mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 18:14:07 +08:00
a984226f45
All the callers of mem_cgroup_page_lruvec() just pass page_pgdat(page) as the 2nd parameter to it (except isolate_migratepages_block()). But for isolate_migratepages_block(), the page_pgdat(page) is also equal to the local variable of @pgdat. So mem_cgroup_page_lruvec() do not need the pgdat parameter. Just remove it to simplify the code. Link: https://lkml.kernel.org/r/20210417043538.9793-4-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
626 lines
21 KiB
C
626 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Workingset detection
|
|
*
|
|
* Copyright (C) 2013 Red Hat, Inc., Johannes Weiner
|
|
*/
|
|
|
|
#include <linux/memcontrol.h>
|
|
#include <linux/mm_inline.h>
|
|
#include <linux/writeback.h>
|
|
#include <linux/shmem_fs.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/atomic.h>
|
|
#include <linux/module.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/dax.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/mm.h>
|
|
|
|
/*
|
|
* Double CLOCK lists
|
|
*
|
|
* Per node, two clock lists are maintained for file pages: the
|
|
* inactive and the active list. Freshly faulted pages start out at
|
|
* the head of the inactive list and page reclaim scans pages from the
|
|
* tail. Pages that are accessed multiple times on the inactive list
|
|
* are promoted to the active list, to protect them from reclaim,
|
|
* whereas active pages are demoted to the inactive list when the
|
|
* active list grows too big.
|
|
*
|
|
* fault ------------------------+
|
|
* |
|
|
* +--------------+ | +-------------+
|
|
* reclaim <- | inactive | <-+-- demotion | active | <--+
|
|
* +--------------+ +-------------+ |
|
|
* | |
|
|
* +-------------- promotion ------------------+
|
|
*
|
|
*
|
|
* Access frequency and refault distance
|
|
*
|
|
* A workload is thrashing when its pages are frequently used but they
|
|
* are evicted from the inactive list every time before another access
|
|
* would have promoted them to the active list.
|
|
*
|
|
* In cases where the average access distance between thrashing pages
|
|
* is bigger than the size of memory there is nothing that can be
|
|
* done - the thrashing set could never fit into memory under any
|
|
* circumstance.
|
|
*
|
|
* However, the average access distance could be bigger than the
|
|
* inactive list, yet smaller than the size of memory. In this case,
|
|
* the set could fit into memory if it weren't for the currently
|
|
* active pages - which may be used more, hopefully less frequently:
|
|
*
|
|
* +-memory available to cache-+
|
|
* | |
|
|
* +-inactive------+-active----+
|
|
* a b | c d e f g h i | J K L M N |
|
|
* +---------------+-----------+
|
|
*
|
|
* It is prohibitively expensive to accurately track access frequency
|
|
* of pages. But a reasonable approximation can be made to measure
|
|
* thrashing on the inactive list, after which refaulting pages can be
|
|
* activated optimistically to compete with the existing active pages.
|
|
*
|
|
* Approximating inactive page access frequency - Observations:
|
|
*
|
|
* 1. When a page is accessed for the first time, it is added to the
|
|
* head of the inactive list, slides every existing inactive page
|
|
* towards the tail by one slot, and pushes the current tail page
|
|
* out of memory.
|
|
*
|
|
* 2. When a page is accessed for the second time, it is promoted to
|
|
* the active list, shrinking the inactive list by one slot. This
|
|
* also slides all inactive pages that were faulted into the cache
|
|
* more recently than the activated page towards the tail of the
|
|
* inactive list.
|
|
*
|
|
* Thus:
|
|
*
|
|
* 1. The sum of evictions and activations between any two points in
|
|
* time indicate the minimum number of inactive pages accessed in
|
|
* between.
|
|
*
|
|
* 2. Moving one inactive page N page slots towards the tail of the
|
|
* list requires at least N inactive page accesses.
|
|
*
|
|
* Combining these:
|
|
*
|
|
* 1. When a page is finally evicted from memory, the number of
|
|
* inactive pages accessed while the page was in cache is at least
|
|
* the number of page slots on the inactive list.
|
|
*
|
|
* 2. In addition, measuring the sum of evictions and activations (E)
|
|
* at the time of a page's eviction, and comparing it to another
|
|
* reading (R) at the time the page faults back into memory tells
|
|
* the minimum number of accesses while the page was not cached.
|
|
* This is called the refault distance.
|
|
*
|
|
* Because the first access of the page was the fault and the second
|
|
* access the refault, we combine the in-cache distance with the
|
|
* out-of-cache distance to get the complete minimum access distance
|
|
* of this page:
|
|
*
|
|
* NR_inactive + (R - E)
|
|
*
|
|
* And knowing the minimum access distance of a page, we can easily
|
|
* tell if the page would be able to stay in cache assuming all page
|
|
* slots in the cache were available:
|
|
*
|
|
* NR_inactive + (R - E) <= NR_inactive + NR_active
|
|
*
|
|
* which can be further simplified to
|
|
*
|
|
* (R - E) <= NR_active
|
|
*
|
|
* Put into words, the refault distance (out-of-cache) can be seen as
|
|
* a deficit in inactive list space (in-cache). If the inactive list
|
|
* had (R - E) more page slots, the page would not have been evicted
|
|
* in between accesses, but activated instead. And on a full system,
|
|
* the only thing eating into inactive list space is active pages.
|
|
*
|
|
*
|
|
* Refaulting inactive pages
|
|
*
|
|
* All that is known about the active list is that the pages have been
|
|
* accessed more than once in the past. This means that at any given
|
|
* time there is actually a good chance that pages on the active list
|
|
* are no longer in active use.
|
|
*
|
|
* So when a refault distance of (R - E) is observed and there are at
|
|
* least (R - E) active pages, the refaulting page is activated
|
|
* optimistically in the hope that (R - E) active pages are actually
|
|
* used less frequently than the refaulting page - or even not used at
|
|
* all anymore.
|
|
*
|
|
* That means if inactive cache is refaulting with a suitable refault
|
|
* distance, we assume the cache workingset is transitioning and put
|
|
* pressure on the current active list.
|
|
*
|
|
* If this is wrong and demotion kicks in, the pages which are truly
|
|
* used more frequently will be reactivated while the less frequently
|
|
* used once will be evicted from memory.
|
|
*
|
|
* But if this is right, the stale pages will be pushed out of memory
|
|
* and the used pages get to stay in cache.
|
|
*
|
|
* Refaulting active pages
|
|
*
|
|
* If on the other hand the refaulting pages have recently been
|
|
* deactivated, it means that the active list is no longer protecting
|
|
* actively used cache from reclaim. The cache is NOT transitioning to
|
|
* a different workingset; the existing workingset is thrashing in the
|
|
* space allocated to the page cache.
|
|
*
|
|
*
|
|
* Implementation
|
|
*
|
|
* For each node's LRU lists, a counter for inactive evictions and
|
|
* activations is maintained (node->nonresident_age).
|
|
*
|
|
* On eviction, a snapshot of this counter (along with some bits to
|
|
* identify the node) is stored in the now empty page cache
|
|
* slot of the evicted page. This is called a shadow entry.
|
|
*
|
|
* On cache misses for which there are shadow entries, an eligible
|
|
* refault distance will immediately activate the refaulting page.
|
|
*/
|
|
|
|
#define EVICTION_SHIFT ((BITS_PER_LONG - BITS_PER_XA_VALUE) + \
|
|
1 + NODES_SHIFT + MEM_CGROUP_ID_SHIFT)
|
|
#define EVICTION_MASK (~0UL >> EVICTION_SHIFT)
|
|
|
|
/*
|
|
* Eviction timestamps need to be able to cover the full range of
|
|
* actionable refaults. However, bits are tight in the xarray
|
|
* entry, and after storing the identifier for the lruvec there might
|
|
* not be enough left to represent every single actionable refault. In
|
|
* that case, we have to sacrifice granularity for distance, and group
|
|
* evictions into coarser buckets by shaving off lower timestamp bits.
|
|
*/
|
|
static unsigned int bucket_order __read_mostly;
|
|
|
|
static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction,
|
|
bool workingset)
|
|
{
|
|
eviction >>= bucket_order;
|
|
eviction &= EVICTION_MASK;
|
|
eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid;
|
|
eviction = (eviction << NODES_SHIFT) | pgdat->node_id;
|
|
eviction = (eviction << 1) | workingset;
|
|
|
|
return xa_mk_value(eviction);
|
|
}
|
|
|
|
static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
|
|
unsigned long *evictionp, bool *workingsetp)
|
|
{
|
|
unsigned long entry = xa_to_value(shadow);
|
|
int memcgid, nid;
|
|
bool workingset;
|
|
|
|
workingset = entry & 1;
|
|
entry >>= 1;
|
|
nid = entry & ((1UL << NODES_SHIFT) - 1);
|
|
entry >>= NODES_SHIFT;
|
|
memcgid = entry & ((1UL << MEM_CGROUP_ID_SHIFT) - 1);
|
|
entry >>= MEM_CGROUP_ID_SHIFT;
|
|
|
|
*memcgidp = memcgid;
|
|
*pgdat = NODE_DATA(nid);
|
|
*evictionp = entry << bucket_order;
|
|
*workingsetp = workingset;
|
|
}
|
|
|
|
/**
|
|
* workingset_age_nonresident - age non-resident entries as LRU ages
|
|
* @lruvec: the lruvec that was aged
|
|
* @nr_pages: the number of pages to count
|
|
*
|
|
* As in-memory pages are aged, non-resident pages need to be aged as
|
|
* well, in order for the refault distances later on to be comparable
|
|
* to the in-memory dimensions. This function allows reclaim and LRU
|
|
* operations to drive the non-resident aging along in parallel.
|
|
*/
|
|
void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages)
|
|
{
|
|
/*
|
|
* Reclaiming a cgroup means reclaiming all its children in a
|
|
* round-robin fashion. That means that each cgroup has an LRU
|
|
* order that is composed of the LRU orders of its child
|
|
* cgroups; and every page has an LRU position not just in the
|
|
* cgroup that owns it, but in all of that group's ancestors.
|
|
*
|
|
* So when the physical inactive list of a leaf cgroup ages,
|
|
* the virtual inactive lists of all its parents, including
|
|
* the root cgroup's, age as well.
|
|
*/
|
|
do {
|
|
atomic_long_add(nr_pages, &lruvec->nonresident_age);
|
|
} while ((lruvec = parent_lruvec(lruvec)));
|
|
}
|
|
|
|
/**
|
|
* workingset_eviction - note the eviction of a page from memory
|
|
* @target_memcg: the cgroup that is causing the reclaim
|
|
* @page: the page being evicted
|
|
*
|
|
* Returns a shadow entry to be stored in @page->mapping->i_pages in place
|
|
* of the evicted @page so that a later refault can be detected.
|
|
*/
|
|
void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg)
|
|
{
|
|
struct pglist_data *pgdat = page_pgdat(page);
|
|
unsigned long eviction;
|
|
struct lruvec *lruvec;
|
|
int memcgid;
|
|
|
|
/* Page is fully exclusive and pins page's memory cgroup pointer */
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
VM_BUG_ON_PAGE(page_count(page), page);
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
|
|
lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
|
|
/* XXX: target_memcg can be NULL, go through lruvec */
|
|
memcgid = mem_cgroup_id(lruvec_memcg(lruvec));
|
|
eviction = atomic_long_read(&lruvec->nonresident_age);
|
|
workingset_age_nonresident(lruvec, thp_nr_pages(page));
|
|
return pack_shadow(memcgid, pgdat, eviction, PageWorkingset(page));
|
|
}
|
|
|
|
/**
|
|
* workingset_refault - evaluate the refault of a previously evicted page
|
|
* @page: the freshly allocated replacement page
|
|
* @shadow: shadow entry of the evicted page
|
|
*
|
|
* Calculates and evaluates the refault distance of the previously
|
|
* evicted page in the context of the node and the memcg whose memory
|
|
* pressure caused the eviction.
|
|
*/
|
|
void workingset_refault(struct page *page, void *shadow)
|
|
{
|
|
bool file = page_is_file_lru(page);
|
|
struct mem_cgroup *eviction_memcg;
|
|
struct lruvec *eviction_lruvec;
|
|
unsigned long refault_distance;
|
|
unsigned long workingset_size;
|
|
struct pglist_data *pgdat;
|
|
struct mem_cgroup *memcg;
|
|
unsigned long eviction;
|
|
struct lruvec *lruvec;
|
|
unsigned long refault;
|
|
bool workingset;
|
|
int memcgid;
|
|
|
|
unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset);
|
|
|
|
rcu_read_lock();
|
|
/*
|
|
* Look up the memcg associated with the stored ID. It might
|
|
* have been deleted since the page's eviction.
|
|
*
|
|
* Note that in rare events the ID could have been recycled
|
|
* for a new cgroup that refaults a shared page. This is
|
|
* impossible to tell from the available data. However, this
|
|
* should be a rare and limited disturbance, and activations
|
|
* are always speculative anyway. Ultimately, it's the aging
|
|
* algorithm's job to shake out the minimum access frequency
|
|
* for the active cache.
|
|
*
|
|
* XXX: On !CONFIG_MEMCG, this will always return NULL; it
|
|
* would be better if the root_mem_cgroup existed in all
|
|
* configurations instead.
|
|
*/
|
|
eviction_memcg = mem_cgroup_from_id(memcgid);
|
|
if (!mem_cgroup_disabled() && !eviction_memcg)
|
|
goto out;
|
|
eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat);
|
|
refault = atomic_long_read(&eviction_lruvec->nonresident_age);
|
|
|
|
/*
|
|
* Calculate the refault distance
|
|
*
|
|
* The unsigned subtraction here gives an accurate distance
|
|
* across nonresident_age overflows in most cases. There is a
|
|
* special case: usually, shadow entries have a short lifetime
|
|
* and are either refaulted or reclaimed along with the inode
|
|
* before they get too old. But it is not impossible for the
|
|
* nonresident_age to lap a shadow entry in the field, which
|
|
* can then result in a false small refault distance, leading
|
|
* to a false activation should this old entry actually
|
|
* refault again. However, earlier kernels used to deactivate
|
|
* unconditionally with *every* reclaim invocation for the
|
|
* longest time, so the occasional inappropriate activation
|
|
* leading to pressure on the active list is not a problem.
|
|
*/
|
|
refault_distance = (refault - eviction) & EVICTION_MASK;
|
|
|
|
/*
|
|
* The activation decision for this page is made at the level
|
|
* where the eviction occurred, as that is where the LRU order
|
|
* during page reclaim is being determined.
|
|
*
|
|
* However, the cgroup that will own the page is the one that
|
|
* is actually experiencing the refault event.
|
|
*/
|
|
memcg = page_memcg(page);
|
|
lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
|
|
|
inc_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file);
|
|
|
|
/*
|
|
* Compare the distance to the existing workingset size. We
|
|
* don't activate pages that couldn't stay resident even if
|
|
* all the memory was available to the workingset. Whether
|
|
* workingset competition needs to consider anon or not depends
|
|
* on having swap.
|
|
*/
|
|
workingset_size = lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE);
|
|
if (!file) {
|
|
workingset_size += lruvec_page_state(eviction_lruvec,
|
|
NR_INACTIVE_FILE);
|
|
}
|
|
if (mem_cgroup_get_nr_swap_pages(memcg) > 0) {
|
|
workingset_size += lruvec_page_state(eviction_lruvec,
|
|
NR_ACTIVE_ANON);
|
|
if (file) {
|
|
workingset_size += lruvec_page_state(eviction_lruvec,
|
|
NR_INACTIVE_ANON);
|
|
}
|
|
}
|
|
if (refault_distance > workingset_size)
|
|
goto out;
|
|
|
|
SetPageActive(page);
|
|
workingset_age_nonresident(lruvec, thp_nr_pages(page));
|
|
inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + file);
|
|
|
|
/* Page was active prior to eviction */
|
|
if (workingset) {
|
|
SetPageWorkingset(page);
|
|
/* XXX: Move to lru_cache_add() when it supports new vs putback */
|
|
lru_note_cost_page(page);
|
|
inc_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + file);
|
|
}
|
|
out:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/**
|
|
* workingset_activation - note a page activation
|
|
* @page: page that is being activated
|
|
*/
|
|
void workingset_activation(struct page *page)
|
|
{
|
|
struct mem_cgroup *memcg;
|
|
struct lruvec *lruvec;
|
|
|
|
rcu_read_lock();
|
|
/*
|
|
* Filter non-memcg pages here, e.g. unmap can call
|
|
* mark_page_accessed() on VDSO pages.
|
|
*
|
|
* XXX: See workingset_refault() - this should return
|
|
* root_mem_cgroup even for !CONFIG_MEMCG.
|
|
*/
|
|
memcg = page_memcg_rcu(page);
|
|
if (!mem_cgroup_disabled() && !memcg)
|
|
goto out;
|
|
lruvec = mem_cgroup_page_lruvec(page);
|
|
workingset_age_nonresident(lruvec, thp_nr_pages(page));
|
|
out:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* Shadow entries reflect the share of the working set that does not
|
|
* fit into memory, so their number depends on the access pattern of
|
|
* the workload. In most cases, they will refault or get reclaimed
|
|
* along with the inode, but a (malicious) workload that streams
|
|
* through files with a total size several times that of available
|
|
* memory, while preventing the inodes from being reclaimed, can
|
|
* create excessive amounts of shadow nodes. To keep a lid on this,
|
|
* track shadow nodes and reclaim them when they grow way past the
|
|
* point where they would still be useful.
|
|
*/
|
|
|
|
static struct list_lru shadow_nodes;
|
|
|
|
void workingset_update_node(struct xa_node *node)
|
|
{
|
|
/*
|
|
* Track non-empty nodes that contain only shadow entries;
|
|
* unlink those that contain pages or are being freed.
|
|
*
|
|
* Avoid acquiring the list_lru lock when the nodes are
|
|
* already where they should be. The list_empty() test is safe
|
|
* as node->private_list is protected by the i_pages lock.
|
|
*/
|
|
VM_WARN_ON_ONCE(!irqs_disabled()); /* For __inc_lruvec_page_state */
|
|
|
|
if (node->count && node->count == node->nr_values) {
|
|
if (list_empty(&node->private_list)) {
|
|
list_lru_add(&shadow_nodes, &node->private_list);
|
|
__inc_lruvec_kmem_state(node, WORKINGSET_NODES);
|
|
}
|
|
} else {
|
|
if (!list_empty(&node->private_list)) {
|
|
list_lru_del(&shadow_nodes, &node->private_list);
|
|
__dec_lruvec_kmem_state(node, WORKINGSET_NODES);
|
|
}
|
|
}
|
|
}
|
|
|
|
static unsigned long count_shadow_nodes(struct shrinker *shrinker,
|
|
struct shrink_control *sc)
|
|
{
|
|
unsigned long max_nodes;
|
|
unsigned long nodes;
|
|
unsigned long pages;
|
|
|
|
nodes = list_lru_shrink_count(&shadow_nodes, sc);
|
|
if (!nodes)
|
|
return SHRINK_EMPTY;
|
|
|
|
/*
|
|
* Approximate a reasonable limit for the nodes
|
|
* containing shadow entries. We don't need to keep more
|
|
* shadow entries than possible pages on the active list,
|
|
* since refault distances bigger than that are dismissed.
|
|
*
|
|
* The size of the active list converges toward 100% of
|
|
* overall page cache as memory grows, with only a tiny
|
|
* inactive list. Assume the total cache size for that.
|
|
*
|
|
* Nodes might be sparsely populated, with only one shadow
|
|
* entry in the extreme case. Obviously, we cannot keep one
|
|
* node for every eligible shadow entry, so compromise on a
|
|
* worst-case density of 1/8th. Below that, not all eligible
|
|
* refaults can be detected anymore.
|
|
*
|
|
* On 64-bit with 7 xa_nodes per page and 64 slots
|
|
* each, this will reclaim shadow entries when they consume
|
|
* ~1.8% of available memory:
|
|
*
|
|
* PAGE_SIZE / xa_nodes / node_entries * 8 / PAGE_SIZE
|
|
*/
|
|
#ifdef CONFIG_MEMCG
|
|
if (sc->memcg) {
|
|
struct lruvec *lruvec;
|
|
int i;
|
|
|
|
lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid));
|
|
for (pages = 0, i = 0; i < NR_LRU_LISTS; i++)
|
|
pages += lruvec_page_state_local(lruvec,
|
|
NR_LRU_BASE + i);
|
|
pages += lruvec_page_state_local(
|
|
lruvec, NR_SLAB_RECLAIMABLE_B) >> PAGE_SHIFT;
|
|
pages += lruvec_page_state_local(
|
|
lruvec, NR_SLAB_UNRECLAIMABLE_B) >> PAGE_SHIFT;
|
|
} else
|
|
#endif
|
|
pages = node_present_pages(sc->nid);
|
|
|
|
max_nodes = pages >> (XA_CHUNK_SHIFT - 3);
|
|
|
|
if (nodes <= max_nodes)
|
|
return 0;
|
|
return nodes - max_nodes;
|
|
}
|
|
|
|
static enum lru_status shadow_lru_isolate(struct list_head *item,
|
|
struct list_lru_one *lru,
|
|
spinlock_t *lru_lock,
|
|
void *arg) __must_hold(lru_lock)
|
|
{
|
|
struct xa_node *node = container_of(item, struct xa_node, private_list);
|
|
struct address_space *mapping;
|
|
int ret;
|
|
|
|
/*
|
|
* Page cache insertions and deletions synchronously maintain
|
|
* the shadow node LRU under the i_pages lock and the
|
|
* lru_lock. Because the page cache tree is emptied before
|
|
* the inode can be destroyed, holding the lru_lock pins any
|
|
* address_space that has nodes on the LRU.
|
|
*
|
|
* We can then safely transition to the i_pages lock to
|
|
* pin only the address_space of the particular node we want
|
|
* to reclaim, take the node off-LRU, and drop the lru_lock.
|
|
*/
|
|
|
|
mapping = container_of(node->array, struct address_space, i_pages);
|
|
|
|
/* Coming from the list, invert the lock order */
|
|
if (!xa_trylock(&mapping->i_pages)) {
|
|
spin_unlock_irq(lru_lock);
|
|
ret = LRU_RETRY;
|
|
goto out;
|
|
}
|
|
|
|
list_lru_isolate(lru, item);
|
|
__dec_lruvec_kmem_state(node, WORKINGSET_NODES);
|
|
|
|
spin_unlock(lru_lock);
|
|
|
|
/*
|
|
* The nodes should only contain one or more shadow entries,
|
|
* no pages, so we expect to be able to remove them all and
|
|
* delete and free the empty node afterwards.
|
|
*/
|
|
if (WARN_ON_ONCE(!node->nr_values))
|
|
goto out_invalid;
|
|
if (WARN_ON_ONCE(node->count != node->nr_values))
|
|
goto out_invalid;
|
|
xa_delete_node(node, workingset_update_node);
|
|
__inc_lruvec_kmem_state(node, WORKINGSET_NODERECLAIM);
|
|
|
|
out_invalid:
|
|
xa_unlock_irq(&mapping->i_pages);
|
|
ret = LRU_REMOVED_RETRY;
|
|
out:
|
|
cond_resched();
|
|
spin_lock_irq(lru_lock);
|
|
return ret;
|
|
}
|
|
|
|
static unsigned long scan_shadow_nodes(struct shrinker *shrinker,
|
|
struct shrink_control *sc)
|
|
{
|
|
/* list_lru lock nests inside the IRQ-safe i_pages lock */
|
|
return list_lru_shrink_walk_irq(&shadow_nodes, sc, shadow_lru_isolate,
|
|
NULL);
|
|
}
|
|
|
|
static struct shrinker workingset_shadow_shrinker = {
|
|
.count_objects = count_shadow_nodes,
|
|
.scan_objects = scan_shadow_nodes,
|
|
.seeks = 0, /* ->count reports only fully expendable nodes */
|
|
.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE,
|
|
};
|
|
|
|
/*
|
|
* Our list_lru->lock is IRQ-safe as it nests inside the IRQ-safe
|
|
* i_pages lock.
|
|
*/
|
|
static struct lock_class_key shadow_nodes_key;
|
|
|
|
static int __init workingset_init(void)
|
|
{
|
|
unsigned int timestamp_bits;
|
|
unsigned int max_order;
|
|
int ret;
|
|
|
|
BUILD_BUG_ON(BITS_PER_LONG < EVICTION_SHIFT);
|
|
/*
|
|
* Calculate the eviction bucket size to cover the longest
|
|
* actionable refault distance, which is currently half of
|
|
* memory (totalram_pages/2). However, memory hotplug may add
|
|
* some more pages at runtime, so keep working with up to
|
|
* double the initial memory by using totalram_pages as-is.
|
|
*/
|
|
timestamp_bits = BITS_PER_LONG - EVICTION_SHIFT;
|
|
max_order = fls_long(totalram_pages() - 1);
|
|
if (max_order > timestamp_bits)
|
|
bucket_order = max_order - timestamp_bits;
|
|
pr_info("workingset: timestamp_bits=%d max_order=%d bucket_order=%u\n",
|
|
timestamp_bits, max_order, bucket_order);
|
|
|
|
ret = prealloc_shrinker(&workingset_shadow_shrinker);
|
|
if (ret)
|
|
goto err;
|
|
ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key,
|
|
&workingset_shadow_shrinker);
|
|
if (ret)
|
|
goto err_list_lru;
|
|
register_shrinker_prepared(&workingset_shadow_shrinker);
|
|
return 0;
|
|
err_list_lru:
|
|
free_prealloced_shrinker(&workingset_shadow_shrinker);
|
|
err:
|
|
return ret;
|
|
}
|
|
module_init(workingset_init);
|