter to create +an early memory reservation, the new kernel will have that memory at the +same physical address as the old kernel. + +Abort a KHO exec +================ + +You can move the system out of KHO finalization phase again by calling :: + + $ echo 0 > /sys/kernel/debug/kho/out/active + +After this command, the KHO FDT is no longer available in +``/sys/kernel/debug/kho/out/fdt``. + +debugfs Interfaces +================== + +Currently KHO creates the following debugfs interfaces. Notice that these +interfaces may change in the future. They will be moved to sysfs once KHO is +stabilized. + +``/sys/kernel/debug/kho/out/finalize`` + Kexec HandOver (KHO) allows Linux to transition the state of + compatible drivers into the next kexec'ed kernel. To do so, + device drivers will instruct KHO to preserve memory regions, + which could contain serialized kernel state. + While the state is serialized, they are unable to perform + any modifications to state that was serialized, such as + handed over memory allocations. + + When this file contains "1", the system is in the transition + state. When contains "0", it is not. To switch between the + two states, echo the respective number into this file. + +``/sys/kernel/debug/kho/out/fdt`` + When KHO state tree is finalized, the kernel exposes the + flattened device tree blob that carries its current KHO + state in this file. Kexec user space tooling can use this + as input file for the KHO payload image. + +``/sys/kernel/debug/kho/out/scratch_len`` + Lengths of KHO scratch regions, which are physically contiguous + memory regions that will always stay available for future kexec + allocations. Kexec user space tools can use this file to determine + where it should place its payload images. + +``/sys/kernel/debug/kho/out/scratch_phys`` + Physical locations of KHO scratch regions. Kexec user space tools + can use this file in conjunction to scratch_phys to determine where + it should place its payload images. + +``/sys/kernel/debug/kho/out/sub_fdts/`` + In the KHO finalization phase, KHO producers register their own + FDT blob under this directory. + +``/sys/kernel/debug/kho/in/fdt`` + When the kernel was booted with Kexec HandOver (KHO), + the state tree that carries metadata about the previous + kernel's state is in this file in the format of flattened + device tree. This file may disappear when all consumers of + it finished to interpret their metadata. + +``/sys/kernel/debug/kho/in/sub_fdts/`` + Similar to ``kho/out/sub_fdts/``, but contains sub FDT blobs + of KHO producers passed from the old kernel. diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst index 33e068830497..9cb54b4ff5d9 100644 --- a/Documentation/admin-guide/mm/multigen_lru.rst +++ b/Documentation/admin-guide/mm/multigen_lru.rst @@ -151,8 +151,9 @@ generations less than or equal to ``min_gen_nr``. ``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. +overrides the default value in ``/proc/sys/vm/swappiness`` and the valid +range is [0-200, max], with max being exclusively used for the reclamation +of anonymous memory. ``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 diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst index afce291649dd..e60e9211fd9b 100644 --- a/Documentation/admin-guide/mm/pagemap.rst +++ b/Documentation/admin-guide/mm/pagemap.rst @@ -250,6 +250,7 @@ Following flags about pages are currently supported: - ``PAGE_IS_PFNZERO`` - Page has zero PFN - ``PAGE_IS_HUGE`` - Page is PMD-mapped THP or Hugetlb backed - ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty +- ``PAGE_IS_GUARD`` - Page is a part of a guard region The ``struct pm_scan_arg`` is used as the argument of the IOCTL. |