On Mon, Aug 8, 2011 at 10:03 AM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> Before we split up the dcache_lru_lock, the unused dentry counter
> needs to be made independent of the global dcache_lru_lock. Convert
> it to per-cpu counters to do this.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> fs/dcache.c | 17 ++++++++++++++---
> 1 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index b05aac3..5e5208d 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -116,6 +116,7 @@ struct dentry_stat_t dentry_stat = {
> };
>
> static DEFINE_PER_CPU(unsigned int, nr_dentry);
> +static DEFINE_PER_CPU(unsigned int, nr_dentry_unused);
>
> #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
> static int get_nr_dentry(void)
> @@ -127,10 +128,20 @@ static int get_nr_dentry(void)
> return sum < 0 ? 0 : sum;
> }
>
> +static int get_nr_dentry_unused(void)
> +{
> + int i;
> + int sum = 0;
> + for_each_possible_cpu(i)
> + sum += per_cpu(nr_dentry_unused, i);
> + return sum < 0 ? 0 : sum;
> +}
Why not use struct percpu_counter and percpu_counter_sum_positive() for this?
> +
> int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
> size_t *lenp, loff_t *ppos)
> {
> dentry_stat.nr_dentry = get_nr_dentry();
> + dentry_stat.nr_unused = get_nr_dentry_unused();
> return proc_dointvec(table, write, buffer, lenp, ppos);
> }
> #endif
> @@ -233,7 +244,7 @@ static void dentry_lru_add(struct dentry *dentry)
> spin_lock(&dcache_lru_lock);
> list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
> dentry->d_sb->s_nr_dentry_unused++;
> - dentry_stat.nr_unused++;
> + this_cpu_inc(nr_dentry_unused);
> spin_unlock(&dcache_lru_lock);
> }
> }
> @@ -242,7 +253,7 @@ static void __dentry_lru_del(struct dentry *dentry)
> {
> list_del_init(&dentry->d_lru);
> dentry->d_sb->s_nr_dentry_unused--;
> - dentry_stat.nr_unused--;
> + this_cpu_dec(nr_dentry_unused);
> }
>
> static void dentry_lru_del(struct dentry *dentry)
> @@ -260,7 +271,7 @@ static void dentry_lru_move_tail(struct dentry *dentry)
> if (list_empty(&dentry->d_lru)) {
> list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
> dentry->d_sb->s_nr_dentry_unused++;
> - dentry_stat.nr_unused++;
> + this_cpu_inc(nr_dentry_unused);
> } else {
> list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
> }
> --
> 1.7.5.4
>
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