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-rw-r--r--include/linux/sched.h13
-rw-r--r--include/linux/swap.h1
-rw-r--r--kernel/fork.c8
-rw-r--r--kernel/sysctl.c11
-rw-r--r--mm/thrash.c116
5 files changed, 63 insertions, 86 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index eafe4a7b823..cad6a16260f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -344,9 +344,16 @@ struct mm_struct {
/* Architecture-specific MM context */
mm_context_t context;
- /* Token based thrashing protection. */
- unsigned long swap_token_time;
- char recent_pagein;
+ /* Swap token stuff */
+ /*
+ * Last value of global fault stamp as seen by this process.
+ * In other words, this value gives an indication of how long
+ * it has been since this task got the token.
+ * Look at mm/thrash.c
+ */
+ unsigned int faultstamp;
+ unsigned int token_priority;
+ unsigned int last_interval;
/* coredumping support */
int core_waiters;
diff --git a/include/linux/swap.h b/include/linux/swap.h
index e7c36ba2a2d..89f8a39773b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -259,7 +259,6 @@ extern spinlock_t swap_lock;
/* linux/mm/thrash.c */
extern struct mm_struct * swap_token_mm;
-extern unsigned long swap_token_default_timeout;
extern void grab_swap_token(void);
extern void __put_swap_token(struct mm_struct *);
diff --git a/kernel/fork.c b/kernel/fork.c
index 8cdd3e72ba5..5678e6c61ef 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -479,6 +479,10 @@ static struct mm_struct *dup_mm(struct task_struct *tsk)
memcpy(mm, oldmm, sizeof(*mm));
+ /* Initializing for Swap token stuff */
+ mm->token_priority = 0;
+ mm->last_interval = 0;
+
if (!mm_init(mm))
goto fail_nomem;
@@ -542,6 +546,10 @@ static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
goto fail_nomem;
good_mm:
+ /* Initializing for Swap token stuff */
+ mm->token_priority = 0;
+ mm->last_interval = 0;
+
tsk->mm = mm;
tsk->active_mm = mm;
return 0;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 09e569f4792..7abe9704e75 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -977,17 +977,6 @@ static ctl_table vm_table[] = {
.extra1 = &zero,
},
#endif
-#ifdef CONFIG_SWAP
- {
- .ctl_name = VM_SWAP_TOKEN_TIMEOUT,
- .procname = "swap_token_timeout",
- .data = &swap_token_default_timeout,
- .maxlen = sizeof(swap_token_default_timeout),
- .mode = 0644,
- .proc_handler = &proc_dointvec_jiffies,
- .strategy = &sysctl_jiffies,
- },
-#endif
#ifdef CONFIG_NUMA
{
.ctl_name = VM_ZONE_RECLAIM_MODE,
diff --git a/mm/thrash.c b/mm/thrash.c
index f4c560b4a2b..19e428ca8b0 100644
--- a/mm/thrash.c
+++ b/mm/thrash.c
@@ -7,100 +7,74 @@
*
* 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);
-static unsigned long swap_token_timeout;
-static unsigned long swap_token_check;
-struct mm_struct * swap_token_mm = &init_mm;
-
-#define SWAP_TOKEN_CHECK_INTERVAL (HZ * 2)
-#define SWAP_TOKEN_TIMEOUT (300 * HZ)
-/*
- * Currently disabled; Needs further code to work at HZ * 300.
- */
-unsigned long swap_token_default_timeout = SWAP_TOKEN_TIMEOUT;
-
-/*
- * Take the token away if the process had no page faults
- * in the last interval, or if it has held the token for
- * too long.
- */
-#define SWAP_TOKEN_ENOUGH_RSS 1
-#define SWAP_TOKEN_TIMED_OUT 2
-static int should_release_swap_token(struct mm_struct *mm)
-{
- int ret = 0;
- if (!mm->recent_pagein)
- ret = SWAP_TOKEN_ENOUGH_RSS;
- else if (time_after(jiffies, swap_token_timeout))
- ret = SWAP_TOKEN_TIMED_OUT;
- mm->recent_pagein = 0;
- return ret;
-}
+struct mm_struct *swap_token_mm;
+unsigned int global_faults;
-/*
- * Try to grab the swapout protection token. We only try to
- * grab it once every TOKEN_CHECK_INTERVAL, both to prevent
- * SMP lock contention and to check that the process that held
- * the token before is no longer thrashing.
- */
void grab_swap_token(void)
{
- struct mm_struct *mm;
- int reason;
+ int current_interval;
- /* We have the token. Let others know we still need it. */
- if (has_swap_token(current->mm)) {
- current->mm->recent_pagein = 1;
- if (unlikely(!swap_token_default_timeout))
- disable_swap_token();
- return;
- }
-
- if (time_after(jiffies, swap_token_check)) {
+ global_faults++;
- if (!swap_token_default_timeout) {
- swap_token_check = jiffies + SWAP_TOKEN_CHECK_INTERVAL;
- return;
- }
-
- /* ... or if we recently held the token. */
- if (time_before(jiffies, current->mm->swap_token_time))
- return;
+ current_interval = global_faults - current->mm->faultstamp;
- if (!spin_trylock(&swap_token_lock))
- return;
+ if (!spin_trylock(&swap_token_lock))
+ return;
- swap_token_check = jiffies + SWAP_TOKEN_CHECK_INTERVAL;
+ /* 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;
+ }
- mm = swap_token_mm;
- if ((reason = should_release_swap_token(mm))) {
- unsigned long eligible = jiffies;
- if (reason == SWAP_TOKEN_TIMED_OUT) {
- eligible += swap_token_default_timeout;
- }
- mm->swap_token_time = eligible;
- swap_token_timeout = jiffies + swap_token_default_timeout;
+ if (current->mm != swap_token_mm) {
+ if (current_interval < current->mm->last_interval)
+ current->mm->token_priority++;
+ else {
+ current->mm->token_priority--;
+ if (unlikely(current->mm->token_priority < 0))
+ current->mm->token_priority = 0;
+ }
+ /* 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;
}
- spin_unlock(&swap_token_lock);
+ } else {
+ /* Token holder came in again! */
+ current->mm->token_priority += 2;
}
- return;
+
+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)) {
- mm->swap_token_time = jiffies + SWAP_TOKEN_CHECK_INTERVAL;
- swap_token_mm = &init_mm;
- swap_token_check = jiffies;
- }
+ if (likely(mm == swap_token_mm))
+ swap_token_mm = NULL;
spin_unlock(&swap_token_lock);
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-04 11:09:30 +0000