diff options
| -rw-r--r-- | include/linux/sched.h | 13 | ||||
| -rw-r--r-- | include/linux/swap.h | 1 | ||||
| -rw-r--r-- | kernel/fork.c | 8 | ||||
| -rw-r--r-- | kernel/sysctl.c | 11 | ||||
| -rw-r--r-- | mm/thrash.c | 116 |
5 files changed, 63 insertions, 86 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index eafe4a7..cad6a16 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 e7c36ba..89f8a39 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 8cdd3e7..5678e6c 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 09e569f4..7abe970 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 f4c560b..19e428c 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); } |
