This is a O(1) LRU eviction algorithm. A bit more complex but way more
scalable than the NRU algorithm.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Let eviction algorithms be notified when a given page frame:
- should be considered as possible candidate
- should no longer be considered as candidate
- has just been marked as "accessed"
The NRU algorithm is unchanged so it implements those as empty stubs.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Currently, the NRU algorithm always picks the lowest (and very often the
same) clean unaccessed page over and over when e.g. doing large anonymous
memory mappings. Spread the eviction selection more uniformly by by
starting the search right after the last victim instead of always
restarting from 0.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
First, do align the buffer. The slab code puts pointers in there and it
does not like it if those are not properly aligned.
And return the actual error code from k_mem_slab_alloc() even if errors
shouldn't happen (it did happen to me because of the above ... with
assertions disabled).
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Also any demand paging and page frame related bits are
renamed.
This is part of a series to move memory management related
stuff out of the Z_ namespace into its own namespace.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This is part of a series to move memory management related
stuff from Z_ namespace into its own namespace.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Introduce z_page_frame_set() and z_page_frame_clear() to manipulate
flags. Obtain the virtual address using the existing
z_page_frame_to_virt(). This will make changes to the page frame
structure easier.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This moves including of demand_paging.h out of kernel/mm.h,
so that users of demand paging APIs must include the header
explicitly. Since the main user is kernel itself, we can be
more discipline about header inclusion.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Modify the signature of the k_mem_slab_free() function with a new one,
replacing the old void **mem with void *mem as a parameter.
The following function:
void k_mem_slab_free(struct k_mem_slab *slab, void **mem);
has the wrong signature. mem is only used as a regular pointer, so there
is no need to use a double-pointer. The correct signature should be:
void k_mem_slab_free(struct k_mem_slab *slab, void *mem);
The issue with the current signature, although functional, is that it is
extremely confusing. I myself, a veteran Zephyr developer, was confused
by this parameter when looking at it recently.
All in-tree uses of the function have been adapted.
Fixes#61888.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
irq_lock() returns an unsigned integer key.
Generated by spatch using semantic patch
scripts/coccinelle/irq_lock.cocci
Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
In order to bring consistency in-tree, migrate all subsystems code to
the new prefix <zephyr/...>. Note that the conversion has been scripted,
refer to zephyrproject-rtos#45388 for more details.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
In k_mem_paging_eviction_select(), the returned dirty bit value
may not be actually associated with the page selected, but
rather the last page examined. So fix this.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This adds a flash-based backing store for qemu_x86_tiny board for
testing demand paging. This allows us to test code execution where
.text section is not in physical memory at boot.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
These functions are those that need be implemented by backing
store outside kernel. Promote them from z_* so these can be
included in documentation.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
These functions and data structures are those that need
to be implemented by eviction algorithm and application
outside kernel. Promote them from z_* so these can be
included in documentation.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
If we evict enough pages to completely fill the backing store,
through APIs like k_mem_map(), z_page_frame_evict(), or
z_mem_page_out(), this will produce a crash the next time we
try to handle a page fault.
The backing store now always reserves a free storage location
for actual page faults.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Backing stores and eviction algorithms will be included here.
Exactly one must be chosen, with a default option to leave
the implementation to the application.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
If we evict enough pages to completely fill the backing store,
through APIs like k_mem_map(), z_page_frame_evict(), or
z_mem_page_out(), this will produce a crash the next time we
try to handle a page fault.
The backing store now always reserves a free storage location
for actual page faults.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Backing stores and eviction algorithms will be included here.
Exactly one must be chosen, with a default option to leave
the implementation to the application.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
