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Message-ID: <4A40C64E.8040305@cn.fujitsu.com>
Date: Tue, 23 Jun 2009 20:10:54 +0800
From: Gui Jianfeng <guijianfeng@...fujitsu.com>
To: Vivek Goyal <vgoyal@...hat.com>
CC: linux-kernel@...r.kernel.org,
containers@...ts.linux-foundation.org, dm-devel@...hat.com,
jens.axboe@...cle.com, nauman@...gle.com, dpshah@...gle.com,
lizf@...fujitsu.com, mikew@...gle.com, fchecconi@...il.com,
paolo.valente@...more.it, ryov@...inux.co.jp,
fernando@....ntt.co.jp, s-uchida@...jp.nec.com, taka@...inux.co.jp,
jmoyer@...hat.com, dhaval@...ux.vnet.ibm.com,
balbir@...ux.vnet.ibm.com, righi.andrea@...il.com,
m-ikeda@...jp.nec.com, jbaron@...hat.com, agk@...hat.com,
snitzer@...hat.com, akpm@...ux-foundation.org, peterz@...radead.org
Subject: Re: [PATCH 07/20] io-controller: Export disk time used and nr sectors
dipatched through cgroups
Vivek Goyal wrote:
...
> +
> +static int io_cgroup_disk_sectors_read(struct cgroup *cgroup,
> + struct cftype *cftype, struct seq_file *m)
> +{
> + struct io_cgroup *iocg;
> + struct io_group *iog;
> + struct hlist_node *n;
> +
> + if (!cgroup_lock_live_group(cgroup))
> + return -ENODEV;
> +
> + iocg = cgroup_to_io_cgroup(cgroup);
> +
> + spin_lock_irq(&iocg->lock);
It's better to make use of rcu_read_lock instead since it's
a read action.
Signed-off-by: Gui Jianfeng <guijianfeng@...fujitsu.com>
---
block/elevator-fq.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index 2ad40eb..d779282 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -1418,7 +1418,7 @@ static int io_cgroup_disk_time_read(struct cgroup *cgroup,
iocg = cgroup_to_io_cgroup(cgroup);
- spin_lock_irq(&iocg->lock);
+ rcu_read_lock();
hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
/*
* There might be groups which are not functional and
@@ -1430,7 +1430,7 @@ static int io_cgroup_disk_time_read(struct cgroup *cgroup,
iog->entity.total_service);
}
}
- spin_unlock_irq(&iocg->lock);
+ rcu_read_unlock();
cgroup_unlock();
return 0;
@@ -1448,7 +1448,7 @@ static int io_cgroup_disk_sectors_read(struct cgroup *cgroup,
iocg = cgroup_to_io_cgroup(cgroup);
- spin_lock_irq(&iocg->lock);
+ rcu_read_lock();
hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
/*
* There might be groups which are not functional and
@@ -1460,7 +1460,7 @@ static int io_cgroup_disk_sectors_read(struct cgroup *cgroup,
iog->entity.total_sector_service);
}
}
- spin_unlock_irq(&iocg->lock);
+ rcu_read_unlock();
cgroup_unlock();
return 0;
@@ -1478,7 +1478,7 @@ static int io_cgroup_disk_queue_read(struct cgroup *cgroup,
return -ENODEV;
iocg = cgroup_to_io_cgroup(cgroup);
- spin_lock_irq(&iocg->lock);
+ rcu_read_lock();
/* Loop through all the io groups and print statistics */
hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
/*
@@ -1491,7 +1491,7 @@ static int io_cgroup_disk_queue_read(struct cgroup *cgroup,
iog->queue_duration);
}
}
- spin_unlock_irq(&iocg->lock);
+ rcu_read_unlock();
cgroup_unlock();
return 0;
--
1.5.4.rc3
> + hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
> + /*
> + * There might be groups which are not functional and
> + * waiting to be reclaimed upon cgoup deletion.
> + */
> + if (iog->key) {
> + seq_printf(m, "%u %u %lu\n", MAJOR(iog->dev),
> + MINOR(iog->dev),
> + iog->entity.total_sector_service);
> + }
> + }
> + spin_unlock_irq(&iocg->lock);
> + cgroup_unlock();
> +
> + return 0;
> +}
> +
>
--
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