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Message-ID: <20120214181245.GS12117@google.com>
Date: Tue, 14 Feb 2012 10:12:45 -0800
From: Tejun Heo <tj@...nel.org>
To: Jens Axboe <axboe@...nel.dk>, ShaohuaLishli@...nel.org
Cc: Vivek Goyal <vgoyal@...hat.com>,
lkml <linux-kernel@...r.kernel.org>,
Knut Petersen <Knut_Petersen@...nline.de>, mroos@...ux.ee,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH block/for-linus 1/3] block: replace icq->changed with
icq->flags
icq->changed was used for ICQ_*_CHANGED bits. Rename it to flags and
access it under ioc->lock instead of using atomic bitops.
ioc_get_changed() is added so that the changed part can be fetched and
cleared as before.
icq->flags will be used to carry other flags.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
Jens, these three patches are to fix the swap heavy workload
regression reported by Shaohua.
Shaohua, I ended up changing the second patch, which shouldn't change
anything but it would be great if you can verify this series once
more.
Thank you!
block/blk-ioc.c | 30 ++++++++++++++++++++++++++----
block/cfq-iosched.c | 12 ++++++------
include/linux/iocontext.h | 9 ++++++---
3 files changed, 38 insertions(+), 13 deletions(-)
Index: work/block/blk-ioc.c
===================================================================
--- work.orig/block/blk-ioc.c
+++ work/block/blk-ioc.c
@@ -363,13 +363,13 @@ struct io_cq *ioc_create_icq(struct requ
return icq;
}
-void ioc_set_changed(struct io_context *ioc, int which)
+void ioc_set_icq_flags(struct io_context *ioc, unsigned int flags)
{
struct io_cq *icq;
struct hlist_node *n;
hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node)
- set_bit(which, &icq->changed);
+ icq->flags |= flags;
}
/**
@@ -387,7 +387,7 @@ void ioc_ioprio_changed(struct io_contex
spin_lock_irqsave(&ioc->lock, flags);
ioc->ioprio = ioprio;
- ioc_set_changed(ioc, ICQ_IOPRIO_CHANGED);
+ ioc_set_icq_flags(ioc, ICQ_IOPRIO_CHANGED);
spin_unlock_irqrestore(&ioc->lock, flags);
}
@@ -404,11 +404,33 @@ void ioc_cgroup_changed(struct io_contex
unsigned long flags;
spin_lock_irqsave(&ioc->lock, flags);
- ioc_set_changed(ioc, ICQ_CGROUP_CHANGED);
+ ioc_set_icq_flags(ioc, ICQ_CGROUP_CHANGED);
spin_unlock_irqrestore(&ioc->lock, flags);
}
EXPORT_SYMBOL(ioc_cgroup_changed);
+/**
+ * icq_get_changed - fetch and clear icq changed mask
+ * @icq: icq of interest
+ *
+ * Fetch and clear ICQ_*_CHANGED bits from @icq. Grabs and releases
+ * @icq->ioc->lock.
+ */
+unsigned icq_get_changed(struct io_cq *icq)
+{
+ unsigned int changed = 0;
+ unsigned long flags;
+
+ if (unlikely(icq->flags & ICQ_CHANGED_MASK)) {
+ spin_lock_irqsave(&icq->ioc->lock, flags);
+ changed = icq->flags & ICQ_CHANGED_MASK;
+ icq->flags &= ~ICQ_CHANGED_MASK;
+ spin_unlock_irqrestore(&icq->ioc->lock, flags);
+ }
+ return changed;
+}
+EXPORT_SYMBOL(icq_get_changed);
+
static int __init blk_ioc_init(void)
{
iocontext_cachep = kmem_cache_create("blkdev_ioc",
Index: work/block/cfq-iosched.c
===================================================================
--- work.orig/block/cfq-iosched.c
+++ work/block/cfq-iosched.c
@@ -3470,20 +3470,20 @@ cfq_set_request(struct request_queue *q,
const int rw = rq_data_dir(rq);
const bool is_sync = rq_is_sync(rq);
struct cfq_queue *cfqq;
+ unsigned int changed;
might_sleep_if(gfp_mask & __GFP_WAIT);
spin_lock_irq(q->queue_lock);
/* handle changed notifications */
- if (unlikely(cic->icq.changed)) {
- if (test_and_clear_bit(ICQ_IOPRIO_CHANGED, &cic->icq.changed))
- changed_ioprio(cic);
+ changed = icq_get_changed(&cic->icq);
+ if (unlikely(changed & ICQ_IOPRIO_CHANGED))
+ changed_ioprio(cic);
#ifdef CONFIG_CFQ_GROUP_IOSCHED
- if (test_and_clear_bit(ICQ_CGROUP_CHANGED, &cic->icq.changed))
- changed_cgroup(cic);
+ if (unlikely(changed & ICQ_CGROUP_CHANGED))
+ changed_cgroup(cic);
#endif
- }
new_queue:
cfqq = cic_to_cfqq(cic, is_sync);
Index: work/include/linux/iocontext.h
===================================================================
--- work.orig/include/linux/iocontext.h
+++ work/include/linux/iocontext.h
@@ -6,8 +6,10 @@
#include <linux/workqueue.h>
enum {
- ICQ_IOPRIO_CHANGED,
- ICQ_CGROUP_CHANGED,
+ ICQ_IOPRIO_CHANGED = 1 << 0,
+ ICQ_CGROUP_CHANGED = 1 << 1,
+
+ ICQ_CHANGED_MASK = ICQ_IOPRIO_CHANGED | ICQ_CGROUP_CHANGED,
};
/*
@@ -88,7 +90,7 @@ struct io_cq {
struct rcu_head __rcu_head;
};
- unsigned long changed;
+ unsigned int flags;
};
/*
@@ -139,6 +141,7 @@ struct io_context *get_task_io_context(s
gfp_t gfp_flags, int node);
void ioc_ioprio_changed(struct io_context *ioc, int ioprio);
void ioc_cgroup_changed(struct io_context *ioc);
+unsigned int icq_get_changed(struct io_cq *icq);
#else
struct io_context;
static inline void put_io_context(struct io_context *ioc) { }
--
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