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[24.9.77.57]) by smtp.googlemail.com with ESMTPSA id t5sm2612315ilp.8.2021.11.11.14.02.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Nov 2021 14:02:12 -0800 (PST) From: Jim Cromie To: jbaron@akamai.com, 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 Cc: 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, jim.cromie@gmail.com Subject: [PATCH v10 00/10 RESEND] use DYNAMIC_DEBUG to implement DRM.debug & DRM.trace Date: Thu, 11 Nov 2021 15:01:56 -0700 Message-Id: <20211111220206.121610-1-jim.cromie@gmail.com> X-Mailer: git-send-email 2.33.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi Jason, Greg, DRM-everyone, everyone, resend to add more people, after rebasing on master to pick up 306589856399 drm/print: Add deprecation notes to DRM_...() functions This patchset has 3 separate but related parts: 1. DEFINE_DYNAMIC_DEBUG_BITGRPS macro [patch 1/10] Declares DRM.debug style bitmap, bits control pr_debugs by matching formats Adds callback to translate bits to $cmd > dynamic_debug/control This could obsolete EXPORT(dynamic_debug_exec_queries) not included. /* anticipated_usage */ static struct dyndbg_desc drm_categories_map[] = { [0] = { DRM_DBG_CAT_CORE }, [1] = { DRM_DBG_CAT_DRIVER }, [2] = { DRM_DBG_CAT_KMS }, [3] = { DRM_DBG_CAT_PRIME }, ... }; DEFINE_DYNAMIC_DEBUG_BITGRPS(debug, __drm_debug, " bits control drm.debug categories ", drm_categories_map); Please consider this patch for -next/now/current: - new interface, new code, no users to break - allows DRM folks to consider in earnest. - api bikeshedding to do ? struct dyndbg_desc isnt that great a name, others too probably. 2. use (1) to reimplement drm.debug [patches 3-7]: 1st in amdgpu & i915 to control existing pr_debugs by their formats POC for (1) then in drm-print, for all drm.debug API users has kernel-footprint impact: amdgpu has ~3k pr_debugs. (120kb callsite data) i915.ko has ~2k avoids drm_debug_enabled(), gives NOOP savings & new flexibility. changes drm.debug categories from enum to format-prefix-string alters in-log format to include the format-prefix-string Daniel Vetter liked this at -v3 https://lore.kernel.org/lkml/YPbPvm%2FxcBlTK1wq@phenom.ffwll.local/ Im sure Ive (still) missed stuff. 3. separately, Sean Paul proposed: drm.trace to mirror drm.debug to tracefs https://patchwork.freedesktop.org/series/78133/ He argues: tracefs is fast/lightweight compared to syslog independent selection (of drm categories) to tracefs gives tailored traffic w.o flooding syslog ISTM he's correct. So it follows that write-to-tracefs is also a good feature for dyndbg, where its then available for all pr_debug users, including all of drm, on a per-site basis, via echo +T >control. (iff CONFIG_TRACING). So basically, I borg'd his: [patch 14/14] drm/print: Add tracefs support to the drm logging helpers Then I added a T flag, so it can be toggled from shell: # turn on all drm's pr_debug --> tracefs echo module drm +T > /proc/dynamic_debug/control It appears to just work: (RFC) The instance name is a placeholder, per-module subdirs kinda fits the tracefs pattern, but full mod/file-basename/function/line feels like overkill, mod/basename-func.line would flatten it nicely. RFC. [root@gandalf dyndbg-tracefs]# pwd /sys/kernel/tracing/instances/dyndbg-tracefs [root@gandalf dyndbg-tracefs]# echo 1 > /sys/module/drm/parameters/trace [root@gandalf dyndbg-tracefs]# head -n16 trace | sed -e 's/^#//' tracer: nop entries-in-buffer/entries-written: 405/405 #P:24 _-----=> irqs-off / _----=> need-resched | / _---=> hardirq/softirq || / _--=> preempt-depth ||| / _-=> migrate-disable |||| / delay TASK-PID CPU# ||||| TIMESTAMP FUNCTION | | | ||||| | | <...>-2254 [000] ..... 7040.894352: __dynamic_pr_debug: drm:core: comm="gnome-shel:cs0" pid=2254, dev=0xe200, auth=1, AMDGPU_CS <...>-2207 [015] ..... 7040.894654: __dynamic_pr_debug: drm:core: comm="gnome-shell" pid=2207, dev=0xe200, auth=1, DRM_IOCTL_MODE_ADDFB2 <...>-2207 [015] ..... 7040.995403: __dynamic_pr_debug: drm:core: comm="gnome-shell" pid=2207, dev=0xe200, auth=1, DRM_IOCTL_MODE_RMFB <...>-2207 [015] ..... 7040.995413: __dynamic_pr_debug: drm:core: OBJ ID: 121 (2) This is the pr-debug doing most of that logging: (from dynamic_debug/control) drivers/gpu/drm/drm_ioctl.c:866 [drm]drm_ioctl =T "drm:core: comm=\042%s\042 pid=%d, dev=0x%lx, auth=%d, %s\012" Turning on decoration flags changes the trace: echo module drm format drm:core: +mflt > /proc/dynamic_debug/control TASK-PID CPU# ||||| TIMESTAMP FUNCTION | | | ||||| | | <...>-2254 [003] ..... 15980.936660: __dynamic_pr_debug: [2254] drm:drm_ioctl:866: drm:core: comm="gnome-shel:cs0" pid=2254, dev=0xe200, auth=1, AMDGPU_CS <...>-2207 [015] ..... 15980.936966: __dynamic_pr_debug: [2207] drm:drm_ioctl:866: drm:core: comm="gnome-shell" pid=2207, dev=0xe200, auth=1, DRM_IOCTL_MODE_ADDFB2 <...>-2207 [015] ..... 15981.037727: __dynamic_pr_debug: [2207] drm:drm_ioctl:866: drm:core: comm="gnome-shell" pid=2207, dev=0xe200, auth=1, DRM_IOCTL_MODE_RMFB <...>-2207 [015] ..... 15981.037739: __dynamic_pr_debug: [2207] drm:drm_mode_object_put:195: drm:core: OBJ ID: 124 (2) <...>-2207 [015] ..... 15981.037742: __dynamic_pr_debug: [2207] drm:drm_mode_object_put:195: drm:core: OBJ ID: 124 (1) The FUNCTION could stand tweaking (to match the callsite in the control file, cited above), or perhaps replaced by the 'mfl' decorations; the 't' flag is redundant for trace. Meh. SELFTEST A previous version of this patchset added test_dynamic_debug.ko, but it relied upon code I ripped out when I made tracefs available by default (without modules having to register 1st). So it fails 10/29 tests, which counted +T sites executed, via side effect. TODO: userspace selftest # to set expected tracing activity echo module test_dynamic_debug function do_debugging +T > control # run do_debugging function (todo: add sysfs knob) echo 2 > /sys/module/test-dynamic-debug/parameters/run_me If thats wrapped in the right trace_on, trace_pipe, etc incantations, the +T enabled pr_debugs in do_debugging() can be counted, compared against expectations, and passed or failed. change since v9: . patch confict against drm-misc resolved . s/CATEGORIES/BITGRPS/ in 1/10 - keep name generic: bitmap + groups . CATEGORIES is drm term, use it there only . fix api friction wrt drm.trace knob 2 separate macros: DEFINE_DYNAMIC_DEBUG_{LOG,TRACE}_GROUPS - JBaron v9: https://patchwork.freedesktop.org/series/96327/ v8: https://patchwork.freedesktop.org/series/93914/ https://lore.kernel.org/lkml/20210915163957.2949166-1-jim.cromie@gmail.com/ The major change since v8 is that +T now works for all users, if CONFIG_TRACING=y, otherwise it complains/errors. SUMMARY - drm as dyndbg user adds almost 9k callsites to kernel running this patchset substantial footprint substantial source of pr-debug-trace events (not all, but some useful) [jimc@gandalf wk-next]$ wc /proc/dynamic_debug/control 8927 71062 1099699 /proc/dynamic_debug/control [jimc@gandalf wk-next]$ uname -a Linux gandalf 5.15.0-rh2-12144-g5d5db04dfb0c #3 SMP PREEMPT Thu Nov 11 10:5 - pr_debug as event provider using exported trace_array_printk cheap with JUMP_LABEL precise, ad-hoc or organized callsite enablement callsite descriptor is in its interface, so are VARARGS inspectable, extensible wo api churn, iff trace_array_printk can do it. Jim Cromie (10): dyndbg: add DEFINE_DYNAMIC_DEBUG_BITGRPS macro and callbacks drm: fix doc grammar amdgpu: use dyndbg.BITGRPS to control existing pr_debugs i915/gvt: trim spaces from pr_debug "gvt: core:" prefixes i915/gvt: use dyndbg.BITGRPS for existing pr_debugs drm_print: add choice to use dynamic debug in drm-debug drm_print: instrument drm_debug_enabled dyndbg: add print-to-tracefs, selftest with it - RFC dyndbg: create DEFINE_DYNAMIC_DEBUG_LOG|TRACE_GROUPS drm: use DEFINE_DYNAMIC_DEBUG_TRACE_GROUPS in 3 places .../admin-guide/dynamic-debug-howto.rst | 7 +- MAINTAINERS | 1 + drivers/gpu/drm/Kconfig | 26 ++ drivers/gpu/drm/Makefile | 2 + drivers/gpu/drm/amd/amdgpu/Makefile | 2 + .../gpu/drm/amd/display/dc/core/dc_debug.c | 55 ++++- drivers/gpu/drm/drm_print.c | 62 +++-- drivers/gpu/drm/i915/Makefile | 2 + drivers/gpu/drm/i915/gvt/debug.h | 18 +- drivers/gpu/drm/i915/intel_gvt.c | 47 ++++ include/drm/drm_drv.h | 2 +- include/drm/drm_print.h | 182 +++++++++++--- include/linux/dynamic_debug.h | 88 ++++++- lib/Kconfig.debug | 11 + lib/Makefile | 1 + lib/dynamic_debug.c | 203 ++++++++++++++-- lib/test_dynamic_debug.c | 222 ++++++++++++++++++ 17 files changed, 843 insertions(+), 88 deletions(-) create mode 100644 lib/test_dynamic_debug.c -- 2.31.1