From: Trond Myklebust <trondmy@hammerspace.com>
To: "bfields@fieldses.org" <bfields@fieldses.org>,
"daire@dneg.com" <daire@dneg.com>
Cc: "linux-cachefs@redhat.com" <linux-cachefs@redhat.com>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: Adventures in NFS re-exporting
Date: Tue, 15 Sep 2020 19:59:27 +0000 [thread overview]
Message-ID: <4d1d7cd0076d98973a56e89c92e4ff0474aa0e14.camel@hammerspace.com> (raw)
In-Reply-To: <20200915172140.GA32632@fieldses.org>
On Tue, 2020-09-15 at 13:21 -0400, J. Bruce Fields wrote:
> On Mon, Sep 07, 2020 at 06:31:00PM +0100, Daire Byrne wrote:
> > 1) The kernel can drop entries out of the NFS client inode cache
> > (under memory cache churn) when those filehandles are still being
> > used by the knfsd's remote clients resulting in sporadic and random
> > stale filehandles. This seems to be mostly for directories from
> > what I've seen. Does the NFS client not know that knfsd is still
> > using those files/dirs? The workaround is to never drop inode &
> > dentry caches on the re-export servers (vfs_cache_pressure=1). This
> > also helps to ensure that we actually make the most of our
> > actimeo=3600,nocto mount options for the full specified time.
>
> I thought reexport worked by embedding the original server's
> filehandles
> in the filehandles given out by the reexporting server.
>
> So, even if nothing's cached, when the reexporting server gets a
> filehandle, it should be able to extract the original filehandle from
> it
> and use that.
>
> I wonder why that's not working?
NFSv3? If so, I suspect it is because we never wrote a lookupp()
callback for it.
>
> > 4) With an NFSv4 re-export, lots of open/close requests (hundreds
> > per
> > second) quickly eat up the CPU on the re-export server and perf top
> > shows we are mostly in native_queued_spin_lock_slowpath.
>
> Any statistics on who's calling that function?
>
> > Does NFSv4
> > also need an open file cache like that added to NFSv3? Our
> > workaround
> > is to either fix the thing doing lots of repeated open/closes or
> > use
> > NFSv3 instead.
>
> NFSv4 uses the same file cache. It might be the file cache that's at
> fault, in fact....
>
> --b.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com
next prev parent reply other threads:[~2020-09-15 20:02 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 17:31 Adventures in NFS re-exporting Daire Byrne
2020-09-08 9:40 ` Mkrtchyan, Tigran
2020-09-08 11:06 ` Daire Byrne
2020-09-15 17:21 ` J. Bruce Fields
2020-09-15 19:59 ` Trond Myklebust [this message]
2020-09-16 16:01 ` Daire Byrne
2020-10-19 16:19 ` Daire Byrne
2020-10-19 17:53 ` [PATCH 0/2] Add NFSv3 emulation of the lookupp operation trondmy
2020-10-19 17:53 ` [PATCH 1/2] NFSv3: Refactor nfs3_proc_lookup() to split out the dentry trondmy
2020-10-19 17:53 ` [PATCH 2/2] NFSv3: Add emulation of the lookupp() operation trondmy
2020-10-19 20:05 ` [PATCH v2 0/2] Add NFSv3 emulation of the lookupp operation trondmy
2020-10-19 20:05 ` [PATCH v2 1/2] NFSv3: Refactor nfs3_proc_lookup() to split out the dentry trondmy
2020-10-19 20:05 ` [PATCH v2 2/2] NFSv3: Add emulation of the lookupp() operation trondmy
2020-10-20 18:37 ` [PATCH v3 0/3] Add NFSv3 emulation of the lookupp operation trondmy
2020-10-20 18:37 ` [PATCH v3 1/3] NFSv3: Refactor nfs3_proc_lookup() to split out the dentry trondmy
2020-10-20 18:37 ` [PATCH v3 2/3] NFSv3: Add emulation of the lookupp() operation trondmy
2020-10-20 18:37 ` [PATCH v3 3/3] NFSv4: Observe the NFS_MOUNT_SOFTREVAL flag in _nfs4_proc_lookupp trondmy
2020-10-21 9:33 ` Adventures in NFS re-exporting Daire Byrne
2020-11-09 16:02 ` bfields
2020-11-12 13:01 ` Daire Byrne
2020-11-12 13:57 ` bfields
2020-11-12 18:33 ` Daire Byrne
2020-11-12 20:55 ` bfields
2020-11-12 23:05 ` Daire Byrne
2020-11-13 14:50 ` bfields
2020-11-13 22:26 ` bfields
2020-11-14 12:57 ` Daire Byrne
2020-11-16 15:18 ` bfields
2020-11-16 15:53 ` bfields
2020-11-16 19:21 ` Daire Byrne
2020-11-16 15:29 ` Jeff Layton
2020-11-16 15:56 ` bfields
2020-11-16 16:03 ` Jeff Layton
2020-11-16 16:14 ` bfields
2020-11-16 16:38 ` Jeff Layton
2020-11-16 19:03 ` bfields
2020-11-16 20:03 ` Jeff Layton
2020-11-17 3:16 ` bfields
2020-11-17 3:18 ` [PATCH 1/4] nfsd: move fill_{pre,post}_wcc to nfsfh.c J. Bruce Fields
2020-11-17 3:18 ` [PATCH 2/4] nfsd: pre/post attr is using wrong change attribute J. Bruce Fields
2020-11-17 12:34 ` Jeff Layton
2020-11-17 15:26 ` J. Bruce Fields
2020-11-17 15:34 ` Jeff Layton
2020-11-20 22:38 ` J. Bruce Fields
2020-11-20 22:39 ` [PATCH 1/8] nfsd: only call inode_query_iversion in the I_VERSION case J. Bruce Fields
2020-11-20 22:39 ` [PATCH 2/8] nfsd: simplify nfsd4_change_info J. Bruce Fields
2020-11-20 22:39 ` [PATCH 3/8] nfsd: minor nfsd4_change_attribute cleanup J. Bruce Fields
2020-11-21 0:34 ` Jeff Layton
2020-11-20 22:39 ` [PATCH 4/8] nfsd4: don't query change attribute in v2/v3 case J. Bruce Fields
2020-11-20 22:39 ` [PATCH 5/8] nfs: use change attribute for NFS re-exports J. Bruce Fields
2020-11-20 22:39 ` [PATCH 6/8] nfsd: move change attribute generation to filesystem J. Bruce Fields
2020-11-21 0:58 ` Jeff Layton
2020-11-21 1:01 ` J. Bruce Fields
2020-11-21 13:00 ` Jeff Layton
2020-11-20 22:39 ` [PATCH 7/8] nfsd: skip some unnecessary stats in the v4 case J. Bruce Fields
2020-11-20 22:39 ` [PATCH 8/8] Revert "nfsd4: support change_attr_type attribute" J. Bruce Fields
2020-11-20 22:44 ` [PATCH 2/4] nfsd: pre/post attr is using wrong change attribute J. Bruce Fields
2020-11-21 1:03 ` Jeff Layton
2020-11-21 21:44 ` Daire Byrne
2020-11-22 0:02 ` bfields
2020-11-22 1:55 ` Daire Byrne
2020-11-22 3:03 ` bfields
2020-11-23 20:07 ` Daire Byrne
2020-11-17 15:25 ` J. Bruce Fields
2020-11-17 3:18 ` [PATCH 3/4] nfs: don't mangle i_version on NFS J. Bruce Fields
2020-11-17 12:27 ` Jeff Layton
2020-11-17 14:14 ` J. Bruce Fields
2020-11-17 3:18 ` [PATCH 4/4] nfs: support i_version in the NFSv4 case J. Bruce Fields
2020-11-17 12:34 ` Jeff Layton
2020-11-24 20:35 ` Adventures in NFS re-exporting Daire Byrne
2020-11-24 21:15 ` bfields
2020-11-24 22:15 ` Frank Filz
2020-11-25 14:47 ` 'bfields'
2020-11-25 16:25 ` Frank Filz
2020-11-25 19:03 ` 'bfields'
2020-11-26 0:04 ` Frank Filz
2020-11-25 17:14 ` Daire Byrne
2020-11-25 19:31 ` bfields
2020-12-03 12:20 ` Daire Byrne
2020-12-03 18:51 ` bfields
2020-12-03 20:27 ` Trond Myklebust
2020-12-03 21:13 ` bfields
2020-12-03 21:32 ` Frank Filz
2020-12-03 21:34 ` Trond Myklebust
2020-12-03 21:45 ` Frank Filz
2020-12-03 21:57 ` Trond Myklebust
2020-12-03 22:04 ` bfields
2020-12-03 22:14 ` Trond Myklebust
2020-12-03 22:39 ` Frank Filz
2020-12-03 22:50 ` Trond Myklebust
2020-12-03 23:34 ` Frank Filz
2020-12-03 22:44 ` bfields
2020-12-03 21:54 ` bfields
2020-12-03 22:45 ` bfields
2020-12-03 22:53 ` Trond Myklebust
2020-12-03 23:16 ` bfields
2020-12-03 23:28 ` Frank Filz
2020-12-04 1:02 ` Trond Myklebust
2020-12-04 1:41 ` bfields
2020-12-04 2:27 ` Trond Myklebust
2020-09-17 16:01 ` Daire Byrne
2020-09-17 19:09 ` bfields
2020-09-17 20:23 ` Frank van der Linden
2020-09-17 21:57 ` bfields
2020-09-19 11:08 ` Daire Byrne
2020-09-22 16:43 ` Chuck Lever
2020-09-23 20:25 ` Daire Byrne
2020-09-23 21:01 ` Frank van der Linden
2020-09-26 9:00 ` Daire Byrne
2020-09-28 15:49 ` Frank van der Linden
2020-09-28 16:08 ` Chuck Lever
2020-09-28 17:42 ` Frank van der Linden
2020-09-22 12:31 ` Daire Byrne
2020-09-22 13:52 ` Trond Myklebust
2020-09-23 12:40 ` J. Bruce Fields
2020-09-23 13:09 ` Trond Myklebust
2020-09-23 17:07 ` bfields
2020-09-30 19:30 ` [Linux-cachefs] " Jeff Layton
2020-10-01 0:09 ` Daire Byrne
2020-10-01 10:36 ` Jeff Layton
2020-10-01 12:38 ` Trond Myklebust
2020-10-01 16:39 ` Jeff Layton
2020-10-05 12:54 ` Daire Byrne
2020-10-13 9:59 ` Daire Byrne
2020-10-01 18:41 ` J. Bruce Fields
2020-10-01 19:24 ` Trond Myklebust
2020-10-01 19:26 ` bfields
2020-10-01 19:29 ` Trond Myklebust
2020-10-01 19:51 ` bfields
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