Re: [External] Re: [PATCH] files: Use rcu lock to get the file structures for better performance

On Thu, May 21, 2020 at 11:21 PM Matthew Wilcox [off-list ref] wrote:

On Thu, May 21, 2020 at 08:38:35PM +0800, Muchun Song wrote:

quoted

There is another safe way to get the file structure without
holding the files->file_lock. That is rcu lock, and this way
has better performance. So use the rcu lock instead of the
files->file_lock.

What makes you think this is safe?  Are you actually seeing contention
on this spinlock?

I have read the doc which is in the Documentation/filesystems/files.txt.
If my understanding is correct, I think it is safe to use rcu lock.

Thanks.

-- 
Yours,
Muchun