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From: jim.cromie@gmail.com
To: Jason Baron <jbaron@akamai.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	amd-gfx mailing list <amd-gfx@lists.freedesktop.org>,
	intel-gvt-dev@lists.freedesktop.org,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH v7 6/8] drm_print: instrument drm_debug_enabled
Date: Sun, 5 Sep 2021 12:50:48 -0600	[thread overview]
Message-ID: <CAJfuBxwqdy888_v7a6U5BYPZxDkQAB4SLPdFyEv+MW98ByNuQg@mail.gmail.com> (raw)
In-Reply-To: <20210831202133.2165222-7-jim.cromie@gmail.com>

On Tue, Aug 31, 2021 at 2:21 PM Jim Cromie <jim.cromie@gmail.com> wrote:
>
> Duplicate drm_debug_enabled() code into both "basic" and "dyndbg"
> ifdef branches.  Then add a pr_debug("todo: ...") into the "dyndbg"
> branch.
>
> Then convert the "dyndbg" branch's code to a macro, so that its
> pr_debug() get its callsite info from the invoking function, instead
> of from drm_debug_enabled() itself.
>
> This gives us unique callsite info for the 8 remaining users of
> drm_debug_enabled(), and lets us enable them individually to see how
> much logging traffic they generate.  The oft-visited callsites can
> then be reviewed for runtime cost and possible optimizations.
>
> Heres what we get:
>
> bash-5.1# modprobe drm
> dyndbg: 384 debug prints in module drm
> bash-5.1# grep todo: /proc/dynamic_debug/control
> drivers/gpu/drm/drm_edid.c:1843 [drm]connector_bad_edid =_ "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_print.c:309 [drm]___drm_dbg =p "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_print.c:286 [drm]__drm_dev_dbg =p "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_vblank.c:1491 [drm]drm_vblank_restore =_ "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_vblank.c:787 [drm]drm_crtc_vblank_helper_get_vblank_timestamp_internal =_ "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_vblank.c:410 [drm]drm_crtc_accurate_vblank_count =_ "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_atomic_uapi.c:1457 [drm]drm_mode_atomic_ioctl =_ "todo: maybe avoid via dyndbg\012"
> drivers/gpu/drm/drm_edid_load.c:178 [drm]edid_load =_ "todo: maybe avoid via dyndbg\012"
>
> At quick glance, edid won't qualify, drm_print might, drm_vblank is
> strongest chance, maybe atomic-ioctl too.
>
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---

heres 120 seconds of enabled todos, from this patch

[jimc@frodo wk-next]$ journalctl -b0 | grep todo | grep 'frodo kernel'
[jimc@frodo wk-next]$ sudo su -c 'echo format ^todo: +pfml >
/proc/dynamic_debug/control;  sleep 120; echo format ^todo: -p >
/proc/dynamic_debug/control'
[sudo] password for jimc:
[jimc@frodo wk-next]$ journalctl -b0 | grep todo | grep 'frodo kernel'
 > todo-120-log
[jimc@frodo wk-next]$ wc todo-120-log
  228  2516 24066 todo-120-log

so overall thats not too much work, not so many bitchecks as to be
worth avoiding.

I think I'll try hitting it with my new igt-tools hammer, see what breaks :-)


[jimc@frodo wk-next]$ hsto todo-120-log
120 :  drm:drm_crtc_vblank_helper_get_vblank_timestamp_internal:787:
todo: maybe avoid via dyndbg
40 :  i915:process_csb:1904: todo: maybe avoid via dyndbg
20 :  drm:drm_vblank_restore:1491: todo: maybe avoid via dyndbg
20 :  drm:drm_crtc_accurate_vblank_count:410: todo: maybe avoid via dyndbg
20 :  i915:skl_print_wm_changes:6068: todo: maybe avoid via dyndbg
2 :  dyndbg: applied: func="" file="" module="" format="^todo:" lineno=0-0
2 :  dyndbg: parsed: func="" file="" module="" format="^todo:" lineno=0-0
1 :  dyndbg: split into words: "format" "^todo:" "-p"
1 :  dyndbg: split into words: "format" "^todo:" "+pfml"
1 :  dyndbg: query 0: "format ^todo: -p" mod:*
1 :  dyndbg: query 0: "format ^todo: +pfml" mod:*

  reply	other threads:[~2021-09-05 18:51 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31 20:21 [PATCH v7 0/8] use DYNAMIC_DEBUG to implement DRM.debug Jim Cromie
2021-08-31 20:21 ` [PATCH v7 1/8] dyndbg: add DEFINE_DYNAMIC_DEBUG_CATEGORIES and callbacks Jim Cromie
2021-08-31 20:21 ` [PATCH v7 2/8] dyndbg: remove spaces in pr_debug "gvt: core:" etc prefixes Jim Cromie
2021-08-31 20:21 ` [PATCH v7 3/8] i915/gvt: use DEFINE_DYNAMIC_DEBUG_CATEGORIES to create "gvt:core:" etc categories Jim Cromie
2021-09-03 11:07   ` [Intel-gfx] " Tvrtko Ursulin
2021-09-03 19:22     ` jim.cromie
2021-09-06 12:26       ` Tvrtko Ursulin
     [not found]         ` <CAJfuBxymoFx79kQzGw_Gxv1vk7kVaTN-V0Hn694C6kT=kP7u2A@mail.gmail.com>
2021-09-07 15:14           ` Tvrtko Ursulin
2021-09-07 17:26             ` jim.cromie
2021-08-31 20:21 ` [PATCH v7 4/8] amdgpu: use DEFINE_DYNAMIC_DEBUG_CATEGORIES Jim Cromie
2021-08-31 20:21 ` [PATCH v7 5/8] drm_print: add choice to use dynamic debug in drm-debug Jim Cromie
2021-09-03 11:15   ` [Intel-gfx] " Tvrtko Ursulin
2021-09-03 21:57     ` jim.cromie
2021-09-06 10:20       ` Tvrtko Ursulin
2021-09-06 18:24         ` jim.cromie
2021-08-31 20:21 ` [PATCH v7 6/8] drm_print: instrument drm_debug_enabled Jim Cromie
2021-09-05 18:50   ` jim.cromie [this message]
2021-08-31 20:21 ` [PATCH v7 7/8] amdgpu_ucode: reduce number of pr_debug calls Jim Cromie
2021-08-31 20:21 ` [PATCH v7 8/8] nouveau: fold multiple DRM_DEBUG_DRIVERs together Jim Cromie

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