On Wed, Feb 14, 2018 at 02:52:00PM +0100, Carlos Maiolino wrote:

On Wed, Feb 14, 2018 at 10:58:14AM +1100, Dave Chinner wrote:

quoted

On Tue, Feb 13, 2018 at 03:17:31PM -0800, Darrick J. Wong wrote:

quoted

On Tue, Feb 13, 2018 at 08:21:06AM +1100, Dave Chinner wrote:

quoted

On Mon, Feb 12, 2018 at 10:29:48AM -0800, Darrick J. Wong wrote:

quoted

On Mon, Feb 12, 2018 at 02:00:05PM +0100, Carlos Maiolino wrote:

quoted

Remove unused legacy btree traces from IRIX era.

Signed-off-by: Carlos Maiolino <redacted>
---

Talking to Dave about it, he mentioned XFS_BTREE_TRACE_CURSOR might be worth to
turn into a proper ftrace trace point, so I didn't touch _CURSOR traces in this
patchset, and a proper conversion will be sent later, unless it's not worth at
all, and I should send a V2 also removing TRACE_CURSOR.

TBH I wonder the opposite -- why not turn all of these into tracepoints?

TBH, we haven't used them in at least 15 years. What value do they
provide apart from making the traces even noisier (and potentially
more lossy) than they already are?

FWIW adding trace_printks to some of those functions was rather useful
for checking that the unusual refcount and rmap btree semantics actually
resulted in calls to the desired btree functions.  I wish I'd cleaned up
that debugging patch and sent it, but it's lost now.

I see your point, although, for me, it sounds like a very specific debug case,
and not something which would add enough benefit to have these extra debug
traces lying around.

I mean, if we keep adding trace points for many single debug use-cases, we would
end up with tons of trace points in xfs, which are not used in 99% of the debugging
processes.

But well, I don't have a decent knowledge in the Btrees infra-structure yet to
give a more detailed reason if such extra trace points would be useful or not in
several situations. So, this is just my $0.02, based on the amount of trace
points we already have, where, most of time I use one or another, and yet, I
need to add my own trace_printks, so, particularly, I don't think adding such
extra traces in Btree code would be that useful in a long-term period, but well,
as I said, just my $0.02.

We already have 531 tracepoints, a few more probably isn't going to
hurt.  That said, if you want to send a patch cleaning out both of the
old trace macros I'd take it.  At worst, if I or anyone else ever come
across a need to add tracepoints to the core btree code they're not hard
to add.

--D

quoted

Ok, so the non-cursor traces would have been useful to you.
That's fine - I just don't want to add stuff that doesn't have any
specific use because it's already hard enough to filter traces down
to just the things we need to see....

quoted

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

-- 
Carlos
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