福奇亞的記憶力重塑

// Create a discardable VMO.
zx_handle_t vmo;
uint64_t vmo_size = 5 * zx_system_get_page_size();
zx_vmo_create(vmo_size, ZX_VMO_DISCARDABLE, &vmo);

// Lock the VMO.
zx_vmo_lock_state_t lock_state = {};
zx_vmo_op_range(vmo, ZX_VMO_OP_LOCK, 0, vmo_size, &lock_state,
                sizeof(lock_state));

// Use the VMO as desired.
zx_vmo_read(vmo, buf, 0, sizeof(buf));

// Unlock the VMO. The kernel is free to discard it now.
zx_vmo_op_range(vmo, ZX_VMO_OP_UNLOCK, 0, vmo_size, nullptr, 0);

// Lock the VMO again before use.
zx_vmo_op_range(vmo, ZX_VMO_OP_LOCK, 0, vmo_size, &lock_state,
                sizeof(lock_state));

if (lock_state.discarded_size > 0) {
  // The kernel discarded the VMO. Re-initialize it if required.
  zx_vmo_write(vmo, data, 0, sizeof(data));
} else {
  // The kernel did not discard the VMO. Previous contents were preserved.
}

k scanner
usage:
scanner dump                    : dump scanner info
scanner push_disable            : increase scanner disable count
scanner pop_disable             : decrease scanner disable count
scanner reclaim_all             : attempt to reclaim all possible memory
scanner rotate_queue            : immediately rotate the page queues
scanner reclaim <MB> [only_old] : attempt to reclaim requested MB of memory.
scanner pt_reclaim [on|off]     : turn unused page table reclamation on or off
scanner harvest_accessed        : harvest all page accessed information

k scanner dump
[SCAN]: Scanner enabled. Triggering informational scan
[SCAN]: Found 4303 zero pages across all of memory
[SCAN]: Found 8995 user-pager backed pages in queue 0
[SCAN]: Found 3278 user-pager backed pages in queue 1
[SCAN]: Found 8947 user-pager backed pages in queue 2
[SCAN]: Found 10776 user-pager backed pages in queue 3
[SCAN]: Found 3981 user-pager backed pages in queue 4
[SCAN]: Found 0 user-pager backed pages in queue 5
[SCAN]: Found 0 user-pager backed pages in queue 6
[SCAN]: Found 0 user-pager backed pages in queue 7
[SCAN]: Found 1347 user-pager backed pages in DontNeed queue
[SCAN]: Found 40 zero forked pages
[SCAN]: Found 0 locked pages in discardable vmos
[SCAN]: Found 0 unlocked pages in discardable vmos
pq: MRU generation is 12 set 10.720698018s ago due to "Active ratio", LRU generation is 6
pq: Pager buckets [8995],[3278],8947,10776,3981,0,{0},0, evict first: 1347, live active/inactive totals: 12273/25051

k scanner reclaim_all
[EVICT]: Free memory before eviction was 7161MB and after eviction is 7290MB
[EVICT]: Evicted 33004 user pager backed pages
[SCAN]: De-duped 25 pages that were recently forked from the zero page

k pmm
…
pmm drop_user_pt                             : drop all user hardware page tables

k mem avail_state
mem avail_state [step] <state> [<nsecs>] : allocate memory to go to memstate <state>, hold the state for <nsecs> (10s by default). Only works if going to <state> from current state requires allocating memory, can't free up pre-allocated memory. In optional [step] mode, allocation pauses for 1 second at each intermediate memory availability state until <state> is reached.

k mem dump
watermarks: [50M, 60M, 150M, 300M]
debounce: 1M
current state: 4
current bounds: [299M, 16.0E]
free memory: 7253.5M

OOM: 50MB, Imminent-OOM: 60MB, Critical: 150MB, Warning: 300MB

k mem avail_state 2
memory-pressure: memory availability state - Critical
pq: MRU generation is 714 set 4.144414945s ago due to "Active ratio", LRU generation is 708
pq: Pager buckets [3482],[115],317,0,199,0,{6939},0, evict first: 0, live active/inactive totals: 3597/7455
memory-pressure: set target memory to evict 1MB (free memory is 149MB)
Leaked 1817528 pages
Sleeping for 10 seconds...
[EVICT]: Free memory before eviction was 147MB and after eviction is 151MB
[EVICT]: Evicted 986 user pager backed pages
Freed 1817528 pages
memory-pressure: memory availability state - Normal
pq: MRU generation is 717 set 1.213355379s ago due to "Timeout", LRU generation is 711
pq: Pager buckets [4351],[258],149,37,0,1,{5798},0, evict first: 0, live active/inactive totals: 4609/5985

mem oom [<rate>]                             : leak memory until oom is triggered, optionally specify the rate at which to leak (in MB per second)
mem oom hard                                 : leak memory aggressively and keep on leaking
mem oom signal                               : trigger oom signal without leaking memory

k mem oom
Disabling VM scanner
memory-pressure: free memory is 49MB, evicting pages to prevent OOM...
pq: MRU generation is 13 set 7.979442243s ago due to "Active ratio", LRU generation is 7
pq: Pager buckets [4538],[4517],3624,4606,13716,4976,{0},0, evict first: 1347, live active/inactive totals: 9055/28269
memory-pressure: found no pages to evict
memory-pressure: free memory after OOM eviction is 49MB
…
memory-pressure: pausing for 8s after OOM mem signal
[00028.317] 02811:03481> [fshost] INFO: [admin-server.cc(33)] received shutdown command over admin interface
[00028.317] 02811:03481> [fshost] INFO: [fs-manager.cc(281)] filesystem shutdown initiated
[00028.317] 02811:38032> [fshost] INFO: [fs-manager.cc(310)] Shutting down /data
[00028.318] 12900:12902> [minfs] INFO: [minfs.cc(1471)] Shutting down
[00028.340] 12900:12902> [minfs] WARNING: [src/storage/minfs/bin/main.cc(53)] Unmounted
[00028.341] 02811:03481> [fshost] INFO: [admin-server.cc(39)] shutdown complete
[00028.342] 02811:02813> [fshost] INFO: [main.cc(309)] terminating
[00028.342] 02687:02689> [driver_manager.cm] INFO: [suspend_handler.cc(205)] Successfully waited for VFS exit completion
memory-pressure: rebooting due to OOM
memory-pressure: stowing crashlog
ZIRCON REBOOT REASON (OOM)
Shutting down debuglog
platform_halt suggested_action 1 reason 3
Rebooting...

Signals userspace clients with specified memory pressure level. Clients can use this
command to test their response to memory pressure. Does not affect the real memory
pressure level on the system, or trigger any kernel reclamation tasks.
Positional Arguments:
  level             memory pressure level. Can be CRITICAL, WARNING or NORMAL.

[00213.059579][26701][26703][memory_monitor] INFO: [pressure_notifier.cc:106] Simulating memory pressure level WARNING