From: Tejun Heo <tj@kernel.org>
To: axboe@kernel.dk, vgoyal@redhat.com
Cc: ctalbott@google.com, rni@google.com,
linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>
Subject: [PATCH 33/36] block: add io_context->active_ref
Date: Tue, 21 Feb 2012 17:47:00 -0800 [thread overview]
Message-ID: <1329875223-5102-34-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1329875223-5102-1-git-send-email-tj@kernel.org>
Currently ioc->nr_tasks is used to decide two things - whether an ioc
is done issuing IOs and whether it's shared by multiple tasks. This
patch separate out the first into ioc->active_ref, which is acquired
and released using {get|put}_io_context_active() respectively.
This will be used to associate bio's with a given task. This patch
doesn't introduce any visible behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
block/blk-ioc.c | 36 +++++++++++++++++++++++++-----------
block/cfq-iosched.c | 4 ++--
include/linux/iocontext.h | 22 ++++++++++++++++++++--
3 files changed, 47 insertions(+), 15 deletions(-)
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 1092874..439ec21 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -149,20 +149,20 @@ void put_io_context(struct io_context *ioc)
}
EXPORT_SYMBOL(put_io_context);
-/* Called by the exiting task */
-void exit_io_context(struct task_struct *task)
+/**
+ * put_io_context_active - put active reference on ioc
+ * @ioc: ioc of interest
+ *
+ * Undo get_io_context_active(). If active reference reaches zero after
+ * put, @ioc can never issue further IOs and ioscheds are notified.
+ */
+void put_io_context_active(struct io_context *ioc)
{
- struct io_context *ioc;
- struct io_cq *icq;
struct hlist_node *n;
unsigned long flags;
+ struct io_cq *icq;
- task_lock(task);
- ioc = task->io_context;
- task->io_context = NULL;
- task_unlock(task);
-
- if (!atomic_dec_and_test(&ioc->nr_tasks)) {
+ if (!atomic_dec_and_test(&ioc->active_ref)) {
put_io_context(ioc);
return;
}
@@ -191,6 +191,20 @@ retry:
put_io_context(ioc);
}
+/* Called by the exiting task */
+void exit_io_context(struct task_struct *task)
+{
+ struct io_context *ioc;
+
+ task_lock(task);
+ ioc = task->io_context;
+ task->io_context = NULL;
+ task_unlock(task);
+
+ atomic_dec(&ioc->nr_tasks);
+ put_io_context_active(ioc);
+}
+
/**
* ioc_clear_queue - break any ioc association with the specified queue
* @q: request_queue being cleared
@@ -223,7 +237,7 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
/* initialize */
atomic_long_set(&ioc->refcount, 1);
- atomic_set(&ioc->nr_tasks, 1);
+ atomic_set(&ioc->active_ref, 1);
spin_lock_init(&ioc->lock);
INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);
INIT_HLIST_HEAD(&ioc->icq_list);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 42fa071..fc656b2 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1865,7 +1865,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
* task has exited, don't wait
*/
cic = cfqd->active_cic;
- if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks))
+ if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
return;
/*
@@ -2841,7 +2841,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
enable_idle = 0;
- else if (!atomic_read(&cic->icq.ioc->nr_tasks) ||
+ else if (!atomic_read(&cic->icq.ioc->active_ref) ||
!cfqd->cfq_slice_idle ||
(!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
enable_idle = 0;
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 81a8870..6f1a260 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -100,6 +100,7 @@ struct io_cq {
*/
struct io_context {
atomic_long_t refcount;
+ atomic_t active_ref;
atomic_t nr_tasks;
/* all the fields below are protected by this lock */
@@ -120,17 +121,34 @@ struct io_context {
struct work_struct release_work;
};
-static inline void ioc_task_link(struct io_context *ioc)
+/**
+ * get_io_context_active - get active reference on ioc
+ * @ioc: ioc of interest
+ *
+ * Only iocs with active reference can issue new IOs. This function
+ * acquires an active reference on @ioc. The caller must already have an
+ * active reference on @ioc.
+ */
+static inline void get_io_context_active(struct io_context *ioc)
{
WARN_ON_ONCE(atomic_long_read(&ioc->refcount) <= 0);
- WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0);
+ WARN_ON_ONCE(atomic_read(&ioc->active_ref) <= 0);
atomic_long_inc(&ioc->refcount);
+ atomic_inc(&ioc->active_ref);
+}
+
+static inline void ioc_task_link(struct io_context *ioc)
+{
+ get_io_context_active(ioc);
+
+ WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0);
atomic_inc(&ioc->nr_tasks);
}
struct task_struct;
#ifdef CONFIG_BLOCK
void put_io_context(struct io_context *ioc);
+void put_io_context_active(struct io_context *ioc);
void exit_io_context(struct task_struct *task);
struct io_context *get_task_io_context(struct task_struct *task,
gfp_t gfp_flags, int node);
--
1.7.7.3
next prev parent reply other threads:[~2012-02-22 1:48 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-22 1:46 [PATCHSET] blkcg: accumulated blkcg updates Tejun Heo
2012-02-22 1:46 ` [PATCH 01/36] block: blk-throttle should be drained regardless of q->elevator Tejun Heo
2012-02-22 1:46 ` [PATCH 02/36] blkcg: make CONFIG_BLK_CGROUP bool Tejun Heo
2012-02-22 1:46 ` [PATCH 03/36] cfq: don't register propio policy if !CONFIG_CFQ_GROUP_IOSCHED Tejun Heo
2012-02-22 1:46 ` [PATCH 04/36] elevator: clear auxiliary data earlier during elevator switch Tejun Heo
2012-02-22 1:46 ` [PATCH 05/36] elevator: make elevator_init_fn() return 0/-errno Tejun Heo
2012-02-22 1:46 ` [PATCH 06/36] block: implement blk_queue_bypass_start/end() Tejun Heo
2012-02-22 1:46 ` [PATCH 07/36] block: extend queue bypassing to cover blkcg policies Tejun Heo
2012-02-22 1:46 ` [PATCH 08/36] blkcg: shoot down blkio_groups on elevator switch Tejun Heo
2012-02-22 1:46 ` [PATCH 09/36] blkcg: move rcu_read_lock() outside of blkio_group get functions Tejun Heo
2012-02-22 1:46 ` [PATCH 10/36] blkcg: update blkg get functions take blkio_cgroup as parameter Tejun Heo
2012-02-22 1:46 ` [PATCH 11/36] blkcg: use q and plid instead of opaque void * for blkio_group association Tejun Heo
2012-02-22 1:46 ` [PATCH 12/36] blkcg: add blkio_policy[] array and allow one policy per policy ID Tejun Heo
2012-02-22 1:46 ` [PATCH 13/36] blkcg: use the usual get blkg path for root blkio_group Tejun Heo
2012-02-22 1:46 ` [PATCH 14/36] blkcg: factor out blkio_group creation Tejun Heo
2012-02-22 1:46 ` [PATCH 15/36] blkcg: don't allow or retain configuration of missing devices Tejun Heo
2012-02-22 1:46 ` [PATCH 16/36] blkcg: kill blkio_policy_node Tejun Heo
2012-02-22 1:46 ` [PATCH 17/36] blkcg: kill the mind-bending blkg->dev Tejun Heo
2012-02-22 1:46 ` [PATCH 18/36] blkcg: let blkio_group point to blkio_cgroup directly Tejun Heo
2012-02-22 1:46 ` [PATCH 19/36] blkcg: add blkcg_{init|drain|exit}_queue() Tejun Heo
2012-02-22 1:46 ` [PATCH 20/36] blkcg: clear all request_queues on blkcg policy [un]registrations Tejun Heo
2012-02-22 1:46 ` [PATCH 21/36] blkcg: let blkcg core handle policy private data allocation Tejun Heo
2012-02-22 1:46 ` [PATCH 22/36] blkcg: move refcnt to blkcg core Tejun Heo
2012-02-22 1:46 ` [PATCH 23/36] blkcg: make blkg->pd an array and move configuration and stats into it Tejun Heo
2012-02-22 1:46 ` [PATCH 24/36] blkcg: don't use blkg->plid in stat related functions Tejun Heo
2012-02-22 1:46 ` [PATCH 25/36] blkcg: move per-queue blkg list heads and counters to queue and blkg Tejun Heo
2012-02-22 1:46 ` [PATCH 26/36] blkcg: let blkcg core manage per-queue blkg list and counter Tejun Heo
2012-02-22 1:46 ` [PATCH 27/36] blkcg: unify blkg's for blkcg policies Tejun Heo
2012-03-05 21:01 ` [PATCH UPDATED " Tejun Heo
2012-02-22 1:46 ` [PATCH 28/36] blkcg: use double locking instead of RCU for blkg synchronization Tejun Heo
2012-02-22 1:46 ` [PATCH 29/36] blkcg: drop unnecessary RCU locking Tejun Heo
2012-02-23 18:51 ` [PATCH UPDATED " Tejun Heo
2012-02-22 1:46 ` [PATCH 30/36] block: restructure get_request() Tejun Heo
2012-02-22 1:46 ` [PATCH 31/36] block: interface update for ioc/icq creation functions Tejun Heo
2012-02-22 1:46 ` [PATCH 32/36] block: ioc_task_link() can't fail Tejun Heo
2012-02-22 1:47 ` Tejun Heo [this message]
2012-02-22 18:47 ` [PATCH 33/36] block: add io_context->active_ref Vivek Goyal
2012-02-22 19:13 ` Tejun Heo
2012-02-23 18:20 ` Vivek Goyal
2012-02-22 1:47 ` [PATCH 34/36] block: implement bio_associate_current() Tejun Heo
2012-02-22 13:45 ` Jeff Moyer
2012-02-22 19:07 ` Tejun Heo
2012-02-22 19:33 ` Jeff Moyer
2012-02-22 19:37 ` Vivek Goyal
2012-02-22 19:41 ` Jeff Moyer
2012-02-22 1:47 ` [PATCH 35/36] block: make block cgroup policies follow bio task association Tejun Heo
2012-02-22 1:47 ` [PATCH 36/36] block: make blk-throttle preserve the issuing task on delayed bios Tejun Heo
2012-02-22 19:34 ` [PATCHSET] blkcg: accumulated blkcg updates Vivek Goyal
2012-02-22 22:04 ` Tejun Heo
2012-03-05 20:59 ` [PATCH 17.5] blkcg: skip blkg printing if q isn't associated with disk Tejun Heo
2012-03-05 21:07 ` [PATCHSET] blkcg: accumulated blkcg updates Tejun Heo
2012-03-05 21:08 ` Tejun Heo
2012-03-06 15:07 ` Vivek Goyal
2012-03-06 16:24 ` Vivek Goyal
2012-03-06 18:39 ` Vivek Goyal
2012-03-06 19:02 ` Vivek Goyal
2012-03-08 0:06 ` Tejun Heo
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