[PATCH 15/15] mm: dirty balancing for tasks
From: Peter Zijlstra
Date: Thu May 10 2007 - 06:14:35 EST
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.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
include/linux/sched.h | 2 +
kernel/exit.c | 1
kernel/fork.c | 1
mm/page-writeback.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 63 insertions(+), 1 deletion(-)
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h 2007-05-10 11:06:12.000000000 +0200
+++ linux-2.6/include/linux/sched.h 2007-05-10 11:48:20.000000000 +0200
@@ -83,6 +83,7 @@ struct sched_param {
#include <linux/timer.h>
#include <linux/hrtimer.h>
#include <linux/task_io_accounting.h>
+#include <linux/proportions.h>
#include <asm/processor.h>
@@ -1092,6 +1093,7 @@ struct task_struct {
#ifdef CONFIG_FAULT_INJECTION
int make_it_fail;
#endif
+ struct prop_local dirties;
};
static inline pid_t process_group(struct task_struct *tsk)
Index: linux-2.6/kernel/exit.c
===================================================================
--- linux-2.6.orig/kernel/exit.c 2007-05-10 11:06:12.000000000 +0200
+++ linux-2.6/kernel/exit.c 2007-05-10 11:48:20.000000000 +0200
@@ -160,6 +160,7 @@ repeat:
ptrace_unlink(p);
BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
__exit_signal(p);
+ prop_local_destroy(&p->dirties);
/*
* If we are the last non-leader member of the thread
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c 2007-05-10 11:06:12.000000000 +0200
+++ linux-2.6/kernel/fork.c 2007-05-10 11:48:20.000000000 +0200
@@ -191,6 +191,7 @@ static struct task_struct *dup_task_stru
tsk->btrace_seq = 0;
#endif
tsk->splice_pipe = NULL;
+ prop_local_init(&tsk->dirties);
return tsk;
}
Index: linux-2.6/mm/page-writeback.c
===================================================================
--- linux-2.6.orig/mm/page-writeback.c 2007-05-10 11:06:12.000000000 +0200
+++ linux-2.6/mm/page-writeback.c 2007-05-10 11:54:56.000000000 +0200
@@ -118,6 +118,7 @@ static void background_writeout(unsigned
*
*/
struct prop_descriptor vm_completions;
+struct prop_descriptor vm_dirties;
static unsigned long determine_dirtyable_memory(void);
@@ -146,6 +147,7 @@ int dirty_ratio_handler(ctl_table *table
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;
}
@@ -161,6 +163,16 @@ static void __bdi_writeout_inc(struct ba
prop_put_global(&vm_completions, pg);
}
+static void task_dirty_inc(struct task_struct *tsk)
+{
+ unsigned long flags;
+ struct prop_global *pg = prop_get_global(&vm_dirties);
+ local_irq_save(flags);
+ __prop_inc(pg, &tsk->dirties);
+ local_irq_restore(flags);
+ prop_put_global(&vm_dirties, pg);
+}
+
/*
* Obtain an accurate fraction of the BDI's portion.
*/
@@ -177,6 +189,14 @@ void bdi_writeout_fraction(struct backin
}
}
+void task_dirties_fraction(struct task_struct *tsk,
+ long *numerator, long *denominator)
+{
+ struct prop_global *pg = prop_get_global(&vm_dirties);
+ prop_fraction(pg, &tsk->dirties, numerator, denominator);
+ prop_put_global(&vm_dirties, pg);
+}
+
/*
* Work out the current dirty-memory clamping and background writeout
* thresholds.
@@ -310,6 +330,33 @@ clip_bdi_dirty_limit(struct backing_dev_
}
/*
+ * scale the dirty limit
+ *
+ * task specific dirty limit:
+ *
+ * dirty -= (dirty/2) * p_{t}
+ */
+void task_dirty_limit(struct task_struct *tsk, long *pdirty)
+{
+ long numerator, denominator;
+ long dirty = *pdirty;
+ long long inv = dirty >> 1;
+
+ task_dirties_fraction(tsk, &numerator, &denominator);
+ inv *= numerator;
+ do_div(inv, denominator);
+
+ dirty -= inv;
+ if (dirty < *pdirty/2) {
+ printk("odd limit: %ld %ld %ld\n",
+ *pdirty, dirty, (long)inv);
+ dirty = *pdirty/2;
+ }
+
+ *pdirty = dirty;
+}
+
+/*
* balance_dirty_pages() must be called by processes which are generating dirty
* data. It looks at the number of dirty pages in the machine and will force
* the caller to perform writeback if the system is over `vm_dirty_ratio'.
@@ -340,6 +387,7 @@ static void balance_dirty_pages(struct a
get_dirty_limits(&background_thresh, &dirty_thresh,
&bdi_thresh, bdi);
clip_bdi_dirty_limit(bdi, dirty_thresh, &bdi_thresh);
+ task_dirty_limit(current, &bdi_thresh);
bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
@@ -360,6 +408,7 @@ static void balance_dirty_pages(struct a
get_dirty_limits(&background_thresh, &dirty_thresh,
&bdi_thresh, bdi);
clip_bdi_dirty_limit(bdi, dirty_thresh, &bdi_thresh);
+ task_dirty_limit(current, &bdi_thresh);
/*
* In order to avoid the stacked BDI deadlock we need
@@ -732,6 +781,7 @@ void __init page_writeback_init(void)
shift = calc_period_shift();
prop_descriptor_init(&vm_completions, shift);
+ prop_descriptor_init(&vm_dirties, shift);
}
/**
@@ -1009,7 +1059,7 @@ 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);
@@ -1027,6 +1077,14 @@ int fastcall set_page_dirty(struct 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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