| /* |
| * mm/thrash.c |
| * |
| * Copyright (C) 2004, Red Hat, Inc. |
| * Copyright (C) 2004, Rik van Riel <riel@redhat.com> |
| * Released under the GPL, see the file COPYING for details. |
| * |
| * Simple token based thrashing protection, using the algorithm |
| * described in: http://www.cse.ohio-state.edu/hpcs/WWW/HTML/publications/abs05-1.html |
| * |
| * Sep 2006, Ashwin Chaugule <ashwin.chaugule@celunite.com> |
| * Improved algorithm to pass token: |
| * Each task has a priority which is incremented if it contended |
| * for the token in an interval less than its previous attempt. |
| * If the token is acquired, that task's priority is boosted to prevent |
| * the token from bouncing around too often and to let the task make |
| * some progress in its execution. |
| */ |
| |
| #include <linux/jiffies.h> |
| #include <linux/mm.h> |
| #include <linux/sched.h> |
| #include <linux/swap.h> |
| #include <linux/memcontrol.h> |
| |
| #include <trace/events/vmscan.h> |
| |
| #define TOKEN_AGING_INTERVAL (0xFF) |
| |
| static DEFINE_SPINLOCK(swap_token_lock); |
| struct mm_struct *swap_token_mm; |
| struct mem_cgroup *swap_token_memcg; |
| static unsigned int global_faults; |
| static unsigned int last_aging; |
| |
| #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
| static struct mem_cgroup *swap_token_memcg_from_mm(struct mm_struct *mm) |
| { |
| struct mem_cgroup *memcg; |
| |
| memcg = try_get_mem_cgroup_from_mm(mm); |
| if (memcg) |
| css_put(mem_cgroup_css(memcg)); |
| |
| return memcg; |
| } |
| #else |
| static struct mem_cgroup *swap_token_memcg_from_mm(struct mm_struct *mm) |
| { |
| return NULL; |
| } |
| #endif |
| |
| void grab_swap_token(struct mm_struct *mm) |
| { |
| int current_interval; |
| unsigned int old_prio = mm->token_priority; |
| |
| global_faults++; |
| |
| current_interval = global_faults - mm->faultstamp; |
| |
| if (!spin_trylock(&swap_token_lock)) |
| return; |
| |
| /* First come first served */ |
| if (!swap_token_mm) |
| goto replace_token; |
| |
| if ((global_faults - last_aging) > TOKEN_AGING_INTERVAL) { |
| swap_token_mm->token_priority /= 2; |
| last_aging = global_faults; |
| } |
| |
| if (mm == swap_token_mm) { |
| mm->token_priority += 2; |
| goto update_priority; |
| } |
| |
| if (current_interval < mm->last_interval) |
| mm->token_priority++; |
| else { |
| if (likely(mm->token_priority > 0)) |
| mm->token_priority--; |
| } |
| |
| /* Check if we deserve the token */ |
| if (mm->token_priority > swap_token_mm->token_priority) |
| goto replace_token; |
| |
| update_priority: |
| trace_update_swap_token_priority(mm, old_prio, swap_token_mm); |
| |
| out: |
| mm->faultstamp = global_faults; |
| mm->last_interval = current_interval; |
| spin_unlock(&swap_token_lock); |
| return; |
| |
| replace_token: |
| mm->token_priority += 2; |
| trace_replace_swap_token(swap_token_mm, mm); |
| swap_token_mm = mm; |
| swap_token_memcg = swap_token_memcg_from_mm(mm); |
| last_aging = global_faults; |
| goto out; |
| } |
| |
| /* Called on process exit. */ |
| void __put_swap_token(struct mm_struct *mm) |
| { |
| spin_lock(&swap_token_lock); |
| if (likely(mm == swap_token_mm)) { |
| trace_put_swap_token(swap_token_mm); |
| swap_token_mm = NULL; |
| swap_token_memcg = NULL; |
| } |
| spin_unlock(&swap_token_lock); |
| } |
| |
| static bool match_memcg(struct mem_cgroup *a, struct mem_cgroup *b) |
| { |
| if (!a) |
| return true; |
| if (!b) |
| return true; |
| if (a == b) |
| return true; |
| return false; |
| } |
| |
| void disable_swap_token(struct mem_cgroup *memcg) |
| { |
| /* memcg reclaim don't disable unrelated mm token. */ |
| if (match_memcg(memcg, swap_token_memcg)) { |
| spin_lock(&swap_token_lock); |
| if (match_memcg(memcg, swap_token_memcg)) { |
| trace_disable_swap_token(swap_token_mm); |
| swap_token_mm = NULL; |
| swap_token_memcg = NULL; |
| } |
| spin_unlock(&swap_token_lock); |
| } |
| } |