From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 6/6] mm: per device dirty threshold From: Peter Zijlstra In-Reply-To: References: <20070403144047.073283598@taijtu.programming.kicks-ass.net> <20070403144224.709586192@taijtu.programming.kicks-ass.net> <1175681794.6483.43.camel@twins> <1175684461.6483.64.camel@twins> <1175688356.6483.81.camel@twins> Content-Type: text/plain Date: Wed, 04 Apr 2007 14:43:37 +0200 Message-Id: <1175690617.6483.85.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Miklos Szeredi Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com List-ID: On Wed, 2007-04-04 at 14:32 +0200, Miklos Szeredi wrote: > > Preferably you'd want to be able to 'flush' the per cpu diffs or > > something like that in cases where thresh ~< NR_CPUS * stat_diff. > > > > How about something like this: > > Yes, maybe underscores and EXPORT_SYMBOLs are a bit excessive. probably, here is one that actually compiles and handles cpu hotplug; albeit a bit racy - which lock does exclude cpu hotplug these days? --- include/linux/backing-dev.h | 13 +++++++ mm/backing-dev.c | 79 ++++++++++++++++++++++++++++++++++++++++++++ mm/page-writeback.c | 4 ++ 3 files changed, 96 insertions(+) Index: linux-2.6/include/linux/backing-dev.h =================================================================== --- linux-2.6.orig/include/linux/backing-dev.h +++ linux-2.6/include/linux/backing-dev.h @@ -8,6 +8,7 @@ #ifndef _LINUX_BACKING_DEV_H #define _LINUX_BACKING_DEV_H +#include #include #include @@ -117,6 +118,13 @@ void mod_bdi_stat(struct backing_dev_inf void inc_bdi_stat(struct backing_dev_info *bdi, enum bdi_stat_item item); void dec_bdi_stat(struct backing_dev_info *bdi, enum bdi_stat_item item); +void bdi_flush_stat(struct backing_dev_info *bdi, enum bdi_stat_item item); +void bdi_flush_all(struct backing_dev_info *bdi); + +static inline unsigned long bdi_stat_delta(void) +{ + return 8UL * num_online_cpus() * ilog2(num_online_cpus()); +} #else /* CONFIG_SMP */ static inline void __mod_bdi_stat(struct backing_dev_info *bdi, @@ -142,6 +150,11 @@ static inline void __dec_bdi_stat(struct #define mod_bdi_stat __mod_bdi_stat #define inc_bdi_stat __inc_bdi_stat #define dec_bdi_stat __dec_bdi_stat + +#define bdi_flush_stat(bdi, item) do { } while (0) +#define bdi_flush_all(bdi) do { } while (0) + +#define bdi_stat_delta() 1UL #endif void bdi_stat_init(struct backing_dev_info *bdi); Index: linux-2.6/mm/backing-dev.c =================================================================== --- linux-2.6.orig/mm/backing-dev.c +++ linux-2.6/mm/backing-dev.c @@ -188,4 +188,83 @@ void dec_bdi_stat(struct backing_dev_inf local_irq_restore(flags); } EXPORT_SYMBOL(dec_bdi_stat); + +void ___bdi_flush_stat(struct backing_dev_info *bdi, enum bdi_stat_item item, + int cpu) +{ + struct bdi_per_cpu_data *pcd = &bdi->pcd[cpu]; + s8 *p = pcd->bdi_stat_diff + item; + + bdi_stat_add(*p, bdi, item); + *p = 0; +} + +struct bdi_flush_struct { + struct backing_dev_info *bdi; + enum bdi_stat_item item; +}; + +void __bdi_flush_stat(struct bdi_flush_struct *flush) +{ + unsigned long flags; + + local_irq_save(flags); + ___bdi_flush_stat(flush->bdi, flush->item, smp_processor_id()); + local_irq_restore(flags); +} + +void __bdi_flush_all(struct backing_dev_info *bdi) +{ + unsigned long flags; + int i, cpu; + + local_irq_save(flags); + cpu = smp_processor_id(); + for (i = 0; i < NR_BDI_STAT_ITEMS; i++) + ___bdi_flush_stat(bdi, i, cpu); + local_irq_restore(flags); +} + +void bdi_flush_stat(struct backing_dev_info *bdi, enum bdi_stat_item item) +{ + struct bdi_flush_struct flush = { + bdi, + item + }; + +#ifdef CONFIG_HOTPLUG_CPU + cpumask_t mask; + int cpu; + + cpus_complement(mask, cpu_online_map); + for_each_cpu_mask(cpu, mask) { + unsigned long flags; + + local_irq_save(flags); + ___bdi_flush_stat(bdi, item, cpu); + local_irq_restore(flags); + } +#endif + on_each_cpu((void (*)(void *))__bdi_flush_stat, &flush, 0, 1); +} + +void bdi_flush_all(struct backing_dev_info *bdi) +{ +#ifdef CONFIG_HOTPLUG_CPU + cpumask_t mask; + int cpu; + + cpus_complement(mask, cpu_online_map); + for_each_cpu_mask(cpu, mask) { + int i; + unsigned long flags; + + local_irq_save(flags); + for (i = 0; i < NR_BDI_STAT_ITEMS; i++) + ___bdi_flush_stat(bdi, i, cpu); + local_irq_restore(flags); + } +#endif + on_each_cpu((void (*)(void *))__bdi_flush_all, bdi, 0, 1); +} #endif Index: linux-2.6/mm/page-writeback.c =================================================================== --- linux-2.6.orig/mm/page-writeback.c +++ linux-2.6/mm/page-writeback.c @@ -345,6 +345,10 @@ static void balance_dirty_pages(struct a get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); + + if (bdi_thresh < bdi_stat_delta()) + bdi_flush_all(bdi); + bdi_nr_reclaimable = bdi_stat(bdi, BDI_DIRTY) + bdi_stat(bdi, BDI_UNSTABLE); if (bdi_nr_reclaimable + bdi_stat(bdi, BDI_WRITEBACK) <= -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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