1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2019 Intel Corporation
*/
#include <linux/slab.h>
#include <linux/workqueue.h>
#include "i915_active.h"
#include "i915_gem_context.h"
#include "i915_gem_object.h"
#include "i915_globals.h"
#include "i915_request.h"
#include "i915_scheduler.h"
#include "i915_vma.h"
static LIST_HEAD(globals);
void __init i915_global_register(struct i915_global *global)
{
GEM_BUG_ON(!global->shrink);
GEM_BUG_ON(!global->exit);
list_add_tail(&global->link, &globals);
}
static void __i915_globals_cleanup(void)
{
struct i915_global *global, *next;
list_for_each_entry_safe_reverse(global, next, &globals, link)
global->exit();
}
static __initconst int (* const initfn[])(void) = {
i915_global_active_init,
i915_global_context_init,
i915_global_objects_init,
i915_global_request_init,
i915_global_scheduler_init,
i915_global_vma_init,
};
int __init i915_globals_init(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(initfn); i++) {
int err;
err = initfn[i]();
if (err) {
__i915_globals_cleanup();
return err;
}
}
return 0;
}
static void i915_globals_shrink(void)
{
struct i915_global *global;
/*
* kmem_cache_shrink() discards empty slabs and reorders partially
* filled slabs to prioritise allocating from the mostly full slabs,
* with the aim of reducing fragmentation.
*/
list_for_each_entry(global, &globals, link)
global->shrink();
}
static atomic_t active;
static atomic_t epoch;
struct park_work {
struct rcu_work work;
int epoch;
};
static void __i915_globals_park(struct work_struct *work)
{
struct park_work *wrk = container_of(work, typeof(*wrk), work.work);
/* Confirm nothing woke up in the last grace period */
if (wrk->epoch == atomic_read(&epoch))
i915_globals_shrink();
kfree(wrk);
}
void i915_globals_park(void)
{
struct park_work *wrk;
/*
* Defer shrinking the global slab caches (and other work) until
* after a RCU grace period has completed with no activity. This
* is to try and reduce the latency impact on the consumers caused
* by us shrinking the caches the same time as they are trying to
* allocate, with the assumption being that if we idle long enough
* for an RCU grace period to elapse since the last use, it is likely
* to be longer until we need the caches again.
*/
if (!atomic_dec_and_test(&active))
return;
wrk = kmalloc(sizeof(*wrk), GFP_KERNEL);
if (!wrk)
return;
wrk->epoch = atomic_inc_return(&epoch);
INIT_RCU_WORK(&wrk->work, __i915_globals_park);
queue_rcu_work(system_wq, &wrk->work);
}
void i915_globals_unpark(void)
{
atomic_inc(&epoch);
atomic_inc(&active);
}
void __exit i915_globals_exit(void)
{
/* Flush any residual park_work */
rcu_barrier();
flush_scheduled_work();
__i915_globals_cleanup();
/* And ensure that our DESTROY_BY_RCU slabs are truly destroyed */
rcu_barrier();
}
|
