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From: "Benjamin Coddington" <bcodding@redhat.com>
To: "Chuck Lever III" <chuck.lever@oracle.com>
Cc: trondmy@kernel.org, "Linux NFS Mailing List" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v9 03/27] NFS: Trace lookup revalidation failure
Date: Wed, 09 Mar 2022 16:35:53 -0500	[thread overview]
Message-ID: <FBED54D6-7C0F-4AE1-961E-78D3DDE00F6F@redhat.com> (raw)
In-Reply-To: <52214581-7C9A-425A-9B8E-082B7ACE23C1@oracle.com>

On 9 Mar 2022, at 10:28, Chuck Lever III wrote:

>> On Mar 9, 2022, at 8:42 AM, Benjamin Coddington <bcodding@redhat.com> 
>> wrote:
>>
>> On 24 Feb 2022, at 21:09, Trond Myklebust wrote:
>>> On Thu, 2022-02-24 at 09:14 -0500, Benjamin Coddington wrote:
>>>> There's a path through nfs4_lookup_revalidate that will now only 
>>>> produce
>>>> this exit tracepoint.  Does it need the _enter tracepoint added?
>>>
>>> You're thinking about the nfs_lookup_revalidate_delegated() path? 
>>> The
>>> _enter() tracepoint doesn't provide any useful information that 
>>> isn't
>>> already provided by the _exit(), AFAICS.
>>
>> No, the path through nfs4_do_lookup_revalidate(), reval_dentry: jump. 
>>  But I
>> agree there's not much value in the _enter() tracepoint.  Maybe we 
>> can
>> remove it, and _exit more like _done.
>>
>> I am thinking about hearing back from folks about mis-matched 
>> _enter() and
>> _exit() results, but also realize this is nit-picking.
>
> I think the _enter / _exit trace points simply replaced
> dprintk call sites which did much the same reporting.
> Maybe we should consider replacing some of these because
> we can rely on function call tracing instead.
>
> But generally we like to see trace points that report
> exceptional events rather than "I made it to this point".
> The latter category of trace points are interesting
> while code is under development but often loses its
> value once the code is in the field.

Instead of "hearing back from folks" I should have said "I worry our QE 
team
is going to discover and possibly report as a bug". :P  Thanks for 
filling
in Chuck!

Ben


  reply	other threads:[~2022-03-09 21:36 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-27 23:12 [PATCH v9 00/27] Readdir improvements trondmy
2022-02-27 23:12 ` [PATCH v9 01/27] NFS: Return valid errors from nfs2/3_decode_dirent() trondmy
2022-02-27 23:12   ` [PATCH v9 02/27] NFS: constify nfs_server_capable() and nfs_have_writebacks() trondmy
2022-02-27 23:12     ` [PATCH v9 03/27] NFS: Trace lookup revalidation failure trondmy
2022-02-27 23:12       ` [PATCH v9 04/27] NFS: Initialise the readdir verifier as best we can in nfs_opendir() trondmy
2022-02-27 23:12         ` [PATCH v9 05/27] NFS: Use kzalloc() to avoid initialising the nfs_open_dir_context trondmy
2022-02-27 23:12           ` [PATCH v9 06/27] NFS: Calculate page offsets algorithmically trondmy
2022-02-27 23:12             ` [PATCH v9 07/27] NFS: Store the change attribute in the directory page cache trondmy
2022-02-27 23:12               ` [PATCH v9 08/27] NFS: Don't re-read the entire page cache to find the next cookie trondmy
2022-02-27 23:12                 ` [PATCH v9 09/27] NFS: Don't advance the page pointer unless the page is full trondmy
2022-02-27 23:12                   ` [PATCH v9 10/27] NFS: Adjust the amount of readahead performed by NFS readdir trondmy
2022-02-27 23:12                     ` [PATCH v9 11/27] NFS: If the cookie verifier changes, we must invalidate the page cache trondmy
2022-02-27 23:12                       ` [PATCH v9 12/27] NFS: Simplify nfs_readdir_xdr_to_array() trondmy
2022-02-27 23:12                         ` [PATCH v9 13/27] NFS: Reduce use of uncached readdir trondmy
2022-02-27 23:12                           ` [PATCH v9 14/27] NFS: Improve heuristic for readdirplus trondmy
2022-02-27 23:12                             ` [PATCH v9 15/27] NFS: Don't ask for readdirplus unless it can help nfs_getattr() trondmy
2022-02-27 23:12                               ` [PATCH v9 16/27] NFSv4: Ask for a full XDR buffer of readdir goodness trondmy
2022-02-27 23:12                                 ` [PATCH v9 17/27] NFS: Readdirplus can't help lookup for case insensitive filesystems trondmy
2022-02-27 23:12                                   ` [PATCH v9 18/27] NFS: Don't request readdirplus when revalidation was forced trondmy
2022-02-27 23:12                                     ` [PATCH v9 19/27] NFS: Add basic readdir tracing trondmy
2022-02-27 23:12                                       ` [PATCH v9 20/27] NFS: Trace effects of readdirplus on the dcache trondmy
2022-02-27 23:12                                         ` [PATCH v9 21/27] NFS: Trace effects of the readdirplus heuristic trondmy
2022-02-27 23:12                                           ` [PATCH v9 22/27] NFS: Clean up page array initialisation/free trondmy
2022-02-27 23:12                                             ` [PATCH v9 23/27] NFS: Convert readdir page cache to use a cookie based index trondmy
2022-02-27 23:12                                               ` [PATCH v9 24/27] NFS: Fix up forced readdirplus trondmy
2022-02-27 23:12                                                 ` [PATCH v9 25/27] NFS: Remove unnecessary cache invalidations for directories trondmy
2022-02-27 23:12                                                   ` [PATCH v9 26/27] NFS: Optimise away the previous cookie field trondmy
2022-02-27 23:12                                                     ` [PATCH v9 27/27] NFS: Cache all entries in the readdirplus reply trondmy
2022-03-09 20:01                                               ` [PATCH v9 23/27] NFS: Convert readdir page cache to use a cookie based index Benjamin Coddington
2022-03-09 21:03                                                 ` Benjamin Coddington
2022-03-10 21:07                                                 ` Trond Myklebust
2022-03-11 11:58                                                   ` Benjamin Coddington
2022-03-11 14:02                                                     ` Trond Myklebust
2022-03-11 16:14                                                       ` Benjamin Coddington
2022-03-11 16:51                                                         ` Trond Myklebust
2022-03-09 17:39                             ` [PATCH v9 14/27] NFS: Improve heuristic for readdirplus Benjamin Coddington
2022-03-10 14:31                               ` [PATCH] NFS: Trigger "ls -l" readdir heuristic sooner Benjamin Coddington
2022-03-16 22:25                                 ` Olga Kornievskaia
2022-03-10 20:15                               ` [PATCH v9 14/27] NFS: Improve heuristic for readdirplus Trond Myklebust
2022-03-11 11:28                                 ` Benjamin Coddington
2022-03-01 19:09               ` [PATCH v9 07/27] NFS: Store the change attribute in the directory page cache Anna Schumaker
2022-03-01 23:11                 ` Trond Myklebust
2022-03-09 13:42       ` [PATCH v9 03/27] NFS: Trace lookup revalidation failure Benjamin Coddington
2022-03-09 15:28         ` Chuck Lever III
2022-03-09 21:35           ` Benjamin Coddington [this message]
2022-03-09 21:32 ` [PATCH v9 00/27] Readdir improvements Benjamin Coddington

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