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Re: [patch 0/5] activate & deactivate dprintks individually and severally
- From: Jason Baron <jbaron at redhat dot com>
- To: linux-kernel at vger dot kernel dot org
- Cc: Linux NFS ML <linux-nfs at vger dot kernel dot org>, Linux NFSv4 ML <nfsv4 at linux-nfs dot org>, SystemTAP ML <systemtap at sources dot redhat dot com>, gnb at sgi dot com
- Date: Wed, 21 Jan 2009 10:28:58 -0500
- Subject: Re: [patch 0/5] activate & deactivate dprintks individually and severally
- References: <20090120012930.020621000@sgi.com>
On Tue, Jan 20, 2009 at 12:29:30PM +1100, Greg Banks wrote:
>
> As mentioned in the recent discussion on NFS trace points on the NFS &
> SystemTap mailing lists. This patch allows field support staff and
> kernel developers debug kernel problems, by enabling them to treat
> dprintks as precise trace points rather than syslog spamming tools.
>
> This is a forward ported (from 2.6.16), updated, and split version
> of a patch that has been used in SGI's internal development tree for
> the last few months. The very first version of this was used about
> eighteen months ago when debugging NFS/RDMA, which has an enormous
> number of dprintks and no other way to debug it.
>
> Jason Baron suggested I post it here for review and contrast with
> his dynamic dprintk feature.
>
yes, these two patch sets are very similar in the problem that they are
addressing. For me, one of the core differences, is that 'dprintk' has
per-debug statement control, while my solution, 'dynamic debug' has a
more per-module focused control. 'dprintk' thus checks a different
variable per-debug line to see if its enabled. On the other hand
'dynamic debug' can check 1 global variable (in the most common cases),
to see if its enabled or not. I think we can layer per-line check on top
of the 1 global variable check and have a more efficient solution that
still allows for fine-grained debugging.
'dprintk' also has a richer user interface, which allows for file, line,
module, and statement control.
Thus, I think Greg and I can work together and combine the best features
of both patches. We will re-post a combined solution.
thanks,
-Jason