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

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

include/linux/init_task.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -171,6 +171,7 @@ extern struct group_info init_groups; 
		[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID),		\

		[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID),		\

		[PIDTYPE_SID]  = INIT_PID_LINK(PIDTYPE_SID),		\

		[PIDTYPE_SID]  = INIT_PID_LINK(PIDTYPE_SID),		\

	},								\

	},								\

	.dirties = INIT_PROP_LOCAL_SINGLE(dirties),			\

	INIT_TRACE_IRQFLAGS						\

	INIT_TRACE_IRQFLAGS						\

	INIT_LOCKDEP							\

	INIT_LOCKDEP							\

}

}

include/linux/sched.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -74,6 +74,7 @@ struct sched_param { 
#include <linux/pid.h>

#include <linux/pid.h>

#include <linux/percpu.h>

#include <linux/percpu.h>

#include <linux/topology.h>

#include <linux/topology.h>

#include <linux/proportions.h>

#include <linux/seccomp.h>

#include <linux/seccomp.h>

#include <linux/rcupdate.h>

#include <linux/rcupdate.h>

#include <linux/futex.h>

#include <linux/futex.h>
@@ -1149,6 +1150,7 @@ struct task_struct { 
#ifdef CONFIG_FAULT_INJECTION

#ifdef CONFIG_FAULT_INJECTION

	int make_it_fail;

	int make_it_fail;

#endif

#endif

	struct prop_local_single dirties;

};

};





/*

/*

kernel/fork.c

+10 −0
Original line number Original line Diff line number Diff line
@@ -107,6 +107,7 @@ static struct kmem_cache *mm_cachep; 




void free_task(struct task_struct *tsk)

void free_task(struct task_struct *tsk)

{

{

	prop_local_destroy_single(&tsk->dirties);

	free_thread_info(tsk->stack);

	free_thread_info(tsk->stack);

	rt_mutex_debug_task_free(tsk);

	rt_mutex_debug_task_free(tsk);

	free_task_struct(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 task_struct *tsk;

	struct thread_info *ti;

	struct thread_info *ti;

	int err;





	prepare_to_copy(orig);

	prepare_to_copy(orig);
@@ -178,6 +180,14 @@ static struct task_struct *dup_task_struct(struct task_struct *orig) 




	*tsk = *orig;

	*tsk = *orig;

	tsk->stack = ti;

	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);

	setup_thread_stack(tsk, orig);





#ifdef CONFIG_CC_STACKPROTECTOR

#ifdef CONFIG_CC_STACKPROTECTOR

mm/page-writeback.c

+49 −1
Original line number Original line Diff line number Diff line
@@ -118,6 +118,7 @@ static void background_writeout(unsigned long _min_pages); 
 *

 *

 */

 */

static struct prop_descriptor vm_completions;

static struct prop_descriptor vm_completions;

static struct prop_descriptor vm_dirties;





static unsigned long determine_dirtyable_memory(void);

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) {

	if (ret == 0 && write && vm_dirty_ratio != old_ratio) {

		int shift = calc_period_shift();

		int shift = calc_period_shift();

		prop_change_shift(&vm_completions, shift);

		prop_change_shift(&vm_completions, shift);

		prop_change_shift(&vm_dirties, shift);

	}

	}

	return ret;

	return ret;

}

}
@@ -159,6 +161,11 @@ static inline void __bdi_writeout_inc(struct backing_dev_info *bdi) 
	__prop_inc_percpu(&vm_completions, &bdi->completions);

	__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.

 * 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);

	*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

 * Work out the current dirty-memory clamping and background writeout

 * thresholds.

 * thresholds.
@@ -304,6 +342,7 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty, 




		*pbdi_dirty = bdi_dirty;

		*pbdi_dirty = bdi_dirty;

		clip_bdi_dirty_limit(bdi, dirty, pbdi_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();

	shift = calc_period_shift();

	prop_descriptor_init(&vm_completions, 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

 * If the mapping doesn't provide a set_page_dirty a_op, then

 * just fall through and assume that it wants buffer_heads.

 * 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);

	struct address_space *mapping = page_mapping(page);
@@ -1016,6 +1056,14 @@ int fastcall set_page_dirty(struct page *page) 
	}

	}

	return 0;

	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);

EXPORT_SYMBOL(set_page_dirty);





/*

/*

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