Commit 3e26c149 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds

mm: dirty balancing for tasks

Based on ideas of Andrew:
  http://marc.info/?l=linux-kernel&m=102912915020543&w=2

Scale the bdi dirty limit inversly with the tasks dirty rate.
This makes heavy writers have a lower dirty limit than the occasional writer.

Andrea proposed something similar:
  http://lwn.net/Articles/152277/

The main disadvantage to his patch is that he uses an unrelated quantity to
measure time, which leaves him with a workload dependant tunable. Other than
that the two approaches appear quite similar.

[akpm@linux-foundation.org: fix warning]
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 04fbfdc1
......@@ -171,6 +171,7 @@ extern struct group_info init_groups;
[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID), \
[PIDTYPE_SID] = INIT_PID_LINK(PIDTYPE_SID), \
}, \
.dirties = INIT_PROP_LOCAL_SINGLE(dirties), \
INIT_TRACE_IRQFLAGS \
INIT_LOCKDEP \
}
......
......@@ -74,6 +74,7 @@ struct sched_param {
#include <linux/pid.h>
#include <linux/percpu.h>
#include <linux/topology.h>
#include <linux/proportions.h>
#include <linux/seccomp.h>
#include <linux/rcupdate.h>
#include <linux/futex.h>
......@@ -1149,6 +1150,7 @@ struct task_struct {
#ifdef CONFIG_FAULT_INJECTION
int make_it_fail;
#endif
struct prop_local_single dirties;
};
/*
......
......@@ -107,6 +107,7 @@ static struct kmem_cache *mm_cachep;
void free_task(struct task_struct *tsk)
{
prop_local_destroy_single(&tsk->dirties);
free_thread_info(tsk->stack);
rt_mutex_debug_task_free(tsk);
free_task_struct(tsk);
......@@ -163,6 +164,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
int err;
prepare_to_copy(orig);
......@@ -178,6 +180,14 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
*tsk = *orig;
tsk->stack = ti;
err = prop_local_init_single(&tsk->dirties);
if (err) {
free_thread_info(ti);
free_task_struct(tsk);
return NULL;
}
setup_thread_stack(tsk, orig);
#ifdef CONFIG_CC_STACKPROTECTOR
......
......@@ -118,6 +118,7 @@ static void background_writeout(unsigned long _min_pages);
*
*/
static struct prop_descriptor vm_completions;
static struct prop_descriptor vm_dirties;
static unsigned long determine_dirtyable_memory(void);
......@@ -146,6 +147,7 @@ int dirty_ratio_handler(struct ctl_table *table, int write,
if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
int shift = calc_period_shift();
prop_change_shift(&vm_completions, shift);
prop_change_shift(&vm_dirties, shift);
}
return ret;
}
......@@ -159,6 +161,11 @@ static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
__prop_inc_percpu(&vm_completions, &bdi->completions);
}
static inline void task_dirty_inc(struct task_struct *tsk)
{
prop_inc_single(&vm_dirties, &tsk->dirties);
}
/*
* Obtain an accurate fraction of the BDI's portion.
*/
......@@ -198,6 +205,37 @@ clip_bdi_dirty_limit(struct backing_dev_info *bdi, long dirty, long *pbdi_dirty)
*pbdi_dirty = min(*pbdi_dirty, avail_dirty);
}
static inline void task_dirties_fraction(struct task_struct *tsk,
long *numerator, long *denominator)
{
prop_fraction_single(&vm_dirties, &tsk->dirties,
numerator, denominator);
}
/*
* scale the dirty limit
*
* task specific dirty limit:
*
* dirty -= (dirty/8) * p_{t}
*/
void task_dirty_limit(struct task_struct *tsk, long *pdirty)
{
long numerator, denominator;
long dirty = *pdirty;
u64 inv = dirty >> 3;
task_dirties_fraction(tsk, &numerator, &denominator);
inv *= numerator;
do_div(inv, denominator);
dirty -= inv;
if (dirty < *pdirty/2)
dirty = *pdirty/2;
*pdirty = dirty;
}
/*
* Work out the current dirty-memory clamping and background writeout
* thresholds.
......@@ -304,6 +342,7 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
*pbdi_dirty = bdi_dirty;
clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty);
task_dirty_limit(current, pbdi_dirty);
}
}
......@@ -720,6 +759,7 @@ void __init page_writeback_init(void)
shift = calc_period_shift();
prop_descriptor_init(&vm_completions, shift);
prop_descriptor_init(&vm_dirties, shift);
}
/**
......@@ -998,7 +1038,7 @@ EXPORT_SYMBOL(redirty_page_for_writepage);
* If the mapping doesn't provide a set_page_dirty a_op, then
* just fall through and assume that it wants buffer_heads.
*/
int fastcall set_page_dirty(struct page *page)
static int __set_page_dirty(struct page *page)
{
struct address_space *mapping = page_mapping(page);
......@@ -1016,6 +1056,14 @@ int fastcall set_page_dirty(struct page *page)
}
return 0;
}
int fastcall set_page_dirty(struct page *page)
{
int ret = __set_page_dirty(page);
if (ret)
task_dirty_inc(current);
return ret;
}
EXPORT_SYMBOL(set_page_dirty);
/*
......
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