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[PATCH 05/12] inode: convert inode_stat.nr_unused to per-cpu counters

To: linux-fsdevel@xxxxxxxxxxxxxxx
Subject: [PATCH 05/12] inode: convert inode_stat.nr_unused to per-cpu counters
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Thu, 2 Jun 2011 17:01:00 +1000
Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <1306998067-27659-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1306998067-27659-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

Before we split up the inode_lru_lock, the unused inode counter
needs to be made independent of the global inode_lru_lock. Convert
it to per-cpu counters to do this.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/inode.c |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 0f7e88a..17fea5b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -95,6 +95,7 @@ EXPORT_SYMBOL(empty_aops);
 struct inodes_stat_t inodes_stat;
 
 static DEFINE_PER_CPU(unsigned int, nr_inodes);
+static DEFINE_PER_CPU(unsigned int, nr_unused);
 
 static struct kmem_cache *inode_cachep __read_mostly;
 
@@ -109,7 +110,11 @@ static int get_nr_inodes(void)
 
 static inline int get_nr_inodes_unused(void)
 {
-       return inodes_stat.nr_unused;
+       int i;
+       int sum = 0;
+       for_each_possible_cpu(i)
+               sum += per_cpu(nr_unused, i);
+       return sum < 0 ? 0 : sum;
 }
 
 int get_nr_dirty_inodes(void)
@@ -127,6 +132,7 @@ int proc_nr_inodes(ctl_table *table, int write,
                   void __user *buffer, size_t *lenp, loff_t *ppos)
 {
        inodes_stat.nr_inodes = get_nr_inodes();
+       inodes_stat.nr_unused = get_nr_inodes_unused();
        return proc_dointvec(table, write, buffer, lenp, ppos);
 }
 #endif
@@ -340,7 +346,7 @@ static void inode_lru_list_add(struct inode *inode)
        spin_lock(&inode_lru_lock);
        if (list_empty(&inode->i_lru)) {
                list_add(&inode->i_lru, &inode_lru);
-               inodes_stat.nr_unused++;
+               this_cpu_inc(nr_unused);
        }
        spin_unlock(&inode_lru_lock);
 }
@@ -350,7 +356,7 @@ static void inode_lru_list_del(struct inode *inode)
        spin_lock(&inode_lru_lock);
        if (!list_empty(&inode->i_lru)) {
                list_del_init(&inode->i_lru);
-               inodes_stat.nr_unused--;
+               this_cpu_dec(nr_unused);
        }
        spin_unlock(&inode_lru_lock);
 }
@@ -649,7 +655,7 @@ static void prune_icache(int nr_to_scan)
                    (inode->i_state & ~I_REFERENCED)) {
                        list_del_init(&inode->i_lru);
                        spin_unlock(&inode->i_lock);
-                       inodes_stat.nr_unused--;
+                       this_cpu_dec(nr_unused);
                        continue;
                }
 
@@ -686,7 +692,7 @@ static void prune_icache(int nr_to_scan)
                spin_unlock(&inode->i_lock);
 
                list_move(&inode->i_lru, &freeable);
-               inodes_stat.nr_unused--;
+               this_cpu_dec(nr_unused);
        }
        if (current_is_kswapd())
                __count_vm_events(KSWAPD_INODESTEAL, reap);
-- 
1.7.5.1

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