| Message ID | 20220516225640.3102269-1-jim.cromie@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | DRM.debug on DYNAMIC_DEBUG, add trace events | expand |
On Mon, May 16, 2022 at 04:56:13PM -0600, Jim Cromie wrote: > DRM.debug API is 23 macros, issuing 10 exclusive categories of debug > messages. By rough count, they are used 5140 times in the kernel. > These all call drm_dbg or drm_devdbg, which call drm_debug_enabled(), > which checks bits in global __drm_debug. Some of these are page-flips > and vblanks, and get called often. > > DYNAMIC_DEBUG (with CONFIG_JUMP_LABEL) is built to avoid this kind of > work, with NOOPd jump/callsites. > > This patchset is RFC because: > - it touches 2.5 subsystems: dyndbg, drm, tracefs (new events) > - dyndbg class support is built for drm, needs it for validation > - new api, used by drm > - big memory impact, with 5100 new pr-debug callsites. > - drm class bikeshedding opportunities > - others, names etc. Thanks a lot for keeping on pushing this! > > DYNAMIC_DEBUG: > > Adapt to directly represent 32 exclusive classes / categories. > All existing users get _CLASS_DFLT:31, reserving 0-30 for opt-in. > > dynamic_debug_register_classes(): Tells dyndbg that caller/client is > using .class_id's 0..N, and wants them exposed and manipulatable with > names: DRM_UT_KMS etc. > > Client invokes DYNAMIC_DEBUG_CLASSES to define the name->id map, > then registers it during its initialization. > > Then, when a dyndbg command-query has "class FOO": > > echo class DRM_UT_KMS +p > /proc/dynamic_debug/control > > ddebug_change() will 1st ddebug_validate_classname() for each module, > using its registered class-maps; only modules which know DRM_UT_KMS > will get those callsite adjustments. This "protects" each module's > class-id space, unlike "class 4" query syntax. > > Add bitmap support for: > echo 0x02 > /sys/module/drm/parameters/debug > > Add symbolic bitmap, because we have the class-names: > echo +DRM_UT_KMS,+DRM_UT_ATOMIC > /sys/module/drm/parameters/debug > > Add test_dynamic_debug, to prove out the API. > > which is (used 3x to prove class-id ranges): > - DYNAMIC_DEBUG_CLASSES(var, ... [3 class-name-literals each]) > - dynamic_debug_register_classes(var) > - dynamic_debug_unregister_classes(var) > also (6x): > +module_param_cb(<node-name>, ¶m_ops_dyndbg_classes, /[pt][123]_bitmap/, 0600); > > Bits 0,1,2 of each of the 6 bitmaps control the 3 named classes in > each of 3 groups, toggling their p,T bits respectively. > > RFC: > > dynamic_debug_register_classes() cannot act early enough to be in > effect at module-load. So this will not work as you'd reasonably > expect: > > modprobe test_dynamic_debug dyndbg='+pfm; class FOO +pfmlt' > > The 1st query:+pfm will be enabled during load, but in the 2nd query, > "class FOO" will be unknown at load time. Early class enablement > would be nice. DYNAMIC_DEBUG_CLASSES is a static initializer, which > is certainly early enough, but Im missing a trick, suggestions? So maybe I'm just totally overloading this work here so feel free to ignore or postpone, but: Could we do the dynamic_debug_register_classes() automatically at module load as a new special section? And then throw in a bit of kbuild so that in a given subsystem every driver gets the same class names by default and everything would just work, without having to sprinkle calls to dynamic_debug_register_classes() all over the place? That kbuild magic could then also insert all the boilerplate to make the module options work, or maybe you could push that all into the module loader and it would add these special options on its own (yay for more consistency across subsystems)? Also I think with that the early class stuff should be possible to fix, since you can make sure that the classes are all there (in the module loader code) before anything else gets done. A bit a special case but oh well. For the entire class approach, did you spot another subsystem that could benefit from this and maybe make a more solid case that this is something good? > Wildcarding on classname is possible, maybe useful: > > echo +DRM_UT_\* > /sys/module/drm/parameters/debug > > If contemplated in earnest, it should consider the difference between > "DRM_*" and "*_KMS", wrt observing across class hierarchies, as well > as decide whether that echo means 1st match, or all matching names. > > __pr_debug_cls(cls, fmt,...) is just for testing, drm doesnt need it. > > > DRM adaptation: > > Basically, these patches add another layer of macro indirection, which > by CONFIG_DRM_USE_DYNAMIC_DEBUG=y, wraps drm_*dbg() in dyndbg's callsite > Factory macro, and adds the new descriptor arg to the funcs. > > With these patches, drm.debugs appear as controllable *pr-dbg* callsites: > > [ 11.804352] dyndbg: register_classes: drm > [ 11.920715] dyndbg: 234 debug prints in module drm_kms_helper > [ 11.932135] dyndbg: 2 debug prints in module ttm > [ 11.936119] dyndbg: 8 debug prints in module video > [ 12.537543] dyndbg: 1756 debug prints in module i915 > [ 12.555045] dyndbg: register_classes: i915 > [ 12.666727] AMD-Vi: AMD IOMMUv2 functionality not available on this .. > [ 13.735310] dyndbg: 3859 debug prints in module amdgpu > > amdgpu's large count includes: > 582 direct uses/mentions of pr_debug > 43 defns of DC_LOG_*, which use either pr_debug or DRM_DEBUG_* > ~1000 uses of DC_LOG_* > 1116 uses of dml_print in drivers/gpu/drm/amd > 15 drm_dbg_\\w+ drivers/gpu/drm/amd > 273 DRM_DEBUG_\\w+ drivers/gpu/drm/amd > > i915 has: > 1072 drm_dbg_\\w+ drivers/gpu/drm/i915/ | wc -l > 200 DRM_DEBUG_\\w+ drivers/gpu/drm/i915/ > 46 pr_debug drivers/gpu/drm/i915/ > 144 gvt_dbg_\\w+ drivers/gpu/drm/i915/gvt, using pr_debug > > This impacts the data footprint, so everything new/drm is dependent on > DRM_USE_DYNAMIC_DEBUG=y. > > RFC for DRM: > > - decoration flags "fmlt" do not work on drm_*dbg(). > (drm_*dbg() dont use pr_debug, they *become* one flavor of them) > this could (should?) be added, and maybe tailored for drm. > some of the device prefixes are very long, a "d" flag could optionalize them. I'm lost what the fmlt decoration flags are? > - api use needs review wrt drm life-cycle. > enum drm_debug_category and DYNAMIC_DEBUG_CLASSES could be together? Hm if they're tied to module lifetime we should be good? Not sure what could go wrong here. > - class-names could stand review, perhaps extension > "drm:core:" etc have appeared (maybe just from me) > or a "plan" to look at it later Yeah it's been a bit sprawling. I'm kinda hoping that by firmly establishing dyndbg as the drm debug approach we can cut down for the need for ad-hoc flags a bit. > - i915 & amdgpu have pr_debugs (DC_LOG_*, gvt_dbg_*) that have > class-ish prefixes that are separate from, but similar to DRM_UT_*, > and could stand review and possible unification with reformed or > extended drm categories. Yeah drm is not entirely consistent with how exactly driver debug printing should be done. Another reason why I'm hoping that the kitchen sync with everything approach you're doing here could help unify things. > - the change to enum drm_debug_category from bitmask values to 0..31 > means that we foreclose this possiblility: > > drm_dbg(DRM_UT_CORE|DRM_UT_KMS, "wierd double-cat experiment"); Yeah no, that doesn't make much sense to me :-) > - nouveau has very few drm.debug calls, > has NV_DEBUG, VMM_DEBUG, nvkm_printk_, I havent looked deeply. Yeah see above. There's a pile more drivers (more on the armsoc side of things) which are quite big on the raw debug call approach. Cheers, Daniel > > DYNDBG/DRM -> TRACEFS > > My 1st try was motivated by Sean Paul's patch - DRM.trace: > https://patchwork.freedesktop.org/patch/445549/?series=78133&rev=5 > > Those used trace_printk, so were not good for upstream. > > Vincent Whitchurch's code: > https://lore.kernel.org/lkml/20200721141105.16034-1-vincent.whitchurch@axis.com/ > > added similar features, by sending printk:console events from dyndbg. > It met with a good reception from Steve Rostedt, so I re-started with > that. > > The biggest addition (from UI viewpoint) is 4 new trace-events, 2 each > from dyndbg (pr_debug, dev_dbg) and drm (drm_dbg, drm_dev_dbg); 2 have > dev, other 2 avoid storing nulls. Im unsure that 4 distinctions is > valuable, but it seemed most obvious to reflect them straight thru to > tracefs. > > RFC: the event/message formats are a bit of a mash-up; > > in /sys/kernel/tracing: > drm/drm_debug/format:print fmt: "%s", __get_str(msg) > drm/drm_devdbg/format:print fmt: "cat:%d, %s %s", \ > REC->drm_debug_category, dev_name(REC->dev), __get_str(msg) > > The 1st prints just the mesg itself, 2nd prints category as int; > it'd be better if DRM.class-name replaced (not just augmented) the > event-name "drm_devdbg" in the trace, is that possible ? > > dyndbg/prdbg/format: > print fmt: "%s.%s %s", REC->desc->modname, REC->desc->function, __get_str(msg) > dyndbg/devdbg/format: > print fmt: "%s.%s %s", REC->desc->modname, REC->desc->function, __get_str(msg) > > These add a prefix string similar to dyndbg's decorations, except they > don't use dyndbg's "fmlt" decoration flags. > > There are also 3 vblank trace-events already, > declared in: drivers/gpu/drm/drm_trace.h > 15:TRACE_EVENT(drm_vblank_event, > 35:TRACE_EVENT(drm_vblank_event_queued, > 52:TRACE_EVENT(drm_vblank_event_delivered, > > STATUS > > kernel-test-robot tested this patchset (on 5.18-rc6). > github:[jimc:blead] BUILD SUCCESS 6c59e52ac81dd81ac7da4522a5e15b7ac488d5b5 > May 15, 2022, 8:39 AM (1 day ago) > > > Ive been testing, mostly on virtme, mostly with this: > #!/bin/bash > > # test class FOO handling of dynamic-debug > > alias lmt='modprobe test_dynamic_debug dyndbg=+pmf' > alias rmt='rmmod test_dynamic_debug' > alias look='grep test_dynamic_debug /proc/dynamic_debug/control' > > lookfor() { > grep $1 /proc/dynamic_debug/control > } > > vx() { > echo $* > /sys/module/dynamic_debug/parameters/verbose > } > > # amdgpu has ~2200 pr-debugs (before drm-debug-on-dyndbg), > # use them to prove modprobe <mod> dyndbg=+p works > > test_param_dyndbg() { > > modprobe amdgpu dyndbg=+pfm > let count=$(grep =pmf /proc/dynamic_debug/control | grep amdgpu | wc -l) > > if [ $count -gt 200 ] ; then > echo amdgpu has $count pr-dbgs > return 0 > else > echo failed $count > return -1 > fi > } > out=$(test_param_dyndbg) > echo out:$out $? > [ $? -eq 0 ] || exit $? > > qry_cmd() { > echo "QCMD: $* >control" >&2 > echo $* > /proc/dynamic_debug/control > } > > # enable dyndbg tracing > dynable() { > grep -P \\d $SKT/events/dyndbg/{.,*}/enable > echo 1 > $SKT/events/dyndbg/enable > grep -P \\d $SKT/events/dyndbg/{.,*}/enable > } > > # enable drm tracing > drmable() { > grep -P \\d $SKT/events/drm/{.,*}/enable > echo 1 > $SKT/events/drm/enable > grep -P \\d $SKT/events/drm/{.,*}/enable > } > > function doit() { > cat /sys/module/test_dynamic_debug/parameters/do_prints > } > > # test class FOO behavior of test_dynamic_debug module > ttest_module__() { > flg=$1 > dmesg -C > modprobe test_dynamic_debug dyndbg=+pfm > doit > > for cls in FOO BAR BUZZ; do > qry_cmd module test_dynamic_debug class $cls $flg > doit > done > doit > > for cls in Foo Bar Buzz; do > qry_cmd module test_dynamic_debug class $cls $flg > doit > done > doit > > for cls in bing bong boom; do > qry_cmd module test_dynamic_debug class $cls $flg > doit > done > doit > > dmesg | grep class > } > > ttest_module() { > > ttest_module__ +p > ttest_module__ -p > > #ttest_module__ +T > #ttest_module__ -T > } > > #dynable > #drmable > > ttest_module > grep test_dyn /proc/dynamic_debug/control > > > # use/test bitmaps > > set_tddm_() { > val=$1; > knob=$2; > echo "TDDM: $val >$knob" >&2 > echo $val > /sys/module/test_dynamic_debug/parameters/$knob > cat /sys/module/test_dynamic_debug/parameters/$knob > } > > CLS_1="FOO -FOO +FOO -FOO BAR -BAR +BAR -BAR BUZZ -BUZZ +BUZZ -BUZZ" > CLS_2=" Foo Bar Buzz -Foo -Bar -Buzz +Foo +Bar +Buzz -Foo -Bar -Buzz" > CLS_3=" bing bong boom -bing -bong -boom +bing +bong +boom -bing -bong -boom" > > tddm_sysnode_classes__() { > targ=$1 > shift > cls=$* > for bitsym in $cls; > do > set_tddm_ $bitsym $targ > done > } > > # work all 3 sysfs bitmaps > > for sysnode in c1_syslog_bits c2_syslog_bits c3_syslog_bits; > do > for val in 0 1 2 4 8 0; > do > tddm_sysnode_classes__ $sysnode $val > done > done > > tddm_sysnode_classes__ c1_syslog_bits $CLS_1 > tddm_sysnode_classes__ c2_syslog_bits $CLS_2 > tddm_sysnode_classes__ c3_syslog_bits $CLS_3 > > echo "show unknown: c3-names on c1-knob" >&2 > tddm_sysnode_classes__ c1_trace_bits $CLS_3 > > echo "flags look inverted" >&2 > tddm_sysnode_classes__ c1_syslog_bits $CLS_1 > > CLS_1_=FOO,-FOO,+FOO,-FOO,BAR,-BAR,+BAR,-BAR,BUZZ,-BUZZ,+BUZZ,-BUZZ > CLS_2_=Foo,Bar,Buzz,-Foo,-Bar,-Buzz,+Foo,+Bar,+Buzz,-Foo,-Bar,-Buzz > # leading err doesnt wreck the rest > CLS_3_=,bing,bong,boom,-bing,-bong,-boom,+bing,+bong,+boom,-bing,-bong,-boom > > tddm_sysnode_classes__ c1_syslog_bits $CLS_1_ > tddm_sysnode_classes__ c2_syslog_bits $CLS_2_ > tddm_sysnode_classes__ c3_syslog_bits $CLS_3_ > > > Cc: Sean Paul <seanpaul@chromium.org> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: David Airlie <airlied@gmail.com> > Cc: Jani Nikula <jani.nikula@linux.intel.com> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> > Cc: Pekka Paalanen <ppaalanen@gmail.com> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > Cc: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Steven Rostedt <rostedt@goodmis.org> > > Jim Cromie (27): > dyndbg: fix static_branch manipulation > dyndbg: show both old and new in change-info > dyndbg: fix module.dyndbg handling > dyndbg: drop EXPORTed dynamic_debug_exec_queries > dyndbg: add exclusive class_id to pr_debug callsites > dyndbg: add dynamic_debug_(un)register_classes > dyndbg: validate class FOO on module > dyndbg: add drm.debug style bitmap support > Doc/dyndbg: document new class class_name query support > dyndbg: let query-modname override defaulting modname > dyndbg: support symbolic class-names in bitmap > dyndbg: change zero-or-one classes-map to maps list > dyndbg: add __pr_debug_cls(class, fmt, ...) > dyndbg: add test_dynamic_debug module > drm: POC drm on dyndbg - map class-names to drm_debug_category's > drm/print: POC drm on dyndbg - use bitmap > drm_print: condense enum drm_debug_category > drm_print: interpose drm_*dbg with forwarding macros > drm_print: wrap drm_*_dbg in dyndbg descriptor factory macro > drm_print: refine drm_debug_enabled for jump-label > drm_print: prefer bare printk KERN_DEBUG on generic fn > drm_print: add _ddebug desc to drm_*dbg prototypes > dyndbg: add _DPRINTK_FLAGS_ENABLED > dyndbg: add _DPRINTK_FLAGS_TRACE > dyndbg: add write-events-to-tracefs code > dyndbg: 4 new trace-events: pr_debug, dev_dbg, drm_{,dev}debug > dyndbg/drm: POC add tracebits sysfs-knob > > .../admin-guide/dynamic-debug-howto.rst | 12 + > MAINTAINERS | 1 + > drivers/gpu/drm/Kconfig | 12 + > drivers/gpu/drm/Makefile | 2 + > drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 3 + > drivers/gpu/drm/drm_drv.c | 5 + > drivers/gpu/drm/drm_print.c | 69 ++- > drivers/gpu/drm/i915/i915_module.c | 11 + > drivers/gpu/drm/nouveau/nouveau_drm.c | 4 + > include/drm/drm_drv.h | 26 + > include/drm/drm_print.h | 84 ++- > include/linux/dynamic_debug.h | 136 ++++- > include/trace/events/drm.h | 68 +++ > include/trace/events/dyndbg.h | 74 +++ > lib/Kconfig.debug | 11 + > lib/Makefile | 1 + > lib/dynamic_debug.c | 487 +++++++++++++++--- > lib/test_dynamic_debug.c | 172 +++++++ > 18 files changed, 1049 insertions(+), 129 deletions(-) > create mode 100644 include/trace/events/drm.h > create mode 100644 include/trace/events/dyndbg.h > create mode 100644 lib/test_dynamic_debug.c > > -- > 2.35.1 >
On Mon, Jun 06, 2022 at 08:59:36AM -0600, jim.cromie@gmail.com wrote: > On Wed, May 25, 2022 at 9:02 AM Daniel Vetter <daniel@ffwll.ch> wrote: > > > On Mon, May 16, 2022 at 04:56:13PM -0600, Jim Cromie wrote: > > > DRM.debug API is 23 macros, issuing 10 exclusive categories of debug > > > messages. By rough count, they are used 5140 times in the kernel. > > > These all call drm_dbg or drm_devdbg, which call drm_debug_enabled(), > > > which checks bits in global __drm_debug. Some of these are page-flips > > > and vblanks, and get called often. > > > > > > DYNAMIC_DEBUG (with CONFIG_JUMP_LABEL) is built to avoid this kind of > > > work, with NOOPd jump/callsites. > > > > > > This patchset is RFC because: > > > - it touches 2.5 subsystems: dyndbg, drm, tracefs (new events) > > > - dyndbg class support is built for drm, needs it for validation > > > - new api, used by drm > > > - big memory impact, with 5100 new pr-debug callsites. > > > - drm class bikeshedding opportunities > > > - others, names etc. > > > > Thanks a lot for keeping on pushing this! > > > > > > > > DYNAMIC_DEBUG: > > > > > > > > > RFC: > > > > > > dynamic_debug_register_classes() cannot act early enough to be in > > > effect at module-load. So this will not work as you'd reasonably > > > expect: > > > > > > modprobe test_dynamic_debug dyndbg='+pfm; class FOO +pfmlt' > > > > > > The 1st query:+pfm will be enabled during load, but in the 2nd query, > > > "class FOO" will be unknown at load time. Early class enablement > > > would be nice. DYNAMIC_DEBUG_CLASSES is a static initializer, which > > > is certainly early enough, but Im missing a trick, suggestions? > > > > So maybe I'm just totally overloading this work here so feel free to > > ignore or postpone, but: Could we do the dynamic_debug_register_classes() > > automatically at module load as a new special section? And then throw in a > > bit of kbuild so that in a given subsystem every driver gets the same > > class names by default and everything would just work, without having to > > sprinkle calls to dynamic_debug_register_classes() all over the place? > > > > This is now done; Ive added __dyndbg_classes section. > load_module() now grabs it from the .ko > and ddebug_add_module() attaches it to the module's ddebug_table record. > for builtins, dynamic_debug_init feeds the builtin class-maps to > ddebug_add_module > > bash-5.1# modprobe test_dynamic_debug dyndbg="class FOO +p" > [ 88.374722] dyndbg: class[0]: nm:test_dynamic_debug base:20 len:7 ty:1 > [ 88.375158] dyndbg: 0: EMERG > [ 88.375345] dyndbg: 1: DANGER > [ 88.375540] dyndbg: 2: ERROR > [ 88.375726] dyndbg: 3: WARNING > [ 88.375930] dyndbg: 4: NOTICE > [ 88.376130] dyndbg: 5: INFO > [ 88.376310] dyndbg: 6: DEBUG > [ 88.376499] dyndbg: class[1]: nm:test_dynamic_debug base:12 len:3 ty:1 > [ 88.376903] dyndbg: 0: ONE > [ 88.377079] dyndbg: 1: TWO > [ 88.377253] dyndbg: 2: THREE > [ 88.377441] dyndbg: class[2]: nm:test_dynamic_debug base:8 len:3 ty:0 > [ 88.377837] dyndbg: 0: bing > [ 88.378022] dyndbg: 1: bong > [ 88.378203] dyndbg: 2: boom > [ 88.378387] dyndbg: class[3]: nm:test_dynamic_debug base:4 len:3 ty:0 > [ 88.378800] dyndbg: 0: Foo > [ 88.378986] dyndbg: 1: Bar > [ 88.379167] dyndbg: 2: Buzz > [ 88.379348] dyndbg: class[4]: nm:test_dynamic_debug base:0 len:3 ty:0 > [ 88.379757] dyndbg: 0: FOO > [ 88.379938] dyndbg: 1: BAR > [ 88.380136] dyndbg: 2: BUZZ > [ 88.380410] dyndbg: module:test_dynamic_debug attached 5 classes > [ 88.380881] dyndbg: 24 debug prints in module test_dynamic_debug > [ 88.381315] dyndbg: module: test_dynamic_debug dyndbg="class FOO +p" > [ 88.381714] dyndbg: query 0: "class FOO +p" mod:test_dynamic_debug > [ 88.382109] dyndbg: split into words: "class" "FOO" "+p" > [ 88.382445] dyndbg: op='+' > [ 88.382616] dyndbg: flags=0x1 > [ 88.382802] dyndbg: *flagsp=0x1 *maskp=0xffffffff > [ 88.383101] dyndbg: parsed: func="" file="" module="test_dynamic_debug" > format="" lineno=0-0 class=FOO > [ 88.383740] dyndbg: applied: func="" file="" module="test_dynamic_debug" > format="" lineno=0-0 class=FOO > [ 88.384324] dyndbg: processed 1 queries, with 2 matches, 0 errs > bash-5.1# > > so its working at module-load time. Awesome! > > For the entire class approach, did you spot another subsystem that could > > benefit from this and maybe make a more solid case that this is something > > good? > > > > I had been working on the premise that ~4k drm*dbg callsites was a good > case. Oh I'm happy with just drm, but occasionally we've done stuff in drm that the wider kernel community found a bit silly. So bit more acks/validation from outside the dri-devel echo chamber would be great, whatever form it is. > verbosity-levels - with x<y logic instead of x==y is what's currently > missing. > > the next revision adds something, which "kinda works". > But I think I'll rip it out, and do this simpler approach instead: > > implement a verbose/levels param & callback, which takes > > echo 3 > /sys/module/foo/parameters/debug_verbosity > > and effectively does > > echo <<EOQRY > /proc/dynamic_debug/control > module foo class V1 +p > module foo class V2 +p > module foo class V3 +p > module foo class V4 -p > module foo class V5 -p > module foo class V6 -p > module foo class V7 -p > module foo class V8 -p > EOQRY > > since only real +/-p changes incur kernel-patching costs, > the remaining overheads are minimal. > > > > RFC for DRM: > > > > - decoration flags "fmlt" do not work on drm_*dbg(). > > (drm_*dbg() dont use pr_debug, they *become* one flavor of them) > > this could (should?) be added, and maybe tailored for drm. > > some of the device prefixes are very long, a "d" flag could optionalize > them. > > I'm lost what the fmlt decoration flags are? > > > The flags are:: > > p enables the pr_debug() callsite. > f Include the function name in the printed message > l Include line number in the printed message > m Include module name in the printed message > t Include thread ID in messages not generated from interrupt context > _ No flags are set. (Or'd with others on input) > > > the fmlt flags add a "decoration" prefix to enabled/printed log messages Oh I was just confused and thought fmlt was some special format thing, and not just the list of letters that wond work due to the implementation. If you havent, maybe just spell the above list out (like you do here) in the docs? > > - api use needs review wrt drm life-cycle. > > > enum drm_debug_category and DYNAMIC_DEBUG_CLASSES could be together? > > > > Hm if they're tied to module lifetime we should be good? Not sure what > > could go wrong here. > > > > > with the new __section, "life-cycle" doesnt really pertain. > the new issue is how the class-maps are shared across the subsystem; > the current class-maps list for each module will probably break; > a list item cannot be on N different lists of different modules. > Altering the list-items to ref the class-map (not contain it) should solve > the problem. > > > > > > > - class-names could stand review, perhaps extension > > > "drm:core:" etc have appeared (maybe just from me) > > > or a "plan" to look at it later > > > > Yeah it's been a bit sprawling. I'm kinda hoping that by firmly > > establishing dyndbg as the drm debug approach we can cut down for the need > > for ad-hoc flags a bit. > > > > yeah thats why I kept the DRM_UT_* names. > OTOH - the symbolic names patch exposes the choices, > which locks the names as API ?? Yeah that part is fine. It's more because the flags was the only thing we ever had, any debug need was solved with them. With dyndbg we should have a lot more and a lot more precise options for handling this. So I'm not worried about the flags and their names per-se, more that we had some pressure to add more flags for specific files and libraries. Dyndbg should give us a much more powerful tool for these problems. > > > - i915 & amdgpu have pr_debugs (DC_LOG_*, gvt_dbg_*) that have > > > class-ish prefixes that are separate from, but similar to DRM_UT_*, > > > and could stand review and possible unification with reformed or > > > extended drm categories. > > > > Yeah drm is not entirely consistent with how exactly driver debug printing > > should be done. Another reason why I'm hoping that the kitchen sync with > > everything approach you're doing here could help unify things. > > > > > the decoration flags can help here; they loosely/precisely describe > the elements of most/all the current debug format-prefix variations. > So case by case, the ad-hoc variations should map onto these flags, > > The flags allow selectively dropping the prefix info from some of the log > entries, > after you've seen the module name and function a dozen times, > it's helpful to reduce screen clutter. > > It might make sense to add a new flag for device, > so that dev_dbg() flavors can shorten-or-skip the longer device strings, > maybe some drm specific flavors. > > > > > > > > - the change to enum drm_debug_category from bitmask values to 0..31 > > > means that we foreclose this possiblility: > > > > > > drm_dbg(DRM_UT_CORE|DRM_UT_KMS, "wierd double-cat experiment"); > > > > Yeah no, that doesn't make much sense to me :-) > > > > no chuckles for the schrodinger's cat joke ? > (maybe "yeah no" is the artful superpositional reply, I just caught :) > > > > > - nouveau has very few drm.debug calls, > > > has NV_DEBUG, VMM_DEBUG, nvkm_printk_, I havent looked deeply. > > > > > nouveau has like levels, man .. > test_dynamic_debug implements its priority-style names as a POC > > patch 18 converts nvkm_debug/trace to use dev_dbg instead of dev_info > it probably could adapt to use drm_devdbg > > > > > > Yeah see above. There's a pile more drivers (more on the armsoc side of > > things) which are quite big on the raw debug call approach. > > > > > LOW, MID, HI has been proposed at least once wrt dyndbg. > that probably fits well with current disjoint classes. > level/verbose classes should be practical too, as described above. > > NB: The symbolic names should also work > > echo +MID > /sys/module/foobar/parameters/debug_verbosity > > though theres some ambiguity with > > echo -V3 > /sys/module/foobar/parameters/debug_verbosity > > that should turn off V4,5,6, > but what about V1,2 ? > it could leave them alone (whatever their previous settings are) > > anyway, lkp-robot and igt-trybot should be grinding on the latest patchset > soon, > I'll send it after I fix whatever breaks. Awesome, like I said I'm a bit drowned in everything, but I'm really happy you're pushing this! -Daniel > > > > > Cheers, Daniel > > > > thanks, > Jim
DRM.debug API is 23 macros, issuing 10 exclusive categories of debug messages. By rough count, they are used 5140 times in the kernel. These all call drm_dbg or drm_devdbg, which call drm_debug_enabled(), which checks bits in global __drm_debug. Some of these are page-flips and vblanks, and get called often. DYNAMIC_DEBUG (with CONFIG_JUMP_LABEL) is built to avoid this kind of work, with NOOPd jump/callsites. This patchset is RFC because: - it touches 2.5 subsystems: dyndbg, drm, tracefs (new events) - dyndbg class support is built for drm, needs it for validation - new api, used by drm - big memory impact, with 5100 new pr-debug callsites. - drm class bikeshedding opportunities - others, names etc. DYNAMIC_DEBUG: Adapt to directly represent 32 exclusive classes / categories. All existing users get _CLASS_DFLT:31, reserving 0-30 for opt-in. dynamic_debug_register_classes(): Tells dyndbg that caller/client is using .class_id's 0..N, and wants them exposed and manipulatable with names: DRM_UT_KMS etc. Client invokes DYNAMIC_DEBUG_CLASSES to define the name->id map, then registers it during its initialization. Then, when a dyndbg command-query has "class FOO": echo class DRM_UT_KMS +p > /proc/dynamic_debug/control ddebug_change() will 1st ddebug_validate_classname() for each module, using its registered class-maps; only modules which know DRM_UT_KMS will get those callsite adjustments. This "protects" each module's class-id space, unlike "class 4" query syntax. Add bitmap support for: echo 0x02 > /sys/module/drm/parameters/debug Add symbolic bitmap, because we have the class-names: echo +DRM_UT_KMS,+DRM_UT_ATOMIC > /sys/module/drm/parameters/debug Add test_dynamic_debug, to prove out the API. which is (used 3x to prove class-id ranges): - DYNAMIC_DEBUG_CLASSES(var, ... [3 class-name-literals each]) - dynamic_debug_register_classes(var) - dynamic_debug_unregister_classes(var) also (6x): +module_param_cb(<node-name>, ¶m_ops_dyndbg_classes, /[pt][123]_bitmap/, 0600); Bits 0,1,2 of each of the 6 bitmaps control the 3 named classes in each of 3 groups, toggling their p,T bits respectively. RFC: dynamic_debug_register_classes() cannot act early enough to be in effect at module-load. So this will not work as you'd reasonably expect: modprobe test_dynamic_debug dyndbg='+pfm; class FOO +pfmlt' The 1st query:+pfm will be enabled during load, but in the 2nd query, "class FOO" will be unknown at load time. Early class enablement would be nice. DYNAMIC_DEBUG_CLASSES is a static initializer, which is certainly early enough, but Im missing a trick, suggestions? Wildcarding on classname is possible, maybe useful: echo +DRM_UT_\* > /sys/module/drm/parameters/debug If contemplated in earnest, it should consider the difference between "DRM_*" and "*_KMS", wrt observing across class hierarchies, as well as decide whether that echo means 1st match, or all matching names. __pr_debug_cls(cls, fmt,...) is just for testing, drm doesnt need it. DRM adaptation: Basically, these patches add another layer of macro indirection, which by CONFIG_DRM_USE_DYNAMIC_DEBUG=y, wraps drm_*dbg() in dyndbg's callsite Factory macro, and adds the new descriptor arg to the funcs. With these patches, drm.debugs appear as controllable *pr-dbg* callsites: [ 11.804352] dyndbg: register_classes: drm [ 11.920715] dyndbg: 234 debug prints in module drm_kms_helper [ 11.932135] dyndbg: 2 debug prints in module ttm [ 11.936119] dyndbg: 8 debug prints in module video [ 12.537543] dyndbg: 1756 debug prints in module i915 [ 12.555045] dyndbg: register_classes: i915 [ 12.666727] AMD-Vi: AMD IOMMUv2 functionality not available on this .. [ 13.735310] dyndbg: 3859 debug prints in module amdgpu amdgpu's large count includes: 582 direct uses/mentions of pr_debug 43 defns of DC_LOG_*, which use either pr_debug or DRM_DEBUG_* ~1000 uses of DC_LOG_* 1116 uses of dml_print in drivers/gpu/drm/amd 15 drm_dbg_\\w+ drivers/gpu/drm/amd 273 DRM_DEBUG_\\w+ drivers/gpu/drm/amd i915 has: 1072 drm_dbg_\\w+ drivers/gpu/drm/i915/ | wc -l 200 DRM_DEBUG_\\w+ drivers/gpu/drm/i915/ 46 pr_debug drivers/gpu/drm/i915/ 144 gvt_dbg_\\w+ drivers/gpu/drm/i915/gvt, using pr_debug This impacts the data footprint, so everything new/drm is dependent on DRM_USE_DYNAMIC_DEBUG=y. RFC for DRM: - decoration flags "fmlt" do not work on drm_*dbg(). (drm_*dbg() dont use pr_debug, they *become* one flavor of them) this could (should?) be added, and maybe tailored for drm. some of the device prefixes are very long, a "d" flag could optionalize them. - api use needs review wrt drm life-cycle. enum drm_debug_category and DYNAMIC_DEBUG_CLASSES could be together? - class-names could stand review, perhaps extension "drm:core:" etc have appeared (maybe just from me) or a "plan" to look at it later - i915 & amdgpu have pr_debugs (DC_LOG_*, gvt_dbg_*) that have class-ish prefixes that are separate from, but similar to DRM_UT_*, and could stand review and possible unification with reformed or extended drm categories. - the change to enum drm_debug_category from bitmask values to 0..31 means that we foreclose this possiblility: drm_dbg(DRM_UT_CORE|DRM_UT_KMS, "wierd double-cat experiment"); - nouveau has very few drm.debug calls, has NV_DEBUG, VMM_DEBUG, nvkm_printk_, I havent looked deeply. DYNDBG/DRM -> TRACEFS My 1st try was motivated by Sean Paul's patch - DRM.trace: https://patchwork.freedesktop.org/patch/445549/?series=78133&rev=5 Those used trace_printk, so were not good for upstream. Vincent Whitchurch's code: https://lore.kernel.org/lkml/20200721141105.16034-1-vincent.whitchurch@axis.com/ added similar features, by sending printk:console events from dyndbg. It met with a good reception from Steve Rostedt, so I re-started with that. The biggest addition (from UI viewpoint) is 4 new trace-events, 2 each from dyndbg (pr_debug, dev_dbg) and drm (drm_dbg, drm_dev_dbg); 2 have dev, other 2 avoid storing nulls. Im unsure that 4 distinctions is valuable, but it seemed most obvious to reflect them straight thru to tracefs. RFC: the event/message formats are a bit of a mash-up; in /sys/kernel/tracing: drm/drm_debug/format:print fmt: "%s", __get_str(msg) drm/drm_devdbg/format:print fmt: "cat:%d, %s %s", \ REC->drm_debug_category, dev_name(REC->dev), __get_str(msg) The 1st prints just the mesg itself, 2nd prints category as int; it'd be better if DRM.class-name replaced (not just augmented) the event-name "drm_devdbg" in the trace, is that possible ? dyndbg/prdbg/format: print fmt: "%s.%s %s", REC->desc->modname, REC->desc->function, __get_str(msg) dyndbg/devdbg/format: print fmt: "%s.%s %s", REC->desc->modname, REC->desc->function, __get_str(msg) These add a prefix string similar to dyndbg's decorations, except they don't use dyndbg's "fmlt" decoration flags. There are also 3 vblank trace-events already, declared in: drivers/gpu/drm/drm_trace.h 15:TRACE_EVENT(drm_vblank_event, 35:TRACE_EVENT(drm_vblank_event_queued, 52:TRACE_EVENT(drm_vblank_event_delivered, STATUS kernel-test-robot tested this patchset (on 5.18-rc6). github:[jimc:blead] BUILD SUCCESS 6c59e52ac81dd81ac7da4522a5e15b7ac488d5b5 May 15, 2022, 8:39 AM (1 day ago) Ive been testing, mostly on virtme, mostly with this: #!/bin/bash # test class FOO handling of dynamic-debug alias lmt='modprobe test_dynamic_debug dyndbg=+pmf' alias rmt='rmmod test_dynamic_debug' alias look='grep test_dynamic_debug /proc/dynamic_debug/control' lookfor() { grep $1 /proc/dynamic_debug/control } vx() { echo $* > /sys/module/dynamic_debug/parameters/verbose } # amdgpu has ~2200 pr-debugs (before drm-debug-on-dyndbg), # use them to prove modprobe <mod> dyndbg=+p works test_param_dyndbg() { modprobe amdgpu dyndbg=+pfm let count=$(grep =pmf /proc/dynamic_debug/control | grep amdgpu | wc -l) if [ $count -gt 200 ] ; then echo amdgpu has $count pr-dbgs return 0 else echo failed $count return -1 fi } out=$(test_param_dyndbg) echo out:$out $? [ $? -eq 0 ] || exit $? qry_cmd() { echo "QCMD: $* >control" >&2 echo $* > /proc/dynamic_debug/control } # enable dyndbg tracing dynable() { grep -P \\d $SKT/events/dyndbg/{.,*}/enable echo 1 > $SKT/events/dyndbg/enable grep -P \\d $SKT/events/dyndbg/{.,*}/enable } # enable drm tracing drmable() { grep -P \\d $SKT/events/drm/{.,*}/enable echo 1 > $SKT/events/drm/enable grep -P \\d $SKT/events/drm/{.,*}/enable } function doit() { cat /sys/module/test_dynamic_debug/parameters/do_prints } # test class FOO behavior of test_dynamic_debug module ttest_module__() { flg=$1 dmesg -C modprobe test_dynamic_debug dyndbg=+pfm doit for cls in FOO BAR BUZZ; do qry_cmd module test_dynamic_debug class $cls $flg doit done doit for cls in Foo Bar Buzz; do qry_cmd module test_dynamic_debug class $cls $flg doit done doit for cls in bing bong boom; do qry_cmd module test_dynamic_debug class $cls $flg doit done doit dmesg | grep class } ttest_module() { ttest_module__ +p ttest_module__ -p #ttest_module__ +T #ttest_module__ -T } #dynable #drmable ttest_module grep test_dyn /proc/dynamic_debug/control # use/test bitmaps set_tddm_() { val=$1; knob=$2; echo "TDDM: $val >$knob" >&2 echo $val > /sys/module/test_dynamic_debug/parameters/$knob cat /sys/module/test_dynamic_debug/parameters/$knob } CLS_1="FOO -FOO +FOO -FOO BAR -BAR +BAR -BAR BUZZ -BUZZ +BUZZ -BUZZ" CLS_2=" Foo Bar Buzz -Foo -Bar -Buzz +Foo +Bar +Buzz -Foo -Bar -Buzz" CLS_3=" bing bong boom -bing -bong -boom +bing +bong +boom -bing -bong -boom" tddm_sysnode_classes__() { targ=$1 shift cls=$* for bitsym in $cls; do set_tddm_ $bitsym $targ done } # work all 3 sysfs bitmaps for sysnode in c1_syslog_bits c2_syslog_bits c3_syslog_bits; do for val in 0 1 2 4 8 0; do tddm_sysnode_classes__ $sysnode $val done done tddm_sysnode_classes__ c1_syslog_bits $CLS_1 tddm_sysnode_classes__ c2_syslog_bits $CLS_2 tddm_sysnode_classes__ c3_syslog_bits $CLS_3 echo "show unknown: c3-names on c1-knob" >&2 tddm_sysnode_classes__ c1_trace_bits $CLS_3 echo "flags look inverted" >&2 tddm_sysnode_classes__ c1_syslog_bits $CLS_1 CLS_1_=FOO,-FOO,+FOO,-FOO,BAR,-BAR,+BAR,-BAR,BUZZ,-BUZZ,+BUZZ,-BUZZ CLS_2_=Foo,Bar,Buzz,-Foo,-Bar,-Buzz,+Foo,+Bar,+Buzz,-Foo,-Bar,-Buzz # leading err doesnt wreck the rest CLS_3_=,bing,bong,boom,-bing,-bong,-boom,+bing,+bong,+boom,-bing,-bong,-boom tddm_sysnode_classes__ c1_syslog_bits $CLS_1_ tddm_sysnode_classes__ c2_syslog_bits $CLS_2_ tddm_sysnode_classes__ c3_syslog_bits $CLS_3_ Cc: Sean Paul <seanpaul@chromium.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Airlie <airlied@gmail.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Pekka Paalanen <ppaalanen@gmail.com> Cc: Rob Clark <robdclark@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Steven Rostedt <rostedt@goodmis.org> Jim Cromie (27): dyndbg: fix static_branch manipulation dyndbg: show both old and new in change-info dyndbg: fix module.dyndbg handling dyndbg: drop EXPORTed dynamic_debug_exec_queries dyndbg: add exclusive class_id to pr_debug callsites dyndbg: add dynamic_debug_(un)register_classes dyndbg: validate class FOO on module dyndbg: add drm.debug style bitmap support Doc/dyndbg: document new class class_name query support dyndbg: let query-modname override defaulting modname dyndbg: support symbolic class-names in bitmap dyndbg: change zero-or-one classes-map to maps list dyndbg: add __pr_debug_cls(class, fmt, ...) dyndbg: add test_dynamic_debug module drm: POC drm on dyndbg - map class-names to drm_debug_category's drm/print: POC drm on dyndbg - use bitmap drm_print: condense enum drm_debug_category drm_print: interpose drm_*dbg with forwarding macros drm_print: wrap drm_*_dbg in dyndbg descriptor factory macro drm_print: refine drm_debug_enabled for jump-label drm_print: prefer bare printk KERN_DEBUG on generic fn drm_print: add _ddebug desc to drm_*dbg prototypes dyndbg: add _DPRINTK_FLAGS_ENABLED dyndbg: add _DPRINTK_FLAGS_TRACE dyndbg: add write-events-to-tracefs code dyndbg: 4 new trace-events: pr_debug, dev_dbg, drm_{,dev}debug dyndbg/drm: POC add tracebits sysfs-knob .../admin-guide/dynamic-debug-howto.rst | 12 + MAINTAINERS | 1 + drivers/gpu/drm/Kconfig | 12 + drivers/gpu/drm/Makefile | 2 + drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 3 + drivers/gpu/drm/drm_drv.c | 5 + drivers/gpu/drm/drm_print.c | 69 ++- drivers/gpu/drm/i915/i915_module.c | 11 + drivers/gpu/drm/nouveau/nouveau_drm.c | 4 + include/drm/drm_drv.h | 26 + include/drm/drm_print.h | 84 ++- include/linux/dynamic_debug.h | 136 ++++- include/trace/events/drm.h | 68 +++ include/trace/events/dyndbg.h | 74 +++ lib/Kconfig.debug | 11 + lib/Makefile | 1 + lib/dynamic_debug.c | 487 +++++++++++++++--- lib/test_dynamic_debug.c | 172 +++++++ 18 files changed, 1049 insertions(+), 129 deletions(-) create mode 100644 include/trace/events/drm.h create mode 100644 include/trace/events/dyndbg.h create mode 100644 lib/test_dynamic_debug.c