Revert "demand_paging: add NRU algorithm"
This reverts commit 200ea42437e7f4ff9aebdac3d5b9b1ead63d3e90.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/subsys/demand_paging/eviction/CMakeLists.txt b/subsys/demand_paging/eviction/CMakeLists.txt
index 4b28d8e..dd1bf80 100644
--- a/subsys/demand_paging/eviction/CMakeLists.txt
+++ b/subsys/demand_paging/eviction/CMakeLists.txt
@@ -1,14 +1,2 @@
# Copyright (c) 2020 Intel Corporation
# SPDX-License-Identifier: Apache-2.0
-
-add_definitions(-D__ZEPHYR_SUPERVISOR__)
-
-include_directories(
- ${ZEPHYR_BASE}/kernel/include
- ${ARCH_DIR}/${ARCH}/include
- )
-
-if(NOT DEFINED CONFIG_EVICTION_CUSTOM)
- zephyr_library()
- zephyr_library_sources_ifdef(CONFIG_EVICTION_NRU nru.c)
-endif()
diff --git a/subsys/demand_paging/eviction/Kconfig b/subsys/demand_paging/eviction/Kconfig
index 05f8b8d..0a39d9a 100644
--- a/subsys/demand_paging/eviction/Kconfig
+++ b/subsys/demand_paging/eviction/Kconfig
@@ -5,7 +5,7 @@
choice EVICTION_CHOICE
prompt "Page frame eviction algorithms"
- default EVICTION_NRU
+ default EVICTION_CUSTOM
depends on DEMAND_PAGING
config EVICTION_CUSTOM
@@ -14,27 +14,4 @@
This option is chosen when the eviction algorithm will be implemented
by the application, instead of using one included in Zephyr.
-config EVICTION_NRU
- bool "Not Recently Used (NRU) page eviction algorithm"
- help
- This implements a Not Recently Used page eviction algorithm.
- A periodic timer will clear the accessed state of all virtual pages.
- When a page frame needs to be evicted, the algorithm will prefer to
- evict page frames using an ascending order of priority:
-
- - recently accessed, dirty
- - recently accessed, clean
- - not recently accessed, dirty
- - not recently accessed, clean
-
endchoice
-
-if EVICTION_NRU
-config EVICTION_NRU_PERIOD
- int "Recently accessed period, in milliseconds"
- default 100
- help
- A periodic timer will fire that clears the accessed state of all virtual
- pages that are capable of being paged out. At eviction time, if a page
- still has the accessed property, it will be considered as recently used.
-endif # EVICTION_NRU
diff --git a/subsys/demand_paging/eviction/nru.c b/subsys/demand_paging/eviction/nru.c
deleted file mode 100644
index bfdb9ea..0000000
--- a/subsys/demand_paging/eviction/nru.c
+++ /dev/null
@@ -1,96 +0,0 @@
-/*
- * Copyright (c) 2020 Intel Corporation
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * Not Recently Used (NRU) eviction algorithm for demand paging
- */
-#include <kernel.h>
-#include <mmu.h>
-#include <kernel_arch_interface.h>
-#include <init.h>
-
-/* The accessed and dirty states of each page frame are used to create
- * a hierarchy with a numerical value. When evicting a page, try to evict
- * page with the highest value (we prefer clean, not accessed pages).
- *
- * In this ontology, "accessed" means "recently accessed" and gets cleared
- * during the periodic update.
- *
- * 0 not accessed, clean
- * 1 not accessed, dirty
- * 2 accessed, clean
- * 3 accessed, dirty
- */
-static void nru_periodic_update(struct k_timer *timer)
-{
- uintptr_t phys;
- struct z_page_frame *pf;
- int key = irq_lock();
-
- Z_PAGE_FRAME_FOREACH(phys, pf) {
- if (!z_page_frame_is_evictable(pf)) {
- continue;
- }
-
- /* Clear accessed bit in page tables */
- (void)arch_page_info_get(pf->addr, NULL, true);
- }
-
- irq_unlock(key);
-}
-
-struct z_page_frame *z_eviction_select(bool *dirty_ptr)
-{
- unsigned int last_prec = 4U;
- struct z_page_frame *last_pf = NULL, *pf;
- bool accessed;
- bool dirty = false;
- uintptr_t flags, phys;
-
- Z_PAGE_FRAME_FOREACH(phys, pf) {
- unsigned int prec;
-
- if (!z_page_frame_is_evictable(pf)) {
- continue;
- }
-
- flags = arch_page_info_get(pf->addr, NULL, false);
- accessed = (flags & ARCH_DATA_PAGE_ACCESSED) != 0UL;
- dirty = (flags & ARCH_DATA_PAGE_DIRTY) != 0UL;
-
- /* Implies a mismatch with page frame ontology and page
- * tables
- */
- __ASSERT((flags & ARCH_DATA_PAGE_LOADED) != 0U,
- "non-present page, %s",
- ((flags & ARCH_DATA_PAGE_NOT_MAPPED) != 0U) ?
- "un-mapped" : "paged out");
-
- prec = (dirty ? 1U : 0U) + (accessed ? 2U : 0U);
- if (prec == 0) {
- /* If we find a not accessed, clean page we're done */
- last_pf = pf;
- break;
- }
-
- if (prec < last_prec) {
- last_prec = prec;
- last_pf = pf;
- }
- }
- /* Shouldn't ever happen unless every page is pinned */
- __ASSERT(last_pf != NULL, "no page to evict");
-
- *dirty_ptr = dirty;
-
- return last_pf;
-}
-
-static K_TIMER_DEFINE(nru_timer, nru_periodic_update, NULL);
-
-void z_eviction_init(void)
-{
- k_timer_start(&nru_timer, K_NO_WAIT,
- K_MSEC(CONFIG_EVICTION_NRU_PERIOD));
-}
