From: Jim Cromie Date: Mon, 12 Sep 2022 05:28:50 +0000 (-0600) Subject: drm_print: optimize drm_debug_enabled for jump-label X-Git-Tag: v6.1-rc5~263^2~6 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6ce6fae8453687e39e564dc15b6142fe79d76ad5;p=platform%2Fkernel%2Flinux-starfive.git drm_print: optimize drm_debug_enabled for jump-label When CONFIG_DRM_USE_DYNAMIC_DEBUG=y, the drm.debug API (a macro stack, calling _+drm_*dbg() eventually) invokes a dyndbg Factory macro to create a descriptor for each callsite, thus making them individually >control-able. In this case, the calls to _drm_*dbg are unreachable unless the callsite is enabled. So those calls can short-circuit their early do-nothing returns. Provide and use __drm_debug_enabled(), to do this when config'd, or the _raw flags-check otherwize. And since dyndbg is in use, lets also instrument the remaining users of drm_debug_enabled, by wrapping the _raw in a macro with a: pr_debug("todo: is this frequent enough to optimize ?\n"); For CONFIG_DRM_USE_DYNAMIC_DEBUG=n, do no site instrumenting at all, since JUMP_LABEL might be off, and we don't want to make work. With drm, amdgpu, i915, nouveau loaded, heres remaining uses of drm_debug_enabled(), which costs ~1.5kb data to control the pr_debug("todo:..")s. Some of those uses might be ok to use __drm_debug_enabled() by inspection, others might warrant conversion to use dyndbg Factory macros, and that would want callrate data to estimate the savings possible. TBH, any remaining savings are probably small; drm.debug covers the vast bulk of the uses. Maybe "vblank" is the exception. :#> grep todo /proc/dynamic_debug/control | wc 21 168 2357 :#> grep todo /proc/dynamic_debug/control drivers/gpu/drm/drm_edid_load.c:178 [drm]edid_load =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/drm_vblank.c:410 [drm]drm_crtc_accurate_vblank_count =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/drm_vblank.c:787 [drm]drm_crtc_vblank_helper_get_vblank_timestamp_internal =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/drm_vblank.c:1491 [drm]drm_vblank_restore =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/drm_vblank.c:1433 [drm]drm_vblank_enable =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/drm_plane.c:2168 [drm]drm_mode_setplane =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/display/drm_dp_mst_topology.c:1359 [drm_display_helper]drm_dp_mst_wait_tx_reply =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/display/drm_dp_mst_topology.c:2864 [drm_display_helper]process_single_tx_qlock =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/display/drm_dp_mst_topology.c:2909 [drm_display_helper]drm_dp_queue_down_tx =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/display/drm_dp_mst_topology.c:1686 [drm_display_helper]drm_dp_mst_update_slots =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_dp.c:1111 [i915]intel_dp_print_rates =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_backlight.c:5434 [i915]cnp_enable_backlight =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_backlight.c:5459 [i915]intel_backlight_device_register =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_opregion.c:43 [i915]intel_opregion_notify_encoder =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_opregion.c:53 [i915]asle_set_backlight =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_bios.c:1088 [i915]intel_bios_is_dsi_present =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/display/intel_display_debugfs.c:6153 [i915]i915_drrs_ctl_set =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/intel_pcode.c:26 [i915]snb_pcode_read =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/i915/i915_getparam.c:785 [i915]i915_getparam_ioctl =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c:282 [amdgpu]vcn_v2_5_process_interrupt =_ "todo: maybe avoid via dyndbg\n" drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:433 [amdgpu]vcn_v2_0_process_interrupt =_ "todo: maybe avoid via dyndbg\n" :#> Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220912052852.1123868-8-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index 29a2994..cb203d6 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -285,7 +285,7 @@ void __drm_dev_dbg(const struct device *dev, enum drm_debug_category category, struct va_format vaf; va_list args; - if (!drm_debug_enabled(category)) + if (!__drm_debug_enabled(category)) return; va_start(args, format); @@ -308,7 +308,7 @@ void ___drm_dbg(enum drm_debug_category category, const char *format, ...) struct va_format vaf; va_list args; - if (!drm_debug_enabled(category)) + if (!__drm_debug_enabled(category)) return; va_start(args, format); diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index dfdd81c..9af57d3 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -321,11 +321,30 @@ enum drm_debug_category { DRM_UT_DRMRES }; -static inline bool drm_debug_enabled(enum drm_debug_category category) +static inline bool drm_debug_enabled_raw(enum drm_debug_category category) { return unlikely(__drm_debug & BIT(category)); } +#define drm_debug_enabled_instrumented(category) \ + ({ \ + pr_debug("todo: is this frequent enough to optimize ?\n"); \ + drm_debug_enabled_raw(category); \ + }) + +#if defined(CONFIG_DRM_USE_DYNAMIC_DEBUG) +/* + * the drm.debug API uses dyndbg, so each drm_*dbg macro/callsite gets + * a descriptor, and only enabled callsites are reachable. They use + * the private macro to avoid re-testing the enable-bit. + */ +#define __drm_debug_enabled(category) true +#define drm_debug_enabled(category) drm_debug_enabled_instrumented(category) +#else +#define __drm_debug_enabled(category) drm_debug_enabled_raw(category) +#define drm_debug_enabled(category) drm_debug_enabled_raw(category) +#endif + /* * struct device based logging *