Re: ext4 extent status tree LRU locking

From: Dave Hansen
Date: Fri Jun 14 2013 - 11:57:52 EST

On 06/14/2013 07:09 AM, Zheng Liu wrote:
> - INIT_LIST_HEAD(&scanned);
> -
> spin_lock(&sbi->s_es_lru_lock);
> + list_sort(NULL, &sbi->s_es_lru, ext4_inode_touch_time_cmp);
> list_for_each_safe(cur, tmp, &sbi->s_es_lru) {

How long can this list get? I have the feeling this might get a bit
painful, especially on a NUMA machine.

But, it definitely eliminates the spinlock contention that I was seeing.
The top ext4 function in my profiles is way down under 1% of CPU time
now. Thanks for the quick response, and please let me know if you need
any further testing.
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