From: Jason Baron <jbaron@akamai.com>
To: Vincent Whitchurch <vincent.whitchurch@axis.com>,
Jim Cromie <jim.cromie@gmail.com>
Cc: gregkh@linuxfoundation.org, robdclark@gmail.com, sean@poorly.run,
daniel.vetter@ffwll.ch, seanpaul@chromium.org, lyude@redhat.com,
linux-kernel@vger.kernel.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, dri-devel@lists.freedesktop.org,
amd-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org, quic_saipraka@quicinc.com,
will@kernel.org, catalin.marinas@arm.com,
quic_psodagud@quicinc.com, maz@kernel.org, arnd@arndb.de,
linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, mingo@redhat.com
Subject: Re: [PATCH v10 08/10] dyndbg: add print-to-tracefs, selftest with it - RFC
Date: Fri, 12 Nov 2021 10:08:41 -0500 [thread overview]
Message-ID: <f3914fa9-8b22-d54e-3f77-d998e74094b9@akamai.com> (raw)
In-Reply-To: <20211112114953.GA1381@axis.com>
On 11/12/21 6:49 AM, Vincent Whitchurch wrote:
> On Thu, Nov 11, 2021 at 03:02:04PM -0700, Jim Cromie wrote:
>> Sean Paul proposed, in:
>> https://urldefense.com/v3/__https://patchwork.freedesktop.org/series/78133/__;!!GjvTz_vk!HcKnMRByYkIdyF1apqQjlN5aBIomzJR1an3YWXM6KXs0EftVMQdrewRA8Dki4A$
>> drm/trace: Mirror DRM debug logs to tracefs
>>
>> His patchset's objective is to be able to independently steer some of
>> the drm.debug stream to an alternate tracing destination, by splitting
>> drm_debug_enabled() into syslog & trace flavors, and enabling them
>> separately. 2 advantages were identified:
>>
>> 1- syslog is heavyweight, tracefs is much lighter
>> 2- separate selection of enabled categories means less traffic
>>
>> Dynamic-Debug can do 2nd exceedingly well:
>>
>> A- all work is behind jump-label's NOOP, zero off cost.
>> B- exact site selectivity, precisely the useful traffic.
>> can tailor enabled set interactively, at shell.
>>
>> Since the tracefs interface is effective for drm (the threads suggest
>> so), adding that interface to dynamic-debug has real potential for
>> everyone including drm.
>>
>> if CONFIG_TRACING:
>>
>> Grab Sean's trace_init/cleanup code, use it to provide tracefs
>> available by default to all pr_debugs. This will likely need some
>> further per-module treatment; perhaps something reflecting hierarchy
>> of module,file,function,line, maybe with a tuned flattening.
>>
>> endif CONFIG_TRACING
>>
>> Add a new +T flag to enable tracing, independent of +p, and add and
>> use 3 macros: dyndbg_site_is_enabled/logging/tracing(), to encapsulate
>> the flag checks. Existing code treats T like other flags.
>
> I posted a patchset a while ago to do something very similar, but that
> got stalled for some reason and I unfortunately didn't follow it up:
>
> https://urldefense.com/v3/__https://lore.kernel.org/lkml/20200825153338.17061-1-vincent.whitchurch@axis.com/__;!!GjvTz_vk!HcKnMRByYkIdyF1apqQjlN5aBIomzJR1an3YWXM6KXs0EftVMQdrewRGytKHPg$
>
> A key difference between that patchset and this patch (besides that
> small fact that I used +x instead of +T) was that my patchset allowed
> the dyndbg trace to be emitted to the main buffer and did not force them
> to be in an instance-specific buffer.
Yes, I agree I'd prefer that we print here to the 'main' buffer - it seems to keep things simpler and easier to combine the output from different
sources as you mentioned.
Thanks,
-Jason
>
> That feature is quite important at least for my use case since I often
> use dyndbg combined with function tracing, and the latter doesn't work
> on non-main instances according to Documentation/trace/ftrace.rst.
>
> For example, here's a random example of a bootargs from one of my recent
> debugging sessions:
>
> trace_event=printk:* ftrace_filter=_mmc*,mmc*,sd*,dw_mci*,mci*
> ftrace=function trace_buf_size=20M dyndbg="file drivers/mmc/* +x"
>
next prev parent reply other threads:[~2021-11-12 15:09 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-11 22:01 [PATCH v10 00/10 RESEND] use DYNAMIC_DEBUG to implement DRM.debug & DRM.trace Jim Cromie
2021-11-11 22:01 ` [PATCH v10 01/10] dyndbg: add DEFINE_DYNAMIC_DEBUG_BITGRPS macro and callbacks Jim Cromie
2021-11-11 22:01 ` [PATCH v10 02/10] drm: fix doc grammar Jim Cromie
2021-11-11 22:01 ` [PATCH v10 03/10] amdgpu: use dyndbg.BITGRPS to control existing pr_debugs Jim Cromie
2021-11-11 22:02 ` [PATCH v10 04/10] i915/gvt: trim spaces from pr_debug "gvt: core:" prefixes Jim Cromie
2021-11-11 22:02 ` [PATCH v10 05/10] i915/gvt: use dyndbg.BITGRPS for existing pr_debugs Jim Cromie
2021-11-11 22:02 ` [PATCH v10 06/10] drm_print: add choice to use dynamic debug in drm-debug Jim Cromie
2021-11-11 22:02 ` [PATCH v10 07/10] drm_print: instrument drm_debug_enabled Jim Cromie
2021-11-11 22:02 ` [PATCH v10 08/10] dyndbg: add print-to-tracefs, selftest with it - RFC Jim Cromie
2021-11-12 11:49 ` Vincent Whitchurch
2021-11-12 15:08 ` Jason Baron [this message]
2021-11-12 17:07 ` Steven Rostedt
2021-11-12 17:32 ` Jason Baron
2021-11-12 17:54 ` Steven Rostedt
2021-11-16 8:46 ` Pekka Paalanen
2021-11-18 14:29 ` Jason Baron
2021-11-18 15:24 ` Pekka Paalanen
2021-11-19 16:21 ` Jason Baron
2021-11-19 22:46 ` jim.cromie
2021-11-19 22:54 ` Steven Rostedt
2021-11-25 13:51 ` Vincent Whitchurch
2021-11-22 9:02 ` Pekka Paalanen
2021-11-22 22:42 ` jim.cromie
2021-11-23 8:45 ` Pekka Paalanen
2021-11-23 9:32 ` Simon Ser
2021-12-08 5:16 ` jim.cromie
2021-12-09 15:09 ` Vincent Whitchurch
2021-11-11 22:02 ` [PATCH v10 09/10] dyndbg: create DEFINE_DYNAMIC_DEBUG_LOG|TRACE_GROUPS Jim Cromie
2021-11-11 22:02 ` [PATCH v10 10/10] drm: use DEFINE_DYNAMIC_DEBUG_TRACE_GROUPS in 3 places Jim Cromie
-- strict thread matches above, loose matches on Subject: below --
2021-11-05 19:26 [PATCH v10 00/10] use DYNAMIC_DEBUG to implement DRM.debug & DRM.trace Jim Cromie
2021-11-05 19:26 ` [PATCH v10 08/10] dyndbg: add print-to-tracefs, selftest with it - RFC Jim Cromie
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f3914fa9-8b22-d54e-3f77-d998e74094b9@akamai.com \
--to=jbaron@akamai.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=arnd@arndb.de \
--cc=catalin.marinas@arm.com \
--cc=daniel.vetter@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=gregkh@linuxfoundation.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=intel-gvt-dev@lists.freedesktop.org \
--cc=jim.cromie@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lyude@redhat.com \
--cc=mathieu.desnoyers@efficios.com \
--cc=maz@kernel.org \
--cc=mingo@redhat.com \
--cc=quic_psodagud@quicinc.com \
--cc=quic_saipraka@quicinc.com \
--cc=robdclark@gmail.com \
--cc=rostedt@goodmis.org \
--cc=sean@poorly.run \
--cc=seanpaul@chromium.org \
--cc=vincent.whitchurch@axis.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).