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 approached appear quite similar. Signed-off-by: Peter Zijlstra --- include/linux/sched.h | 2 + kernel/exit.c | 1 kernel/fork.c | 8 +++++++ mm/page-writeback.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++- 4 files changed, 66 insertions(+), 1 deletion(-) Index: linux-2.6/include/linux/sched.h =================================================================== --- linux-2.6.orig/include/linux/sched.h +++ linux-2.6/include/linux/sched.h @@ -86,6 +86,7 @@ struct sched_param { #include #include #include +#include #include @@ -1188,6 +1189,7 @@ struct task_struct { #ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif + struct prop_local_single dirties; }; /* Index: linux-2.6/kernel/exit.c =================================================================== --- linux-2.6.orig/kernel/exit.c +++ linux-2.6/kernel/exit.c @@ -161,6 +161,7 @@ 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 +++ linux-2.6/kernel/fork.c @@ -163,6 +163,7 @@ static struct task_struct *dup_task_stru { struct task_struct *tsk; struct thread_info *ti; + int err; prepare_to_copy(orig); @@ -176,6 +177,13 @@ static struct task_struct *dup_task_stru return NULL; } + err = prop_local_init(&tsk->dirties); + if (err) { + free_thread_info(ti); + free_task_struct(tsk); + return NULL; + } + *tsk = *orig; tsk->stack = ti; setup_thread_stack(tsk, orig); Index: linux-2.6/mm/page-writeback.c =================================================================== --- linux-2.6.orig/mm/page-writeback.c +++ linux-2.6/mm/page-writeback.c @@ -118,6 +118,7 @@ static void background_writeout(unsigned * */ 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(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. */ @@ -201,6 +213,38 @@ clip_bdi_dirty_limit(struct backing_dev_ *pbdi_dirty = min(*pbdi_dirty, avail_dirty); } +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); +} + +/* + * 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) + dirty = *pdirty/2; + + *pdirty = dirty; +} + /* * Work out the current dirty-memory clamping and background writeout * thresholds. @@ -307,6 +351,7 @@ get_dirty_limits(long *pbackground, long *pbdi_dirty = bdi_dirty; clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty); + task_dirty_limit(current, pbdi_dirty); } } @@ -728,6 +773,7 @@ void __init page_writeback_init(void) shift = calc_period_shift(); prop_descriptor_init(&vm_completions, shift); + prop_descriptor_init(&vm_dirties, shift); } /** @@ -1006,7 +1052,7 @@ 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); @@ -1024,6 +1070,14 @@ 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); /* -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/