6cdf86511385b019619d2d12b119161ce5c91752
4 * Copyright (C) 2004, Red Hat, Inc.
5 * Copyright (C) 2004, Rik van Riel <riel@redhat.com>
6 * Released under the GPL, see the file COPYING for details.
8 * Simple token based thrashing protection, using the algorithm
9 * described in: http://www.cs.wm.edu/~sjiang/token.pdf
11 * Sep 2006, Ashwin Chaugule <ashwin.chaugule@celunite.com>
12 * Improved algorithm to pass token:
13 * Each task has a priority which is incremented if it contended
14 * for the token in an interval less than its previous attempt.
15 * If the token is acquired, that task's priority is boosted to prevent
16 * the token from bouncing around too often and to let the task make
17 * some progress in its execution.
20 #include <linux/jiffies.h>
22 #include <linux/sched.h>
23 #include <linux/swap.h>
24 #include <linux/memcontrol.h>
26 static DEFINE_SPINLOCK(swap_token_lock
);
27 struct mm_struct
*swap_token_mm
;
28 struct mem_cgroup
*swap_token_memcg
;
29 static unsigned int global_faults
;
31 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
32 static struct mem_cgroup
*swap_token_memcg_from_mm(struct mm_struct
*mm
)
34 struct mem_cgroup
*memcg
;
36 memcg
= try_get_mem_cgroup_from_mm(mm
);
38 css_put(mem_cgroup_css(memcg
));
43 static struct mem_cgroup
*swap_token_memcg_from_mm(struct mm_struct
*mm
)
49 void grab_swap_token(struct mm_struct
*mm
)
55 current_interval
= global_faults
- mm
->faultstamp
;
57 if (!spin_trylock(&swap_token_lock
))
60 /* First come first served */
64 if (mm
== swap_token_mm
) {
65 mm
->token_priority
+= 2;
69 if (current_interval
< mm
->last_interval
)
72 if (likely(mm
->token_priority
> 0))
76 /* Check if we deserve the token */
77 if (mm
->token_priority
> swap_token_mm
->token_priority
)
81 mm
->faultstamp
= global_faults
;
82 mm
->last_interval
= current_interval
;
83 spin_unlock(&swap_token_lock
);
87 mm
->token_priority
+= 2;
89 swap_token_memcg
= swap_token_memcg_from_mm(mm
);
93 /* Called on process exit. */
94 void __put_swap_token(struct mm_struct
*mm
)
96 spin_lock(&swap_token_lock
);
97 if (likely(mm
== swap_token_mm
)) {
99 swap_token_memcg
= NULL
;
101 spin_unlock(&swap_token_lock
);
104 static bool match_memcg(struct mem_cgroup
*a
, struct mem_cgroup
*b
)
115 void disable_swap_token(struct mem_cgroup
*memcg
)
117 /* memcg reclaim don't disable unrelated mm token. */
118 if (match_memcg(memcg
, swap_token_memcg
)) {
119 spin_lock(&swap_token_lock
);
120 if (match_memcg(memcg
, swap_token_memcg
)) {
121 swap_token_mm
= NULL
;
122 swap_token_memcg
= NULL
;
124 spin_unlock(&swap_token_lock
);
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