From dcc25ae76eb7b8ff883eaaab57e30e8f2f085be3 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 22 May 2015 18:23:22 -0400 Subject: writeback: move global_dirty_limit into wb_domain This patch is a part of the series to define wb_domain which represents a domain that wb's (bdi_writeback's) belong to and are measured against each other in. This will enable IO backpressure propagation for cgroup writeback. global_dirty_limit exists to regulate the global dirty threshold which is a property of the wb_domain. This patch moves hard_dirty_limit, dirty_lock, and update_time into wb_domain. This is pure reorganization and doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Jan Kara Cc: Wu Fengguang Cc: Greg Thelen Signed-off-by: Jens Axboe --- include/linux/writeback.h | 17 ++++++++++++++++- include/trace/events/writeback.h | 7 ++++--- 2 files changed, 20 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 3148db1296a2..5fdd4e1805e6 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -95,6 +95,8 @@ struct writeback_control { * dirtyable memory accordingly. */ struct wb_domain { + spinlock_t lock; + /* * Scale the writeback cache size proportional to the relative * writeout speed. @@ -115,6 +117,19 @@ struct wb_domain { struct fprop_global completions; struct timer_list period_timer; /* timer for aging of completions */ unsigned long period_time; + + /* + * The dirtyable memory and dirty threshold could be suddenly + * knocked down by a large amount (eg. on the startup of KVM in a + * swapless system). This may throw the system into deep dirty + * exceeded state and throttle heavy/light dirtiers alike. To + * retain good responsiveness, maintain global_dirty_limit for + * tracking slowly down to the knocked down dirty threshold. + * + * Both fields are protected by ->lock. + */ + unsigned long dirty_limit_tstamp; + unsigned long dirty_limit; }; /* @@ -153,7 +168,7 @@ void throttle_vm_writeout(gfp_t gfp_mask); bool zone_dirty_ok(struct zone *zone); int wb_domain_init(struct wb_domain *dom, gfp_t gfp); -extern unsigned long global_dirty_limit; +extern struct wb_domain global_wb_domain; /* These are exported to sysctl. */ extern int dirty_background_ratio; diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 9b876f6cc81a..bec69995968f 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -361,7 +361,7 @@ TRACE_EVENT(global_dirty_state, __entry->nr_written = global_page_state(NR_WRITTEN); __entry->background_thresh = background_thresh; __entry->dirty_thresh = dirty_thresh; - __entry->dirty_limit = global_dirty_limit; + __entry->dirty_limit = global_wb_domain.dirty_limit; ), TP_printk("dirty=%lu writeback=%lu unstable=%lu " @@ -463,8 +463,9 @@ TRACE_EVENT(balance_dirty_pages, unsigned long freerun = (thresh + bg_thresh) / 2; strlcpy(__entry->bdi, dev_name(bdi->dev), 32); - __entry->limit = global_dirty_limit; - __entry->setpoint = (global_dirty_limit + freerun) / 2; + __entry->limit = global_wb_domain.dirty_limit; + __entry->setpoint = (global_wb_domain.dirty_limit + + freerun) / 2; __entry->dirty = dirty; __entry->bdi_setpoint = __entry->setpoint * bdi_thresh / (thresh + 1); -- cgit v1.2.3