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[/] [test_project/] [trunk/] [linux_sd_driver/] [mm/] [thrash.c] - Blame information for rev 82

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/*
 * 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.cs.wm.edu/~sjiang/token.pdf
 *
 * 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>
 
static DEFINE_SPINLOCK(swap_token_lock);
struct mm_struct *swap_token_mm;
static unsigned int global_faults;
 
void grab_swap_token(void)
{
        int current_interval;
 
        global_faults++;
 
        current_interval = global_faults - current->mm->faultstamp;
 
        if (!spin_trylock(&swap_token_lock))
                return;
 
        /* First come first served */
        if (swap_token_mm == NULL) {
                current->mm->token_priority = current->mm->token_priority + 2;
                swap_token_mm = current->mm;
                goto out;
        }
 
        if (current->mm != swap_token_mm) {
                if (current_interval < current->mm->last_interval)
                        current->mm->token_priority++;
                else {
                        if (likely(current->mm->token_priority > 0))
                                current->mm->token_priority--;
                }
                /* Check if we deserve the token */
                if (current->mm->token_priority >
                                swap_token_mm->token_priority) {
                        current->mm->token_priority += 2;
                        swap_token_mm = current->mm;
                }
        } else {
                /* Token holder came in again! */
                current->mm->token_priority += 2;
        }
 
out:
        current->mm->faultstamp = global_faults;
        current->mm->last_interval = current_interval;
        spin_unlock(&swap_token_lock);
return;
}
 
/* Called on process exit. */
void __put_swap_token(struct mm_struct *mm)
{
        spin_lock(&swap_token_lock);
        if (likely(mm == swap_token_mm))
                swap_token_mm = NULL;
        spin_unlock(&swap_token_lock);
}

Line No.	Rev	Author	Line
1	62	marcus.erl	`/*`
2			`* mm/thrash.c`
3			`*`
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.`
7			`*`
8			`* Simple token based thrashing protection, using the algorithm`
9			`* described in: http://www.cs.wm.edu/~sjiang/token.pdf`
10			`*`
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.`
18			`*/`
19
20			`#include <linux/jiffies.h>`
21			`#include <linux/mm.h>`
22			`#include <linux/sched.h>`
23			`#include <linux/swap.h>`
24
25			`static DEFINE_SPINLOCK(swap_token_lock);`
26			`struct mm_struct *swap_token_mm;`
27			`static unsigned int global_faults;`
28
29			`void grab_swap_token(void)`
30			`{`
31			`int current_interval;`
32
33			`global_faults++;`
34
35			`current_interval = global_faults - current->mm->faultstamp;`
36
37			`if (!spin_trylock(&swap_token_lock))`
38			`return;`
39
40			`/* First come first served */`
41			`if (swap_token_mm == NULL) {`
42			`current->mm->token_priority = current->mm->token_priority + 2;`
43			`swap_token_mm = current->mm;`
44			`goto out;`
45			`}`
46
47			`if (current->mm != swap_token_mm) {`
48			`if (current_interval < current->mm->last_interval)`
49			`current->mm->token_priority++;`
50			`else {`
51			`if (likely(current->mm->token_priority > 0))`
52			`current->mm->token_priority--;`
53			`}`
54			`/* Check if we deserve the token */`
55			`if (current->mm->token_priority >`
56			`swap_token_mm->token_priority) {`
57			`current->mm->token_priority += 2;`
58			`swap_token_mm = current->mm;`
59			`}`
60			`} else {`
61			`/* Token holder came in again! */`
62			`current->mm->token_priority += 2;`
63			`}`
64
65			`out:`
66			`current->mm->faultstamp = global_faults;`
67			`current->mm->last_interval = current_interval;`
68			`spin_unlock(&swap_token_lock);`
69			`return;`
70			`}`
71
72			`/* Called on process exit. */`
73			`void __put_swap_token(struct mm_struct *mm)`
74			`{`
75			`spin_lock(&swap_token_lock);`
76			`if (likely(mm == swap_token_mm))`
77			`swap_token_mm = NULL;`
78			`spin_unlock(&swap_token_lock);`
79			`}`

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[/] [test_project/] [trunk/] [linux_sd_driver/] [mm/] [thrash.c] - Blame information for rev 82