Re: still seeing single client NFS4ERR_DELAY / CB_RECALL

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> On Aug 19, 2020, at 5:29 PM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
> 
> On Tue, Aug 18, 2020 at 05:26:26PM -0400, Chuck Lever wrote:
>> 
>>> On Aug 17, 2020, at 6:20 PM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>>> 
>>> On Sun, Aug 16, 2020 at 04:46:00PM -0400, Chuck Lever wrote:
>>> 
>>>> In order of application:
>>>> 
>>>> 5920afa3c85f ("nfsd: hook nfsd_commit up to the nfsd_file cache")
>>>> 961.68user 5252.40system 20:12.30elapsed 512%CPU, 2541 DELAY errors
>>>> These results are similar to v5.3.
>>>> 
>>>> fd4f83fd7dfb ("nfsd: convert nfs4_file->fi_fds array to use nfsd_files")
>>>> Does not build
>>>> 
>>>> eb82dd393744 ("nfsd: convert fi_deleg_file and ls_file fields to nfsd_file")
>>>> 966.92user 5425.47system 33:52.79elapsed 314%CPU, 1330 DELAY errors
>>>> 
>>>> Can you take a look and see if there's anything obvious?
>>> 
>>> Unfortunately nothing about the file cache code is very obvious to me.
>>> I'm looking at it....
>>> 
>>> It adds some new nfserr_jukebox returns in nfsd_file_acquire.  Those
>>> mostly look like kmalloc failures, the one I'm not sure about is the
>>> NFSD_FILE_HASHED check.
>>> 
>>> Or maybe it's the lease break there.
>> 
>> nfsd_file_acquire() always calls fh_verify() before it invokes nfsd_open().
>> Replacing nfs4_get_vfs_file's nfsd_open() call with nfsd_file_acquire() adds
>> almost 10 million fh_verify() calls to my test run.
> 
> Checking out the code as of fd4f83fd7dfb....
> 
> nfsd_file_acquire() calls nfsd_open_verified().
> 
> And nfsd_open() is basically just fh_verify()+nfsd_open_verified().
> 
> So it doesn't look like the replacement of nfsd_open() by
> nfsd_file_acquire() should have changed the number of fh_verify() calls.

I see a lot more vfs_setlease() failures after fd4f83fd7dfb.
check_conflicting_open() fails because "inode is open for write":

1780         if (arg == F_RDLCK)
1781                 return inode_is_open_for_write(inode) ? -EAGAIN : 0;

The behavior on the wire is that the server simply doesn't hand out
many delegations.

NFSv4 OPEN uses nfsd_file_acquire() now, but I don't see CLOSE
releasing the cached file descriptor. Wouldn't that cached
descriptor conflict with subsequent OPENs?


--
Chuck Lever






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