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authorTejun Heo <tj@kernel.org>2015-05-22 18:23:22 -0400
committerJens Axboe <axboe@fb.com>2015-06-02 08:38:12 -0600
commitdcc25ae76eb7b8ff883eaaab57e30e8f2f085be3 (patch)
tree7fb1d01278ad2b16a1c21ead3e567a3bb7d00c25 /include/linux/writeback.h
parent380c27ca33ebecc9da35aa90c8b3a9154f90aac2 (diff)
downloadlwn-dcc25ae76eb7b8ff883eaaab57e30e8f2f085be3.tar.gz
lwn-dcc25ae76eb7b8ff883eaaab57e30e8f2f085be3.zip
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 <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/writeback.h')
-rw-r--r--include/linux/writeback.h17
1 files changed, 16 insertions, 1 deletions
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;