Re: Parallel file locking quite slow with vers=4.0 compared to vers=3

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Jul 21, 2015 at 08:44:44AM +0200, Frank Steiner wrote:
> J. Bruce Fields wrote
> 
> > One way to confirm that might be to run client kernels modified to make
> > the polling behavior (controlled by
> > fs/nfs/nfs4proc.c:nfs4_set_lock_task_retry()) more aggressive, and see
> > if that removes the delays in your case.
> > 
> > If that works, then it might also be worth considering implementing
> > CB_NOTIFY_LOCK:
> > 
> > 	https://tools.ietf.org/html/rfc5661#page-593
> 
> I wouldn't mind to test any kind of patch if someone would find the time
> to provide some. Writing them myself is beyond my skills I'm afraid :-)

Well, I was just thinking of something like this.

(*Not* saying this is what we really want to do, but it might help
confirm where your delay is coming from.)

--b.

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 6f228b5..c119ba7 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5367,7 +5367,7 @@ int nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, const nfs4
 	return err;
 }
 
-#define NFS4_LOCK_MINTIMEOUT (1 * HZ)
+#define NFS4_LOCK_MINTIMEOUT (1 * HZ / 10)
 #define NFS4_LOCK_MAXTIMEOUT (30 * HZ)
 
 /*